1
|
Takahashi Y, Kobayashi M, Kawase Y. Photocatalytic degradation process of antibiotic sulfamethoxazole by ZnO in aquatic systems: a dynamic kinetic model based on contributions of OH radical, oxygenated radical intermediates and dissolved oxygen. J Environ Sci Health A Tox Hazard Subst Environ Eng 2024; 59:113-124. [PMID: 38619314 DOI: 10.1080/10934529.2024.2339171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 03/27/2024] [Indexed: 04/16/2024]
Abstract
The photocatalytic degradation process of sulfamethoxazole (SMX) using ZnO in aquatic systems has been systematically studied by varying initial SMX concentration from 0 to 15 mgL-1, ZnO dosage from 0 to 4 gL-1 and UV light intensity at the light source from 0 to 18 W(m-lamp length)-1 at natural pH. Almost complete degradations of SMX were achieved within 120 min for the initial SMX concentration ≤15 mgL-1 with ZnO dosage of 3 gL-1 and UV light intensity of 18 W(m-lamp length)-1. The photocatalytic degradation process was found to be interacted with the dissolved oxygen (DO) consumption. With oxygen supply through the gas-liquid free-surface, the DO concentration decreased significantly in the initial SMX degradation phase and increased asymptotically to the saturated DO concentration after achieving about 80% SMX degradation. The change in DO concentration was probably controlled by the oxygen consumption in the formation of oxygenated radical intermediates. A novel dynamic kinetic model based on the fundamental reactions of photocatalysis and the formation of oxygenated radical intermediates was developed. In the modeling the dynamic concentration profiles of OH radical and DO are considered. The dynamics of SMX degradation process by ZnO was simulated reasonably by the proposed model.
Collapse
Affiliation(s)
- Yuka Takahashi
- Research Center for Biochemical and Environmental Engineering, Department of Applied Chemistry, Toyo University, Kawagoe, Saitama, Japan
| | - Maki Kobayashi
- Research Center for Biochemical and Environmental Engineering, Department of Applied Chemistry, Toyo University, Kawagoe, Saitama, Japan
| | - Yoshinori Kawase
- Research Center for Biochemical and Environmental Engineering, Department of Applied Chemistry, Toyo University, Kawagoe, Saitama, Japan
| |
Collapse
|
2
|
Samia B, Della Puppa L, Mattei C, Durand A, Ravier S, Quivet E, Wortham H. Influence of pesticide mixture on their heterogeneous atmospheric degradation by ozone and OH radicals. Environ Pollut 2024; 344:123351. [PMID: 38272169 DOI: 10.1016/j.envpol.2024.123351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 01/27/2024]
Abstract
Pesticides in the atmosphere can exist in both gaseous and particulate phases due to their semi-volatile properties. They can undergo degradation when exposed to atmospheric oxidants like ozone and hydroxyl radicals. The majority of studies on the atmospheric reactivity of pesticides study them in combination, without considering potential mixture effects that could induce uncertainties in the results. Therefore, this study aims to address this gap, through laboratory studies using a flow reactor, and by evaluating the degradation kinetics of pendimethalin mixed with folpet, tebuconazole, and S-metolachlor, which were simultaneously adsorbed on hydrophobic silica particles that mimic atmospheric aerosols. The comparison with other mixtures, including pendimethalin, from the literature has shown similar reactivity with ozone and hydroxyl radicals, indicating that the degradation kinetics of pesticides is independent of the mixture. Moreover, the degradation rates of the four pesticides under study indicate that they are not or slightly degraded by ozone, with half-lives ranging from 29 days to over 800 days. In contrast, when exposed to hydroxyl radicals, tebuconazole exhibited the fastest reactivity, with a half-life of 4 days, while pendimethalin had a half-life of 17 days.
Collapse
Affiliation(s)
- Boulos Samia
- Aix Marseille Univ, CNRS, LCE, Marseille, France
| | | | - Coraline Mattei
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
| | | | | | | | | |
Collapse
|
3
|
Wang X, Wang W, Wingen LM, Perraud V, Finlayson-Pitts BJ. Top-down versus bottom-up oxidation of a neonicotinoid pesticide by OH radicals. Proc Natl Acad Sci U S A 2024; 121:e2312930121. [PMID: 38315860 PMCID: PMC10873643 DOI: 10.1073/pnas.2312930121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 11/17/2023] [Indexed: 02/07/2024] Open
Abstract
Emerging contaminants (EC) distributed on surfaces in the environment can be oxidized by gas phase species (top-down) or by oxidants generated by the underlying substrate (bottom-up). One class of EC is the neonicotinoid (NN) pesticides that are widely distributed in air, water, and on plant and soil surfaces as well as on airborne dust and building materials. This study investigates the OH oxidation of the systemic NN pesticide acetamiprid (ACM) at room temperature. ACM on particles and as thin films on solid substrates were oxidized by OH radicals either from the gas phase or from an underlying TiO2 or NaNO2 substrate, and for comparison, in the aqueous phase. The site of OH attack is both the secondary >CH2 group as well as the primary -CH3 group attached to the tertiary amine nitrogen, with the latter dominating. In the case of top-down oxidation of ACM by gas phase OH radicals, addition to the -CN group also occurs. Major products are carbonyls and alcohols, but in the presence of sufficient water, their hydrolyzed products dominate. Kinetics measurements show ACM is more reactive toward gas phase OH radicals than other NN nitroguanidines, with an atmospheric lifetime of a few days. Bottom-up oxidation of ACM on TiO2 exposed to sunlight outdoors (temperatures were above 30 °C) was also shown to occur and is likely to be competitive with top-down oxidation. These findings highlight the different potential oxidation processes for EC and provide key data for assessing their environmental fates and toxicologies.
Collapse
Affiliation(s)
- Xinke Wang
- Department of Chemistry, University of California, Irvine, CA92697-2025
| | - Weihong Wang
- Department of Chemistry, University of California, Irvine, CA92697-2025
| | - Lisa M. Wingen
- Department of Chemistry, University of California, Irvine, CA92697-2025
| | - Véronique Perraud
- Department of Chemistry, University of California, Irvine, CA92697-2025
| | | |
Collapse
|
4
|
Li R, Gao Y, Han Y, Zhang Y, Zhang B, Fu H, Wang G. Elucidating the mechanisms of rapid O 3 increase in North China Plain during COVID-19 lockdown period. Sci Total Environ 2024; 906:167622. [PMID: 37806584 DOI: 10.1016/j.scitotenv.2023.167622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 10/02/2023] [Accepted: 10/04/2023] [Indexed: 10/10/2023]
Abstract
Ozone (O3) levels in North China Plain (NCP) suffered from rapid increases during the COVID-19 period. Many previous studies have confirmed more rapid NOx reduction compared with VOCs might be responsible for the O3 increase during this period, while the comprehensive impacts of each VOC species and NOx on ambient O3 and their interactions with meteorology were not revealed clearly. To clarify the detailed reasons for the O3 increase, a continuous campaign was performed in a typical industrial city of NCP. Meanwhile, the machine-learning technique and the box model were employed to reveal the mechanisms of O3 increase from the perspective of meteorology and photochemical process, respectively. The result suggested that the ambient O3 level in Tangshan increased from 18.7 ± 4.63 to 45.6 ± 8.52 μg/m3 (143%) during COVID-19 lockdown, and the emission reduction and meteorology contributed to 54 % and 46 % of this increment, respectively. The lower wind speed (WS) coupled with regional transport played a significant role on O3 increase (30.8 kg/s). The O3 sensitivity verified that O3 production was highly volatile organic compounds (VOC)-sensitive (Relative incremental reactivity (RIR): 0.75), while the NOx showed the negative impact on O3 production in Tangshan (RIR: -0.59). It suggested that the control of VOCs rather than NOx might be more effective in reducing O3 level in Tangshan because it was located on the VOC-limited regime. Besides, both of ozone formation potential (OFP) analysis and observation-based model (OBM) demonstrated that the alkenes (36.3 ppb) and anthropogenic oxygenated volatile organic compounds (OVOCs) (15.2 ppb) showed the higher OFP compared with other species, and their reactions released a large number of HO2 and RO2 radicals. Moreover, the concentrations of these species did not experience marked decreases during COVID-19 lockdown, which were major contributors to O3 increase during this period. This study also underlined the necessity of priority controlling alkenes and OVOCs across the NCP.
Collapse
Affiliation(s)
- Rui Li
- Key Laboratory of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai 200241, PR China.
| | - Yining Gao
- Key Laboratory of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai 200241, PR China
| | - Yu Han
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, PR China
| | - Yi Zhang
- Tangshan Ecological Environment Publicity and Education Center, Tangshan 063000, Hebei, PR China
| | - Baojun Zhang
- Tangshan Ecological Environment Publicity and Education Center, Tangshan 063000, Hebei, PR China
| | - Hongbo Fu
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, PR China
| | - Gehui Wang
- Key Laboratory of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai 200241, PR China.
| |
Collapse
|
5
|
Tomei G, Saleem M, Ceriani E, Pinton A, Marotta E, Paradisi C. Cold Plasma for Green Advanced Reduction/Oxidation Processes (AROPs) of Organic Pollutants in Water. Chemistry 2023; 29:e202302090. [PMID: 37621157 DOI: 10.1002/chem.202302090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/21/2023] [Accepted: 08/21/2023] [Indexed: 08/26/2023]
Abstract
Cold plasma is gaining increasing attention as a novel tool to activate energy demanding chemical processes, including advanced reduction/oxidation processes (AROPs) of organic pollutants in water. The very complex milieu generated by discharges at the water/plasma interface comprises photons, strong oxidants and strong reductants which can be exploited for achieving the degradation of most any kind of pollutants. Despite the complexity of these systems, the powerful arsenal of mechanistic tools and chemical probes of physical organic chemists can be usefully applied to understand and develop plasma chemistry. Specifically, the added value of air plasma generated by in situ discharge with respect to ozonation (ex situ discharge) is demonstrated using phenol and various phenol derivatives and mechanistic evidence for the prevailing role of hydroxyl radicals in the initial attack is presented. On the reduction front, the impressive performance of cold plasma in inducing the degradation of recalcitrant perfluoroalkyl substances, which do not react with OH radicals but are attacked by electrons, is reported and discussed. The widely different reactivities of perfluorooctanoic acid (PFOA) and of perfluorobutanoic acid (PFBA) underline the crucial role played in these processes by the interface between plasma and solution and the surfactant properties of the treated pollutants.
Collapse
Affiliation(s)
- Giulia Tomei
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Mubbshir Saleem
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Elisa Ceriani
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Anna Pinton
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Ester Marotta
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Cristina Paradisi
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| |
Collapse
|
6
|
Ghimire A, Hasan F, Guan X, Potter P, Guo C, Lomnicki S. Oxidation 1-methyl naphthalene based on the synergy of environmentally persistent free radicals (EPFRs) and PAHs in particulate matter (PM) surface. Chemosphere 2023; 341:140002. [PMID: 37648160 PMCID: PMC10548478 DOI: 10.1016/j.chemosphere.2023.140002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 05/15/2023] [Accepted: 08/26/2023] [Indexed: 09/01/2023]
Abstract
Studies of the environmental fate through the interactions of particle-associated polycyclic aromatic hydrocarbons (PAHs) with environmentally persistent free radicals (EPFRs) are presented. The formation of PAHs and EPFRs typically occurs side by side during combustion-processes. The laboratory simulation studies of the model PAH molecule 1-Methylnaphthalene (1-MN) interaction with model EPFRs indicate a transformational synergy between these two pollutants due to mutual and matrix interactions. EPFRs, thorough its redox cycle result in the oxidation of PAHs into oxy-/hydroxy-PAHs. EPFRs have been shown before to produce OH radical during its redox cycle in aqueous media and this study has shown that produced OH radical can transform other PM constituents resulting in alteration of PM chemistry. In model PM, EPFRs driven oxidation process of 1-MN produced 1,4-naphthoquinone, 1-naphthaldehyde, 4-hydroxy-4-methylnaphthalen-1-one, and various isomers of (hydroxymethyl) naphthalene. Differences were observed in oxidation product yields, depending on whether EPFRs and PAHs were cohabiting the same PM or present on separate PM. This effect is attributed to the OH radical concentration gradient as a factor in the oxidation process, further strengthening the hypothesis of EPFRs' role in the PAH oxidation process. This finding is revealing new environmental role of EPFRs in a natural degradation process of PAHs. Additionally, it points to implications of such PM surface chemistry in the changing mobility of PAHs into an aqueous medium, thus increasing their bioavailability.
Collapse
Affiliation(s)
- Ajit Ghimire
- Department of Environmental Sciences, Louisiana State University, Baton Rouge, LA, 70803, United States
| | - Farhana Hasan
- Department of Environmental Sciences, Louisiana State University, Baton Rouge, LA, 70803, United States
| | - Xia Guan
- Department of Environmental Sciences, Louisiana State University, Baton Rouge, LA, 70803, United States
| | - Phillip Potter
- Department of Environmental Sciences, Louisiana State University, Baton Rouge, LA, 70803, United States
| | - Chuqi Guo
- Department of Environmental Sciences, Louisiana State University, Baton Rouge, LA, 70803, United States
| | - Slawo Lomnicki
- Department of Environmental Sciences, Louisiana State University, Baton Rouge, LA, 70803, United States.
| |
Collapse
|
7
|
Gao L, Wu H, Dang J, Zhang S, Tian S, Zhang Q, Wang W. New insight into the removal process of benzotriazole UV stabilizers by UV/H 2O 2: Integrating quantum chemical calculation with CFD simulation. J Hazard Mater 2023; 459:132245. [PMID: 37562354 DOI: 10.1016/j.jhazmat.2023.132245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 07/25/2023] [Accepted: 08/05/2023] [Indexed: 08/12/2023]
Abstract
Benzotriazole UV stabilizers (BT-UVs) are important UV absorbers. As high-production chemicals and potential hazards, their ubiquitous presence in aquatic environments is of greatly pressing concern. Herein, the removal of six typical BT-UVs by UV/H2O2 was comprehensively investigated by quantum chemistry calculation integrated with CFD simulation. Utilizing such a micro and macro incorporated model in treating contaminants is the first report. From the micro-view, degradation mechanisms of BT-UVs by •OH oxidation were determined, and corresponding rate constants were obtained with values of 109∼1010 M-1s-1. In a macroscopic aspect, combining the established kinetic model and CFD simulation, the effects of UV lamp power (P), volumetric flow rate (Qv), and H2O2 dosage ([H2O2]0) on removal yields of BT-UVs were expounded, increasing P or [H2O2]0 or decreasing Qv are effective in improving removal yields of BT-UVs, but the enhancement was abated when P or [H2O2]0 increased to a certain level. When [H2O2]0 is 5 mg/L and Qv is decreased from 0.1 to 0.05 m3/h, the removal yields of BT-UVs could achieve more than 95% (P = 150 W) and 99% (P = 250 W), respectively. This work provides a new interdisciplinary insight for investigating organic contaminant removal in potential industrial applications of UV/H2O2 systems.
Collapse
Affiliation(s)
- Li'ao Gao
- Environment Research Institute, Shandong University, Qingdao 266237, China
| | - Hongjin Wu
- Environment Research Institute, Shandong University, Qingdao 266237, China
| | - Juan Dang
- Environment Research Institute, Shandong University, Qingdao 266237, China.
| | - Shibo Zhang
- Environment Research Institute, Shandong University, Qingdao 266237, China.
| | - Shuai Tian
- Department of Cardiology, The Eighth Affiliated Hospital, Sun Yat-sen University, Shenzhen, Guangdong 518033, China; Guangdong Innovative Engineering and Technology Research Center for Assisted Circulation, Sun Yat-sen University, Shenzhen 518033, China; Department of Chemical Engineering, University of Bath, Bath BA2 7AY, UK.
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Qingdao 266237, China
| | - Wenxing Wang
- Environment Research Institute, Shandong University, Qingdao 266237, China
| |
Collapse
|
8
|
Xu Y, Shen W. Flocculation synergistic with nano zero-valent iron augmented attapulgite @ chitosan as Fenton-like catalyst for the treatment of landfill leachate. Environ Technol 2023; 44:3605-3613. [PMID: 35440289 DOI: 10.1080/09593330.2022.2068377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 04/02/2022] [Indexed: 06/14/2023]
Abstract
In this study, nano-zero-valent iron (NZVI) was added to attapulgite/chitosan and used as a catalyst in the heterogeneous Fenton process to degrade stabilized landfill leachate. Landfill leachate has serious environmental impacts due to the complexity and diversity of its pollutants. A magnetic catalyst (NZVI@PATP/CS) was prepared by a liquid-phase reduction method. The NZVI@PATP/CS were characterized by XRD, FTIR and SEM. The pH of leachate and the dosage of catalyst and H2O2 were changed to determine the best-operating conditions for the effective removal of chemical oxygen demand (COD) and total phosphorus(TP). To understand the adsorption degradation mechanism, the quenching experiments of free radicals were carried out. The results showed that the degradation rates of COD and TP were 66% and 92%, respectively, under the optimum pH value of 8, the dosage of H2O2 of 5 mL, and the dosage of the catalyst of 0.25 g for 60 min.
Collapse
Affiliation(s)
- Yongyao Xu
- School of Materials Science and Engineering, Anhui University of Science and Technology, Huainan, Anhui, People's Republic of China
- College of Chemistry and Chemical Engineering, Neijiang Normal University, Neijiang, Sichuan, People's Republic of China
| | - Wangqing Shen
- College of Chemistry and Chemical Engineering, Neijiang Normal University, Neijiang, Sichuan, People's Republic of China
| |
Collapse
|
9
|
Kazmierczak L, Szala-Rearick J, Swiatla-Wojcik D. 3D Characterization of the Molecular Neighborhood of (•) OH Radical in High Temperature Water by MD Simulation and Voronoi Polyhedra. Int J Mol Sci 2023; 24. [PMID: 36834704 DOI: 10.3390/ijms24043294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 01/27/2023] [Accepted: 02/03/2023] [Indexed: 02/10/2023] Open
Abstract
Understanding the properties of the •OH radical in aqueous environments is essential for biochemistry, atmospheric chemistry, and the development of green chemistry technologies. In particular, the technological applications involve knowledge of microsolvation of the •OH radical in high temperature water. In this study, the classical molecular dynamics (MD) simulation and the technique based on the construction of Voronoi polyhedra were used to provide 3D characteristics of the molecular vicinity of the aqueous hydroxyl radical (•OHaq). The statistical distribution functions of metric and topological features of solvation shells represented by the constructed Voronoi polyhedra are reported for several thermodynamic states of water, including the pressurized high-temperature liquid and supercritical fluid. Calculations showed a decisive influence of the water density on the geometrical properties of the •OH solvation shell in the sub- and supercritical region: with the decreasing density, the span and asymmetry of the solvation shell increase. We also showed that the 1D analysis based on the oxygen-oxygen radial distribution functions (RDFs) overestimates the solvation number of •OH and insufficiently reflects the influence of transformations in the hydrogen-bonded network of water on the structure of the solvation shell.
Collapse
|
10
|
Park J, Lam SS, Park YK, Kim BJ, An KH, Jung SC. Fabrication of Ni/TiO 2 visible light responsive photocatalyst for decomposition of oxytetracycline. Environ Res 2023; 216:114657. [PMID: 36328223 DOI: 10.1016/j.envres.2022.114657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 09/19/2022] [Accepted: 10/22/2022] [Indexed: 06/16/2023]
Abstract
Nickel-impregnated TiO2 photocatalyst (NiTP) responding to visible light was prepared by the liquid phase plasma (LPP) method, and its photoactivity was evaluated in degrading an antibiotic (oxytetracycline, OTC). For preparing the photocatalyst, nickel was uniformly impregnated onto TiO2 (P-25) powder, and the nickel content increased as the number of LPP reactions increased. In addition, the morphology and lattice of NiTP were observed through various instrumental analyses, and it was confirmed that NiO-type nanoparticles were impregnated in NiTP. Fundamentally, as the amount of impregnated nickel in the TiO2 powder increased sufficiently, the band gap energy of TiO2 decreased, and eventually, the NiTP excited by visible light was synthesized. Further, OTC had a decomposition reaction pathway in which active radicals generated in OTC photocatalytic reaction under NiTP were finally mineralized through reactions such as decarboxamidation, hydration, deamination, demethylation, and dehydroxylation. In effect, we succeeded in synthesizing a photocatalyst useable under visible light by performing only the LPP single process and developed a new advanced oxidation process (AOP) that can remove toxic antibiotics.
Collapse
Affiliation(s)
- Jaegu Park
- Dept. of Environ. Eng., Sunchon Nat'l Univ., 255 Sunchon 57922, South Korea
| | - Su Shiung Lam
- Higher Institute Center of Excellences, Univ. Malaysia Terengganu, Kuala Neruss 21030, Malaysia
| | - Young-Kwon Park
- School of Environ. Eng., Univ. of Seoul, Seoul 02504, South Korea
| | - Byung-Joo Kim
- Dept. of Nano & Advanced Mater. Eng., Jeonju Univ., 303 Jeonju 55069, South Korea
| | - Kay-Hyeok An
- Dept. of Nano & Advanced Mater. Eng., Jeonju Univ., 303 Jeonju 55069, South Korea
| | - Sang-Chul Jung
- Dept. of Environ. Eng., Sunchon Nat'l Univ., 255 Sunchon 57922, South Korea.
| |
Collapse
|
11
|
Deng H, Xu X, Wang K, Xu J, Loisel G, Wang Y, Pang H, Li P, Mai Z, Yan S, Li X, Gligorovski S. The Effect of Human Occupancy on Indoor Air Quality through Real-Time Measurements of Key Pollutants. Environ Sci Technol 2022; 56:15377-15388. [PMID: 36279129 DOI: 10.1021/acs.est.2c04609] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The primarily emitted compounds by human presence, e.g., skin and volatile organic compounds (VOCs) in breath, can react with typical indoor air oxidants, ozone (O3), and hydroxyl radicals (OH), leading to secondary organic compounds. Nevertheless, our understanding about the formation processes of the compounds through reactions of indoor air oxidants with primary emitted pollutants is still incomplete. In this study we performed real-time measurements of nitrous acid (HONO), nitrogen oxides (NOx = NO + NO2), O3, and VOCs to investigate the contribution of human presence and human activity, e.g., mopping the floor, to secondary organic compounds. During human occupancy a significant increase was observed of 1-butene, isoprene, and d-limonene exhaled by the four adults in the room and an increase of methyl vinyl ketone/methacrolein, methylglyoxal, and 3-methylfuran, formed as secondary compounds through reactions of OH radicals with isoprene. Intriguingly, the level of some compounds (e.g., m/z 126, 6-methyl-5-hepten-2-one, m/z 152, dihydrocarvone, and m/z 194, geranyl acetone) formed through reactions of O3 with the primary compounds was higher in the presence of four adults than during the period of mopping the floor with commercial detergent. These results indicate that human presence can additionally degrade the indoor air quality.
Collapse
Affiliation(s)
- Huifan Deng
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou510640, China
- University of Chinese Academy of Sciences, Beijing100864, China
| | - Xin Xu
- Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou510632, China
| | - Kangyi Wang
- Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou510632, China
| | - Jinli Xu
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou510640, China
- University of Chinese Academy of Sciences, Beijing100864, China
| | - Gwendal Loisel
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou510640, China
| | - Yiqun Wang
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou510640, China
- University of Chinese Academy of Sciences, Beijing100864, China
| | - Hongwei Pang
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou510640, China
| | - Pan Li
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou510640, China
- University of Chinese Academy of Sciences, Beijing100864, China
| | - Zebin Mai
- Guangzhou Hexin Instrument Co., Ltd., Guangzhou510530, China
| | - Shichao Yan
- Guangzhou Hexin Instrument Co., Ltd., Guangzhou510530, China
| | - Xue Li
- Institute of Mass Spectrometry and Atmospheric Environment, Jinan University, Guangzhou510632, China
- Guangdong Provincial Engineering Research Center for On-line Source Apportionment System of Air Pollution, Guangzhou510632, China
- Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou510632, China
| | - Sasho Gligorovski
- State Key Laboratory of Organic Geochemistry and Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou510640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou510640, China
- Chinese Academy of Science, Center for Excellence in Deep Earth Science, Guangzhou510640, China
| |
Collapse
|
12
|
Hu M, Tonokura K, Morino Y, Sato K, Enami S. Effects of Metal Ions on Aqueous-Phase Decomposition of α-Hydroxyalkyl-Hydroperoxides Derived from Terpene Alcohols. Environ Sci Technol 2021; 55:12893-12901. [PMID: 34525797 DOI: 10.1021/acs.est.1c04635] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We report the results of a mass spectrometric study of the effects of atmospherically relevant metal ions on the decomposition of α-hydroxyalkyl-hydroperoxides (α-HHs) derived from ozonolysis of α-terpineol in aqueous solutions. By direct mass spectrometric detection of chloride adducts of α-HHs, we assessed the temporal profiles of α-HHs and other products in the presence of metal ions. In addition, reactions between α-HHs and FeCl2 in the presence of excess DMSO showed that the amount of hydroxyl radicals formed in a mixture of α-terpineol, O3, and FeCl2 was 5.7 ± 0.8% of the amount formed in a mixture of H2O2 and FeCl2. The first-order rate constants for the decay of α-HHs produced by ozonolysis of α-terpineol in the presence of 5 mM acetate buffer at a pH of 5.1 ± 0.1 were determined to be (4.5 ± 0.1) × 10-4 s-1 (no metal ions), (4.7 ± 0.2) × 10-4 s-1 (with 0.05 mM Fe2+), (4.7 ± 0.1) × 10-4 s-1 (with 0.05 mM Zn2+), and (4.8 ± 0.2) × 10-4 s-1 (with 0.05 mM Cu2+). We propose that in acidic aqueous media, the reaction of α-HHs with Fe2+ is outcompeted by H+-catalyzed decomposition of α-HHs, which produces the corresponding aldehydes and H2O2, which can in turn react with Fe2+ to form hydroxyl radicals.
Collapse
Affiliation(s)
- Mingxi Hu
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8563, Japan
| | - Kenichi Tonokura
- Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8563, Japan
| | - Yu Morino
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506, Japan
| | - Kei Sato
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506, Japan
| | - Shinichi Enami
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506, Japan
| |
Collapse
|
13
|
Abstract
Numerical simulations for sonochemistry are reviewed including single-bubble sonochemistry, influence of ultrasonic frequency and bubble size, acoustic field, and sonochemical synthesis of nanoparticles. The theoretical model of bubble dynamics including the effect of non-equilibrium chemical reactions inside a bubble has been validated from the study of single-bubble sonochemistry. By the numerical simulations, it has been clarified that there is an optimum bubble temperature for the production of oxidants inside an air bubble such as OH radicals and H2O2 because at higher temperature oxidants are strongly consumed inside a bubble by oxidizing nitrogen. Unsolved problems are also discussed.
Collapse
Affiliation(s)
- Kyuichi Yasui
- National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan.
| |
Collapse
|
14
|
Kawaguchi K, Wang Y, Xu J, Ootani Y, Higuchi Y, Ozawa N, Kubo M. Atom-by-Atom and Sheet-by-Sheet Chemical Mechanical Polishing of Diamond Assisted by OH Radicals: A Tight-Binding Quantum Chemical Molecular Dynamics Simulation Study. ACS Appl Mater Interfaces 2021; 13:41231-41237. [PMID: 34403585 DOI: 10.1021/acsami.1c09468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Ultraflat and damage-free single-crystal diamond is a promising material for use in electronic devices such as field-effect transistors. Diamond surfaces are conventionally prepared by the chemical mechanical polishing (CMP) method, although the CMP efficiency remains a critical issue owing to the extremely high hardness of diamond. Recently, OH radicals have been demonstrated to be potentially useful for improving the CMP efficiency for diamond; however, the underlying mechanisms are still elusive. In this work, we applied our previously developed CMP-specialized tight-binding quantum chemical molecular dynamics simulator to comprehensively elucidate the CMP mechanisms of diamond assisted by OH radicals. Our simulation results indicate that the diamond surface is oxidized by reactions with OH radicals and then a concomitant surface reconstruction takes place due to the distorted and unstable nature of the oxidized diamond surface structure. Furthermore, we interestingly reveal that the reconstruction of the diamond surface ultimately leads to two distinct removal mechanisms: (i) gradual atom-by-atom removal through the desorption of gaseous molecules (e.g., CO2 and H2CO3) and (ii) drastic sheet-by-sheet removal through the exfoliation of graphitic ring structures. Hence, we propose that promoting the oxidation-induced graphitization of the diamond surface may provide a route to further improving the CMP efficiency.
Collapse
Affiliation(s)
- Kentaro Kawaguchi
- Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Yang Wang
- Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Department of Mechanical Systems Engineering, Graduate School of Engineering, Tohoku University, 6-6-01 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan
| | - Jingxiang Xu
- Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- College of Engineering Science and Technology, Shanghai Ocean University, 999 Hucheng Ring Road, Pudong, Shanghai 201306, China
| | - Yusuke Ootani
- Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Yuji Higuchi
- Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Nobuki Ozawa
- Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan
| | - Momoji Kubo
- Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan
| |
Collapse
|
15
|
Hynniewta S, Lily M, Chandra AK. Computational investigations on kinetics of reaction between t-butanol and OH radical and ozone formation potential. J Mol Graph Model 2021; 108:108002. [PMID: 34391199 DOI: 10.1016/j.jmgm.2021.108002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 07/30/2021] [Accepted: 08/04/2021] [Indexed: 10/20/2022]
Abstract
The kinetics of the gas-phase atmospheric reaction of t-butanol with OH radicals is computationally studied using the CCSD(T)/aug-cc-pVTZ//M06-2X/6-311++G(d,p) level of calculation. The rate coefficients are evaluated for a wide temperature range of 250-1200 K and the calculated rate coefficient value of 0.83×10-12cm3molecule-1s-1 at 298K is in close agreement with experimental results. The H-abstraction from the -CH3 group is predicted to be the main reaction channel. A weak negative temperature dependence of rate coefficient is observed in 250-300 K. The study also highlighted the possibility of re-generation of OH radicals at higher temperature. The ozone formation potential of t-butanol in the troposphere has also been estimated and discussed.
Collapse
Affiliation(s)
- Shemphang Hynniewta
- Department of Chemistry, North-Eastern Hill University, Shillong, 793 022, India
| | - Makroni Lily
- Key Laboratory of Applied Surface and Colloid Chemistry of Ministry of Education, Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi'an, Shaanxi, 710119, China
| | - Asit K Chandra
- Department of Chemistry, North-Eastern Hill University, Shillong, 793 022, India.
| |
Collapse
|
16
|
Jiang H, Li J, Sun R, Tian C, Tang J, Jiang B, Liao Y, Chen CE, Zhang G. Molecular Dynamics and Light Absorption Properties of Atmospheric Dissolved Organic Matter. Environ Sci Technol 2021; 55:10268-10279. [PMID: 34286571 DOI: 10.1021/acs.est.1c01770] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The light-absorbing organic aerosol referred to as brown carbon (BrC) affects the global radiative balance. The linkages between its molecular composition and light absorption properties and how environmental factors influence BrC composition are not well understood. In this study, atmospheric dissolved organic matter (ADOM) in 55 aerosol samples from Guangzhou was characterized using Fourier transform ion cyclotron resonance mass spectrometry and light absorption measurements. The abundant components in ADOM were aliphatics and peptide-likes (in structure), or nitrogen- and sulfur-containing compounds (in elemental composition). The light absorption properties of ADOM were positively correlated with the levels of unsaturated and aromatic structures. Particularly, 17 nitrogen-containing species, which are identified by a random forest, characterized the variation of BrC absorption well. Aggregated boosted tree model and nonmetric multidimensional scaling analysis show that the BrC composition was largely driven by meteorological conditions and anthropogenic activities, among which biomass burning (BB) and OH radical were the two important factors. BrC compounds often accumulate with elevated BB emissions and related secondary processes, whereas the photolysis/photooxidation of BrC usually occurs under high solar radiance/•OH concentration. This study first illuminated how environmental factors influence BrC at the molecular level and provided clues for the molecular-level research of BrC in the future.
Collapse
Affiliation(s)
- Hongxing Jiang
- State Key Laboratory of Organic Geochemistry and Guangdong Province Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jun Li
- State Key Laboratory of Organic Geochemistry and Guangdong Province Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China
| | - Rong Sun
- State Key Laboratory of Organic Geochemistry and Guangdong Province Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chongguo Tian
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
| | - Jiao Tang
- State Key Laboratory of Organic Geochemistry and Guangdong Province Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China
| | - Bin Jiang
- State Key Laboratory of Organic Geochemistry and Guangdong Province Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China
| | - Yuhong Liao
- State Key Laboratory of Organic Geochemistry and Guangdong Province Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China
| | - Chang-Er Chen
- Environmental Research Institute/School of Environment, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China
| | - Gan Zhang
- State Key Laboratory of Organic Geochemistry and Guangdong Province Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou 510640, China
- Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou 510640, China
| |
Collapse
|
17
|
Park YK, Kim BJ, Kim SC, You CS, Choi J, Park J, Lee H, Jung SC. Decomposition of naproxen by plasma in liquid process with TiO 2 photocatslysts and hydrogen peroxide. Environ Res 2021; 195:110899. [PMID: 33610581 DOI: 10.1016/j.envres.2021.110899] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 02/08/2021] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
Naproxen (NPX), one of the representative non-steroidal anti-inflammatory drug (NSAID) ingredients, was decomposed by plasma in liquid process (PiLP). Strongly oxidized species generated in the plasma field of the PiLP, such as OH radicals, were confirmed by optical emission spectroscopy Increasing the operation parameters (pulse width, frequency and applied voltage) of the power supply promoted plasma field generation and OH radical generation, and affected the NPX decomposition rate. Although the NPX decomposition reaction rate was improved by up to 18-30% by adding TiO2 photocatalyst powder and H2O2 to PiLP, but the optimal addition amount should be determined considering the plasma generation and scavenger effects. A decomposition pathway was proposed, in which NPX was mineralized into CO2 and H2O through five intermediates mainly by decarboxylation, demethylation, hydroxylation, and dehydration reactions via hydroxyl radicals.
Collapse
Affiliation(s)
- Young-Kwon Park
- University of Seoul, School of Environmental Engineering, 163 Seoulsiripdaero, Dongdaemun-gu, Seoul, 02504, South Korea
| | - Byung-Joo Kim
- Korea Institute of Carbon Convergence Technology, R&D Division, 110-11 Banryong-ro, Jeonju, 54853, South Korea
| | - Sang-Chai Kim
- Department of Environmental Education, Mokpo National University, 1666 Cheonggye-myeon, Muan-gun, 58554, South Korea
| | - Chan-Seo You
- Department of Environmental Engineering, Sunchon National University, 255 Jungang-ro, Sunchon, Jeonnam, 57922, South Korea
| | - Jaewook Choi
- Department of Environmental Engineering, Sunchon National University, 255 Jungang-ro, Sunchon, Jeonnam, 57922, South Korea
| | - Jaegu Park
- Department of Environmental Engineering, Sunchon National University, 255 Jungang-ro, Sunchon, Jeonnam, 57922, South Korea
| | - Heon Lee
- Department of Environmental Engineering, Sunchon National University, 255 Jungang-ro, Sunchon, Jeonnam, 57922, South Korea
| | - Sang-Chul Jung
- Department of Environmental Engineering, Sunchon National University, 255 Jungang-ro, Sunchon, Jeonnam, 57922, South Korea.
| |
Collapse
|
18
|
Sommariva R, Crilley LR, Ball SM, Cordell RL, Hollis LDJ, Bloss WJ, Monks PS. Enhanced wintertime oxidation of VOCs via sustained radical sources in the urban atmosphere. Environ Pollut 2021; 274:116563. [PMID: 33561599 DOI: 10.1016/j.envpol.2021.116563] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 05/25/2023]
Abstract
Daytime atmospheric oxidation chemistry is conventionally considered to be driven primarily by the OH radical, formed via photolytic sources. In this paper we examine how, during winter when photolytic processes are slow, chlorine chemistry can have a significant impact on oxidative processes in the urban boundary layer. Photolysis of nitryl chloride (ClNO2) provides a significant source of chlorine atoms, which enhances the oxidation of volatile organic compounds (VOCs) and the production of atmospheric pollutants. We present a set of observations of ClNO2 and HONO made at urban locations in central England in December 2014 and February 2016. While direct emissions and in-situ chemical formation of HONO continue throughout the day, ClNO2 is only formed at night and is usually completely photolyzed by midday. Our data show that, during winter, ClNO2 often persists through the daylight hours at mixing ratios above 10-20 ppt (on average). In addition, relatively high mixing ratios of daytime HONO (>65 ppt) provide a strong source of OH radicals throughout the day. The combined effects of ClNO2 and HONO result in sustained sources of Cl and OH radicals from sunrise to sunset, which form additional ozone, PAN, oxygenated VOCs, and secondary organic aerosol. We show that radical sources such as ClNO2 and HONO can lead to a surprisingly photoactive urban atmosphere during winter and should therefore be included in atmospheric chemical models.
Collapse
Affiliation(s)
- Roberto Sommariva
- Department of Chemistry, University of Leicester, Leicester, UK; School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK.
| | - Leigh R Crilley
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
| | - Stephen M Ball
- Department of Chemistry, University of Leicester, Leicester, UK
| | | | | | - William J Bloss
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
| | - Paul S Monks
- Department of Chemistry, University of Leicester, Leicester, UK
| |
Collapse
|
19
|
Subramani M, Saravanan V, Theerthagiri J, Subramaniam V, Pazhanivel T, Ramasamy S, Manickam S. Kinetics and degradation of camphene with OH radicals and its subsequent fate under the atmospheric O 2 and NO radicals - A theoretical study. Chemosphere 2021; 267:129250. [PMID: 33338722 DOI: 10.1016/j.chemosphere.2020.129250] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 11/28/2020] [Accepted: 12/06/2020] [Indexed: 06/12/2023]
Abstract
Camphene (C10H16) is an abundant bicyclic monoterpene in the atmosphere which can be easily oxidized by the atmospheric OH radicals. In this study, the oxidation of camphene with OH radicals and its subsequent reactions are studied using quantum chemical method. Thermochemical parameters show that the addition of OH radicals to the terminal C10 atom of camphene is thermodynamically more stable than the addition of OH radicals to the internal C7 atom of camphene. The reaction force profile demonstrates that the formation of two hydroxyalkoxy radical intermediates (I1a and I2a) are mainly dominated by the structural rearrangement with 94.28% and 99.43% of the total energy, respectively. The overall reaction rate coefficient for camphene + OH radical is 2.1⨯10-12 cm3 molecule-1 sec-1 at 298 K and 1 atm which agree well with the experimental reaction rate coefficient (5.58⨯10-11 cm3 molecule-1 sec-1) for the reaction of camphene with OH radical. The branching ratio for the addition of OH radical to the C10 position of camphene is 68.32%, and the C7 position of camphene is 31.68% at 298 K. The calculated lifetime reveals that camphene degrades quickly in the atmosphere owing to its short lifetime of 5.3 h. The obtained mechanistic and kinetic results reveal that the addition of OH radical to the C10 position is more dominant than the C7 position, and it is more stable and spontaneous in the atmosphere.
Collapse
Affiliation(s)
| | - Vinnarasi Saravanan
- Department of Physics, Bharathiar University, Coimbatore, Tamil Nadu, 641046, India
| | - Jayaraman Theerthagiri
- Department of Chemistry and Research Institute of Natural Sciences, Gyeongsang National University, Jinju, 52828, South Korea
| | | | - Thangavelu Pazhanivel
- Smart Materials Interface Laboratory, Department of Physics, Periyar University, Salem, Tamilnadu, 636011, India
| | - Shankar Ramasamy
- Department of Physics, Bharathiar University, Coimbatore, Tamil Nadu, 641046, India.
| | - Sivakumar Manickam
- Petroleum and Chemical Engineering, Faculty of Engineering, Universiti Teknologi Brunei, Bandar Seri Begawan, BE1410, Brunei Darussalam
| |
Collapse
|
20
|
Jose J, Philip L. Comparative study of degradation of toluene and methyl isobutyl ketone (MIBK) in aqueous solution by pulsed corona discharge plasma. J Environ Sci (China) 2021; 101:382-396. [PMID: 33334533 DOI: 10.1016/j.jes.2020.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 09/08/2020] [Accepted: 09/08/2020] [Indexed: 06/12/2023]
Abstract
Effectiveness of pulsed power plasma for the degradation of two toxic volatile organic compounds (VOCs), toluene and methyl isobutyl ketone (MIBK), in aqueous solution was evaluated. The plasma degradation of MIBK has been studied for the first time. The influence of initial concentration of target compound, solution pH and scavengers on percentage degradation was evaluated. 100% removal of 200 mg/L of toluene and MIBK was achieved both in liquid and gaseous phases after 12 and 16 min of plasma treatment, respectively. The first order rate constant of toluene and MIBK degradation (for 200 mg/L each) was 0.421 and 0.319 min-1 respectively when they were treated individually, and these values decreased slightly during degradation of their mixture. MIBK degradation was slower than toluene and it might be due to semi volatile and hydrophilic nature of MIBK. The effect of initial concentration of toluene and MIBK showed different degradation patterns. Highest degradation of both the compounds was obtained in neutral pH and in absence of scavengers. •OH radical was the major reactive species involved in their degradation. Their degradation in real environmental matrices showed that removal reduced significantly in secondary effluent due to scavenging of reactive species by various ions and organic matter. The total number of degradation intermediates identified in case of toluene and MIBK was 11 and 14 respectively and formate was the one recalcitrant byproduct generated. The degradation pathway of toluene and MIBK involving reactions of reactive oxygen and nitrogen species and reductive species is proposed.
Collapse
Affiliation(s)
- Jerin Jose
- Department of Civil Engineering, Indian Institute of Technology Madras, Chennai 600036, India
| | - Ligy Philip
- Department of Civil Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
| |
Collapse
|
21
|
Khan MSI, Lee NR, Ahn J, Kim JY, Kim JH, Kwon KH, Kim YJ. Degradation of different pesticides in water by microplasma: the roles of individual radicals and degradation pathways. Environ Sci Pollut Res Int 2021; 28:8296-8309. [PMID: 33058076 DOI: 10.1007/s11356-020-11127-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 10/04/2020] [Indexed: 05/28/2023]
Abstract
Pesticides are emergent toxins often identified in aquatic environments. In the present study, microplasma was employed to reduce the pesticide content in water. The degradation efficacy, rate, and pathways of standard organophosphorus pesticides (namely, chlorpyrifos, chlorpyrifos oxone, and diazinone) and an organochlorine pesticide (namely, DDT solution) were evaluated using microplasma. High-performance liquid chromatography (HPLC) analysis was performed to elucidate the degradation efficiency of pesticides as a function of plasma-produced substances that originally contributed to the main reduction procedure. Microplasma produces several types of radicals or reactive substances, for instance dissolved ozone (O3), nitrogen oxides, hydroxyl radicals (OH radicals), and hydrogen peroxide (H2O2). The removal potential differs due to the existence or absence of varieties of plasma-produced substances. The functions of major plasma-produced species on pesticide removal were determined by a passive technique. Nitrogen oxides showed a key role in organophosphorus pesticide removal, whereas dissolved ozone and OH radicals played major roles in DDT degradation. HPLC data showed that plasma-induced pesticide removal showed first-order reaction kinetics. The pesticide removal pathways through microplasma were validated by investigating the achieved data from LC-MS and GC-MS.
Collapse
Affiliation(s)
- Muhammad Saiful Islam Khan
- Food Safety and Hygiene Research Division, Korea Food Research Institute, Wanju-gun, Jeollabuk-do, 55365, Republic of Korea
| | - Na Ri Lee
- Food Safety and Hygiene Research Division, Korea Food Research Institute, Wanju-gun, Jeollabuk-do, 55365, Republic of Korea
| | - Jaehwan Ahn
- Food Safety and Hygiene Research Division, Korea Food Research Institute, Wanju-gun, Jeollabuk-do, 55365, Republic of Korea
| | - Ji Young Kim
- Food Safety and Hygiene Research Division, Korea Food Research Institute, Wanju-gun, Jeollabuk-do, 55365, Republic of Korea
| | - Jong Hoon Kim
- Food Safety and Hygiene Research Division, Korea Food Research Institute, Wanju-gun, Jeollabuk-do, 55365, Republic of Korea
| | - Ki Hyun Kwon
- Food Safety and Hygiene Research Division, Korea Food Research Institute, Wanju-gun, Jeollabuk-do, 55365, Republic of Korea
| | - Yun-Ji Kim
- Food Safety and Hygiene Research Division, Korea Food Research Institute, Wanju-gun, Jeollabuk-do, 55365, Republic of Korea.
- Department of Food Biotechnology, University of Science and Technology, Daejeon, 305-350, Republic of Korea.
| |
Collapse
|
22
|
Ding Z, Yi Y, Wang W, Zhang Q. Atmospheric degradation of chrysene initiated by OH radical: A quantum chemical investigation. Chemosphere 2021; 263:128267. [PMID: 33297211 DOI: 10.1016/j.chemosphere.2020.128267] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/27/2020] [Accepted: 09/02/2020] [Indexed: 06/12/2023]
Abstract
Chrysene, a four-ring polycyclic aromatic hydrocarbon (PAH), is recalcitrant to biodegradation and persistent in the environment due to its low water solubility. Here, we investigated the atmospheric degradation process of chrysene initiated by OH radical in the presence of O2 and NOX using quantum chemical calculations. The reaction mechanisms were elucidated by density functional theory (DFT) at M06-2X/6-311++G(3df,2p)//M06-2X/6-311+G(d,p) level, and the kinetics calculations were conducted with Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The results show that the oxidation products of atmospheric chrysene are oxygenated PAHs (OPAHs) and nitro-PAHs (NPAHs), including nitro-chrysene, hydroxychrysene, hydroxychrysenone, 11-benzo[a]fluorenone and dialdehydes. Most of the products have deleterious effects on the environment and human beings due to their acute toxicity, carcinogenicity and mutagenicity. The overall rate constant for the reaction of chrysene with OH radical is 4.48 × 10-11 cm3 molecule-1 s-1 and the atmospheric lifetime of chrysene determined by OH radical is 6.4 h. The present work provided a comprehensive understanding on the degradation mechanisms and kinetics of chrysene, which could help to clarify its atmospheric fate and environmental risks.
Collapse
Affiliation(s)
- Zhezheng Ding
- Environment Research Institute, Shandong University, Qingdao, 266237, PR China
| | - Yayi Yi
- Environment Research Institute, Shandong University, Qingdao, 266237, PR China
| | - Wenxing Wang
- Environment Research Institute, Shandong University, Qingdao, 266237, PR China
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Qingdao, 266237, PR China.
| |
Collapse
|
23
|
Mai TVT, Nguyen HT, Huynh LK. Ab initio kinetic mechanism of OH-initiated atmospheric oxidation of pyrrole. Chemosphere 2021; 263:127850. [PMID: 32818845 DOI: 10.1016/j.chemosphere.2020.127850] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 07/14/2020] [Accepted: 07/19/2020] [Indexed: 06/11/2023]
Abstract
The comprehensive kinetic mechanism of the OH-initiated gas-phase oxidation of pyrrole is first theoretically reported in a broad range of conditions (T = 200-2000 K &P = 1-7600 Torr). On the potential energy surface constructed at the M06-2X/aug-cc-pVTZ level, the temperature- and pressure-dependent behaviors of the title reaction were characterized using the stochastic Rice-Ramsperger-Kassel-Marcus based Master Equation (RRKM-ME) rate model. The corrections of the hindered internal rotation and quantum tunneling treatments were included. The calculated results reveal the competition between the two distinct pathways: OH-addition and direct H-abstraction. The former channels are found favorable at low-temperature and high-pressure range (e.g., T < 900 K and P = 760 Torr) where non-Arrhenius and positive pressure-dependent behaviors of the rate constants are noticeably observed, while the latter predominate at temperatures higher than 900 K at atmospheric pressure and no pressure dependence on the rate constant is found. The predicted global rate constants are in excellent agreement with laboratory values; thus, the derived kinetic parameters are recommended for modeling/simulation of N-heterocycle-related applications in atmospheric and even in combustion conditions. Besides, pyrrole should not be considered as a persistent organic pollutant owing to its short atmospheric lifetime (∼1 h) towards OH radicals. The secondary mechanisms of the subsequent reactions of two OH-pyrrole adducts (namely, I1 and I2) with two abundant species, O2/NO, which are relevant to the atmospheric degradation process, were also investigated. It is also revealed by TD-DFT calculations that two OH-pyrrole adducts (I1 &I2), nine intermediates, Ii (i = 3-11) and four products (P1, P2, P3 and P6) can undergo photodissociation under the sunlight.
Collapse
Affiliation(s)
- Tam V-T Mai
- Molecular Science and Nano-Materials Lab, Institute for Computational Science and Technology, SBI Building, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi Minh City, Viet Nam; University of Science, 227 Nguyen Van Cu, Ward 4, District 5, Ho Chi Minh City, Viet Nam; Vietnam National University, Ho Chi Minh, Viet Nam.
| | - Hieu T Nguyen
- Molecular Science and Nano-Materials Lab, Institute for Computational Science and Technology, SBI Building, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi Minh City, Viet Nam.
| | - Lam K Huynh
- Vietnam National University, Ho Chi Minh, Viet Nam; International University, Quarter 6, Linh Trung Ward, Thu Duc District, Ho Chi Minh City, Viet Nam.
| |
Collapse
|
24
|
Son Y, Lee YM, Zoh KD. Kinetics and degradation mechanism of tris (1-chloro-2-propyl) phosphate in the UV/H 2O 2 reaction. Chemosphere 2020; 260:127461. [PMID: 32673865 DOI: 10.1016/j.chemosphere.2020.127461] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 06/11/2020] [Accepted: 06/16/2020] [Indexed: 06/11/2023]
Abstract
Tris (1-chloro-2-propyl) phosphate (TCPP) is a chlorinated organic phosphate used in various applications as a flame retardant and plasticizer. TCPP is a known suspected carcinogen and is not effectively removed by traditional water treatments such as biological, chlorination, and UV irradiation. In this study, the UV/H2O2 reaction was employed to degrade TCPP in water. TCPP was effectively degraded in the UV/H2O2 reaction by pseudofirst-order kinetics. The second-order rate constant of the reaction between the TCPP and OH radical was determined to be 4.35 (±0.13) × 108 M-1 s-1 using the competition kinetics with nitrobenzene as a reference compound. The degradation of TCPP was affected by the amount of H2O2, pH, and coexisting water components such as HCO3-, NO3-, and humic acid. Approximately 64.2% of total organic carbon (TOC) in TCPP was mineralized in 12 h during the UV/H2O2 reaction, whereas chloride (Cl-) and phosphate (PO43-) ions were identified as ionic byproducts with the recoveries of 96% chlorine (Cl) and 50% phosphorus (P). Five organic transformation products (TPs) of TCPP were also identified using LC-qTOF/MS. Considering the identified TPs, the main degradation pathway of TCPP during the UV/H2O2 reaction was found to be OH-radical-induced hydroxylation. Finally, a 70% decrease in bioluminescence inhibition in Vibrio fischeri was observed during the UV/H2O2 reaction, and the time-toxicity profile was similar to the time-peak area profile of TPs. The result of this study implies that TCPP can be efficiently removed with significant mineralization and toxicity reduction by the UV/H2O2 process.
Collapse
Affiliation(s)
- Yeongjo Son
- Department of Environmental Health Sciences, Institute of Health & Environment, School of Public Health, Seoul National University, Seoul, 08826, South Korea
| | - Young-Min Lee
- Institute of Health and Environment, Seoul National University, Seoul, South Korea
| | - Kyung-Duk Zoh
- Department of Environmental Health Sciences, Institute of Health & Environment, School of Public Health, Seoul National University, Seoul, 08826, South Korea; Institute of Health and Environment, Seoul National University, Seoul, South Korea.
| |
Collapse
|
25
|
Ding Z, Yi Y, Wang W, Zhang Q. Atmospheric oxidation of indene initiated by OH radical in the presence of O 2 and NO: A mechanistic and kinetic study. Chemosphere 2020; 259:127331. [PMID: 32650175 DOI: 10.1016/j.chemosphere.2020.127331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/02/2020] [Accepted: 06/03/2020] [Indexed: 06/11/2023]
Abstract
The atmospheric degradation of polycyclic aromatic hydrocarbons (PAHs) can generate organic pollutants that contribute to the formation of secondary organic aerosols (SOAs) and exacerbate their carcinogenicity. Indene is an example of styrene-like bicyclic hydrocarbons that are not fully aromatic. The OH-initiated atmospheric oxidation of indene in the presence of O2 and NO was investigated using quantum chemical methods at M06-2X/6-311++G(3df,2p)//M06-2X/6-311+G(d,p) level. The oxidation products are oxygenated polycyclic aromatic hydrocarbons (OPAHs) containing hydroxyindene, indenone, dialdehydes and 2-(formylmethyl)benzaldehyde. Calculation results showed that 7-indene radical, which is the precursor of various PAHs, has a high production ratio that is 35.29% in the initial reaction, indicating that the OH-initiated oxidation increase the environmental risks of indene in the atmosphere. The rate constants for the crucial elementary reactions were calculated based on Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The overall rate constant of the initial reaction is calculated to be 1.04 × 10-10 cm3 molecule-1 s-1 and the atmospheric lifetime of indene is determined as 2.74 h. This work provides a comprehensive understanding on the oxidation mechanisms of indene and the findings could help to clarify the fate of indene in the atmosphere.
Collapse
Affiliation(s)
- Zhezheng Ding
- Environment Research Institute, Shandong University, Qingdao, 266237, PR China
| | - Yayi Yi
- Environment Research Institute, Shandong University, Qingdao, 266237, PR China
| | - Wenxing Wang
- Environment Research Institute, Shandong University, Qingdao, 266237, PR China
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Qingdao, 266237, PR China.
| |
Collapse
|
26
|
Zambrano J, Park H, Min B. Enhancing electrochemical degradation of phenol at optimum pH condition with a Pt/Ti anode electrode. Environ Technol 2020; 41:3248-3259. [PMID: 31390950 DOI: 10.1080/09593330.2019.1649468] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 07/15/2019] [Indexed: 06/10/2023]
Abstract
Electrochemical phenol degradation using a platinum-coated Ti electrode was comparatively investigated at different pH levels, which were maintained over the entire operation period. Various analyses such as phenol concentration, TOC, COD, cyclic voltammetry, and total current efficiency were conducted to determine the performance of phenol degradation in the presence of Na2SO4 as the electrolyte. The phenol and COD removal rate were relatively higher at lower pH conditions (pH 3 and 5) due to high oxidant generation of OH radical and H2O2. At pH 5 condition, phenol (90 mg L-1) was completely removed after a 24-h operation. However, complete COD removal was obtained after about 250-h operation, due to byproduct formations (hydroquinone and polymers) during the phenol degradation. Cyclic voltammetry analysis indicated that acidic conditions could inhibit the oxygen-evolution reaction, causing an increase in current efficiency and a decrease in energy consumption. This study suggests that phenol-contaminated wastewater can be efficiently treated by an electrochemical process using a Pt/Ti electrode with continuously controlled lower pH conditions.Phenol oxidation by electrochemical treatment system at different pH conditions Electrochemical reactor (inside) R: reference electrode, A: Pt/Ti anode, C: Ti cathode, G: pipe to the gas bag, S: sample holder, M: magnetic stirrer.
Collapse
Affiliation(s)
- Johanna Zambrano
- Department of Environmental Science and Engineering, Kyung Hee University, Gyeonggi-do, Republic of Korea
| | - Hyunwoong Park
- School of Energy Engineering, Kyungpook National University, Daegu, Republic of Korea
| | - Booki Min
- Department of Environmental Science and Engineering, Kyung Hee University, Gyeonggi-do, Republic of Korea
| |
Collapse
|
27
|
Niveditha SV, Gandhimathi R. Flyash augmented Fe 3O 4 as a heterogeneous catalyst for degradation of stabilized landfill leachate in Fenton process. Chemosphere 2020; 242:125189. [PMID: 31675578 DOI: 10.1016/j.chemosphere.2019.125189] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 10/11/2019] [Accepted: 10/21/2019] [Indexed: 06/10/2023]
Abstract
In this study magnetite (Fe3O4) was augmented over coal flyash and analyzed for the effectiveness as a catalyst in heterogeneous Fenton process for the degradation of persistent organic pollutant present in stabilized landfill leachate. Fe3O4 and flyash augmented Fe3O4 was prepared by simple chemical precipitation method and both had magnetic nature. XRD, FTIR and SEM with EDX characterization were consummated for both catalysts. The Fenton experiments were performed in batch mode and to identify the optimal operating condition for effective COD removal the leachate pH, catalysts and H2O2 dosages were varied. The reusability of the catalysts was studied. To understand the degradation mechanism adsorption study, Fenton oxidation of benzoic acid and scavenging experiments with KI and NaF were performed. It was witnessed that flyash augmented Fe3O4 exhibited 84.7% of COD degradation which was 12.3% of higher removal efficiency than Fe3O4 at optimum pH 3, 0.05 M H2O2 and 1000 mg/L of catalyst dosage in 100 min reaction time. This flyash augmented Fe3O4 showed 68% of TOC removal and good increment in biodegradability. Poor NH3-N removal was observed in the Fenton treatment process. Decrease in aromaticity was found based on SUVA254 value and also indicated the removal of organic matter. Similarly, reusability and stability were higher than Fe3O4. The results indicate that flyash augmented Fe3O4 is a competent catalyst in heterogeneous Fenton process for treatment of mature leachate. The usage of waste material flyash with Fe3O4 decreases the co-aggregation of Fe3O4 and improves the catalytic performance.
Collapse
Affiliation(s)
- S V Niveditha
- Department of Civil Engineering, National Institute of Technology, Tiruchirappalli, Thuvakudi, Tamil Nadu, 620 015, India
| | - R Gandhimathi
- Department of Civil Engineering, National Institute of Technology, Tiruchirappalli, Thuvakudi, Tamil Nadu, 620 015, India.
| |
Collapse
|
28
|
Liao Z, Zeng M, Wang L. Atmospheric oxidation mechansim of polychlorinated biphenyls (PCBs) initiated by OH radicals. Chemosphere 2020; 240:124756. [PMID: 31563106 DOI: 10.1016/j.chemosphere.2019.124756] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 09/03/2019] [Accepted: 09/03/2019] [Indexed: 05/16/2023]
Abstract
Long-range atmospheric transport (LRAT) is the main route for circulating polychlorinated biphenyls (PCBs) from sources to sinks. In the atmosphere, PCBs containing six and less chlorine substitutions exist mainly as vapour, which can be oxidized by OH radical. Here, using quantum chemistry and transition state theory, we calculated the rate coefficients for reactions of OH radical with selected PCBs. The predicted rate coefficients agree with the available experimental values within a factor of 3. Calculations show that all PCBs considered here are persistent with their half-lives longer than 24 h. Reactions of PCBs with OH radical start with OH addition to the phenyl rings, forming PCB-n-OH adducts. Fate of biphenyl-n-OH (BP-n-OH, n = 2, 3, 4) adducts in the atmosphere is investigated. Calculations show that these radical adducts react similarly to benzene-OH adducts, forming hydroxybiphenyl (HO-BP) as main product and bicyclic radicals as minor products in their reaction with O2. Effective rates of reaction with O2 in the atmosphere are relatively slow, ∼1400, ∼45000, and ∼800 s-1 for BP-2-OH, BP-3-OH, and BP-4-OH, respectively. This suggests considerable reactions between BP-n-OH adducts and NO2, forming nitrobiphenyls. The bicyclic radicals from BP-n-OH + O2 would further transform to highly oxidized products as observed in a previous study. PCB-OH adducts react similarly as BP-n-OH radicals. For the three PCB-OH radicals considered here, their reactions with O2 also form HO-PCBs and bicyclic radicals.
Collapse
Affiliation(s)
- Zhihong Liao
- School of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou, 510640, China
| | - Min Zeng
- School of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou, 510640, China
| | - Liming Wang
- School of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou, 510640, China; Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, South China University of Technology, Guangzhou, 510006, China.
| |
Collapse
|
29
|
Cho YC, Lin RY, Lin YP. Degradation of 2,4-dichlorophenol by CuO-activated peroxydisulfate: Importance of surface-bound radicals and reaction kinetics. Sci Total Environ 2020; 699:134379. [PMID: 31522041 DOI: 10.1016/j.scitotenv.2019.134379] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 09/06/2019] [Accepted: 09/08/2019] [Indexed: 06/10/2023]
Abstract
Peroxydisulfate (PDS, S2O82-) is a promising oxidant for water treatment and contaminated groundwater remediation. It requires activation to generate sulfate radical (SO4-) and hydroxyl radical (OH) for indirect oxidation of organic pollutants. Recently, efforts were devoted to developing PDS activation systems for direct oxidation of organic pollutants without producing radicals. However, the mechanism was still ambiguous and the kinetics was either not quantified or empirical in nature. In this research, we examined the activation of PDS by CuO for the degradation of 2,4-dichlorophenol (2,4-DCP). Dual-compound control experiments, radical scavenging tests and electron paramagnetic resonance (EPR) studies showed that surface-bound OH generated from the adsorbed PDS was the main reactive species responsible for the degradation of 2,4-DCP. A kinetic model considering the important reaction steps, including the adsorption of PDS onto CuO, activation of adsorbed PDS to form surface-bound SO4- and then surface-bound OH, and degradation of 2,4-DCP by surface-bound OH, was developed to better elucidate the reaction kinetics. The results suggested that the overall reaction kinetics of 2,4-DCP degradation was regulated by the adsorption of PDS onto CuO and the electron transfer between surface Cu and adsorbed PDS to form surface-bound SO4-. The developed kinetic model could serve as a framework to characterize other persulfate oxidation systems relying on surface-bound radicals.
Collapse
Affiliation(s)
- Yi-Chin Cho
- Graduate Institute of Environmental Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Ru-Yi Lin
- Graduate Institute of Environmental Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Yi-Pin Lin
- Graduate Institute of Environmental Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan; NTU Research Center for Future Earth, National Taiwan University, Taipei, Taiwan.
| |
Collapse
|
30
|
Yasui K, Tuziuti T, Kanematsu W. Mechanism of OH radical production from ozone bubbles in water after stopping cavitation. Ultrason Sonochem 2019; 58:104707. [PMID: 31450352 DOI: 10.1016/j.ultsonch.2019.104707] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 07/16/2019] [Accepted: 07/23/2019] [Indexed: 06/10/2023]
Abstract
It has been experimentally reported that OH radicals are produced from ozone microbubbles even after stopping cavitation. Microbubbles are mostly produced using acoustic or hydrodynamic cavitation. In the present paper, numerical simulations of chemical reactions inside an ozone bubble and an oxygen bubble are performed during and after acoustic cavitation in order to study the mechanism of OH radical production. The results have indicated that less than one molecule of OH radicals is produced from a dissolving ozone bubble after stopping cavitation when local pH near the bubble wall is <8. On the other hand, more than 108 or 106 molecules of H2O2 are produced inside an ozone or oxygen microbubble, respectively, in water during acoustic cavitation per violent collapse. It suggests that OH radicals are possibly produced by the chemical reaction of H2O2 with O3 in the liquid phase even after stopping cavitation. Furthermore, in strongly acidic conditions (pH < 5), the reaction of H2O2 with O3 in the liquid phase is relatively slow, and OH production considerably continues after stopping cavitation. This may be the reason for the enhanced OH signals in strongly acidic conditions observed experimentally after stopping cavitation.
Collapse
Affiliation(s)
- Kyuichi Yasui
- National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan.
| | - Toru Tuziuti
- National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan
| | - Wataru Kanematsu
- National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan
| |
Collapse
|
31
|
Seo C, Shin J, Lee M, Lee W, Yoom H, Son H, Jang S, Lee Y. Elimination efficiency of organic UV filters during ozonation and UV/H 2O 2 treatment of drinking water and wastewater effluent. Chemosphere 2019; 230:248-257. [PMID: 31103871 DOI: 10.1016/j.chemosphere.2019.05.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 05/01/2019] [Accepted: 05/03/2019] [Indexed: 06/09/2023]
Abstract
The efficiency of elimination of organic UV filters by ozonation and UV254nm/H2O2 processes was assessed and predicted in simulated treatments of sewage-impaired drinking water and wastewater effluent in bench-scale experiments. Second-order rate constants (k) for the reactions of the eight UV filters with ozone and OH were determined by quantum chemical calculations and competition kinetics methods, respectively. The UV filters containing phenolic (ethylhexyl-salicylate, homosalate, and benzophenone-3) and olefinic moieties (4-methylbenzylidene-camphor, benzyl-cinnamate, and 2-ethylhexyl-4-methoxycinnamate) showed high ozone reactivity (k ≥ 8 × 104 M-1s-1 at pH 7), while those without such electron-rich moieties (isoamyl-benzoate and benzophenone) were ozone-refractory. All the UV filters showed high OH reactivity (k ≥ 6.2 × 109 M-1s-1). In concordance with the rate constant information, the phenolic and olefinic UV filters were efficiently eliminated by ozone treatment, requiring specific ozone doses of <0.5 mgO3/mgDOC for ∼100% elimination. The UV filters were eliminated by ≤ 38% at a UV fluence of 1500 mJ/cm2 in the UV254nm-only treatment. Rapid photoisomerisation between the E and Z geometric isomers was observed for the olefinic UV filter, benzyl-cinnamate. The addition of H2O2 (10 mg/L) greatly enhanced the elimination of all UV filters, indicating that OH was the main contributor to their elimination in the UV254nm/H2O2 treatment. A chemical kinetics approach developed previously for ozonation and UV/H2O2 processes was shown to predict the elimination of the UV filters in the tested water matrices reasonably well, demonstrating that the chemical kinetics method can be used for a priori prediction of micropollutant elimination in oxidative treatment processes for potable reuse of municipal wastewater effluents.
Collapse
Affiliation(s)
- Changdong Seo
- Busan Water Quality Institute, Busan, Republic of Korea; Department of Bioenvironmental Energy, Pusan National University, Pusan, Republic of Korea
| | - Jaedon Shin
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Minju Lee
- Department of Chemistry, University of Washington, Seattle, WA, USA
| | - Woongbae Lee
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea
| | - Hoonsik Yoom
- Busan Water Quality Institute, Busan, Republic of Korea
| | - Heejong Son
- Busan Water Quality Institute, Busan, Republic of Korea
| | - Seongho Jang
- Department of Bioenvironmental Energy, Pusan National University, Pusan, Republic of Korea
| | - Yunho Lee
- School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea.
| |
Collapse
|
32
|
Yasui K, Tuziuti T, Kanematsu W. High temperature and pressure inside a dissolving oxygen nanobubble. Ultrason Sonochem 2019; 55:308-312. [PMID: 30686604 DOI: 10.1016/j.ultsonch.2019.01.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 12/17/2018] [Accepted: 01/12/2019] [Indexed: 06/09/2023]
Abstract
Numerical simulations of dissolution of an oxygen (O2) nanobubble into water without dynamic stimuli have been performed in order to study the possibility of OH radical formation from oxygen nanobubbles experimentally reported by Liu et al. (2016). The dissolution of an oxygen nanobubble is much faster than that of an air nanobubble due to higher solubility of oxygen in water. However, the temperature and pressure inside an oxygen nanobubble at the final moment of the bubble dissolution are about 2800 K and 4.5 GPa, respectively, which are slightly lower than those inside an air nanobubble due to higher thermal conductivity of oxygen. A few molecules of OH radicals may be formed per 107 bubbles according to the numerical simulation. The estimated production rate of OH radicals is 13 orders of magnitude smaller than the experimentally reported one.
Collapse
Affiliation(s)
- Kyuichi Yasui
- National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan.
| | - Toru Tuziuti
- National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan
| | - Wataru Kanematsu
- National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan
| |
Collapse
|
33
|
Ding Z, Yi Y, Zhang Q, Zhuang T. Theoretical investigation on atmospheric oxidation of fluorene initiated by OH radical. Sci Total Environ 2019; 669:920-929. [PMID: 30897445 DOI: 10.1016/j.scitotenv.2019.02.400] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 02/21/2019] [Accepted: 02/25/2019] [Indexed: 05/18/2023]
Abstract
Atmospheric oxidation of fluorene and its derivatives initiated by OH radicals was investigated theoretically with quantum chemical calculation methods [M06-2X/6-311++G(3df,2p)//M06-2X/6-311+G(d,p)]. It revealed that the OH addition pathways form hydroxyfluorene and ring-opening product dialdehyde while the H abstraction pathways lead to the formation of 9-fluorenone. Subsequent oxidation of 9-fluorenone has considerable potential to form dibenzo-p-dioxin and nitrofluorenone according to the present calculation results. The atmospheric lifetime of fluorene relative to the reactions with OH radicals is deduced to be 12.51 h based on the calculated overall rate constant (2.29 × 10-11 cm3 molecule-1 s-1) at 298 K and 1 atm. The oxidation products of fluorene in the atmosphere are generally more toxic and persistent. This work provides a comprehensive explanation for atmospheric oxidation processes of fluorene and facilitates clarifying its environmental risks.
Collapse
Affiliation(s)
- Zhezheng Ding
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Yayi Yi
- Environment Research Institute, Shandong University, Qingdao 266237, PR China
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Qingdao 266237, PR China; Jinan Environmental Research Academy, Jinan 250102, PR China.
| | - Tao Zhuang
- Jinan Environmental Research Academy, Jinan 250102, PR China
| |
Collapse
|
34
|
Kim T, Kim TK, Zoh KD. Degradation kinetics and pathways of β-cyclocitral and β-ionone during UV photolysis and UV/chlorination reactions. J Environ Manage 2019; 239:8-16. [PMID: 30877971 DOI: 10.1016/j.jenvman.2019.03.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 02/12/2019] [Accepted: 03/06/2019] [Indexed: 06/09/2023]
Abstract
β-cyclocitral and β-ionone are ones of major algal odorants produced by oxidation of the β-carotene that exists in algae cells. These compounds degraded the quality of drinking water therefore it needed to be treated in drinking water treatment by advanced oxidation processes. In this study, UV photolysis and UV-chlorination reactions along with chlorination to remove these odorants in water were compared. Kinetics of three reactions were well fitted at pseudo-first order model. Among three reactions, UV-chlorination was the most effective due to generation of OH and Cl radicals. β-ionone showed faster degradation compared to β-cyclocitral due to the existence of double bond in the alkyl carbon chain. In addition, radical contributions of degradation of odorants were examined. During UV-chlorination, UV photolysis contributed around 50% of removal for two odorants. OH radical took part of 36% removal of β-ionone and 50% removal of β-cyclocitral. Unlike β-ionone, β-cyclocitral was not degraded by reactive chlorine species during UV-chlorination. Acidic pH was favorable for UV-chlorination due to different quantum yield and radical scavenging effect by chlorine species. Formation of trace amount of chloroform was observed during UV-chlorination. The methyl ketone group of β-ionone was the main site for chloroform production. Several byproducts during UV photolysis and UV-chlorination of β-ionone were identified by GC-MS, and these were degraded with further reaction by UV-induced isomerization, OH radical, and bond scission mechanisms. β-cyclocitral was formed as byproducts during UV-chlorination of β-ionone. Based on degradation byproducts, the degradation pathways of β-ionone and β-cyclocitral of UV photolysis and UV-chlorination were suggested based on the identified byproducts. This study showed UV-chlorination process can be applied for degrading odorants like β-cyclocitral and β-ionone.
Collapse
Affiliation(s)
- Taeyeon Kim
- Department of Environmental Health Sciences, School of Public Health, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea
| | - Tae-Kyoung Kim
- Department of Environmental Health Sciences, School of Public Health, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea
| | - Kyung-Duk Zoh
- Department of Environmental Health Sciences, School of Public Health, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea.
| |
Collapse
|
35
|
Mattei C, Wortham H, Quivet E. Heterogeneous degradation of pesticides by OH radicals in the atmosphere: Influence of humidity and particle type on the kinetics. Sci Total Environ 2019; 664:1084-1094. [PMID: 30901782 DOI: 10.1016/j.scitotenv.2019.02.038] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 01/25/2019] [Accepted: 02/02/2019] [Indexed: 06/09/2023]
Abstract
Pesticides can be adsorbed on the surface of atmospheric aerosol, depending on their physicochemical properties. They can be degraded by atmospheric oxidants such as OH radicals but the influence of some environmental parameters on the degradation kinetics, especially relative humidity and particle surface type, is not well understood. Heterogeneous degradation by OH radicals of eight commonly used pesticides (i.e., difenoconazole, tetraconazole, cyprodinil, fipronil, oxadiazon, pendimethalin, deltamethrin, and permethrin) adsorbed on hydrophobic and hydrophilic silicas at a relative humidity ranging from 0% to 70% was studied. Under experimental conditions, only cyprodinil, deltamethrin, permethrin, and pendimethalin were degraded by OH radical in atmospheric relevant concentration. Second-order kinetic constants calculated for the pesticides degraded by OH radicals ranged from (1.93 ± 0.61) × 10-13 cm3 molecule-1 s-1 (permethrin, hydrophobic silica, 30% RH) to (4.08 ± 0.27) × 10-12 cm3 molecule-1 s-1 (pendimethalin, hydrophilic silica, 0% RH). Results obtained can contribute to improve the understanding of the atmospheric fate of pesticides and other semi-volatile organic compounds in the particulate phase and they highlight the importance of taking humidity and particle type into account for the determination of pesticides atmospheric half-lives.
Collapse
Affiliation(s)
- Coraline Mattei
- Aix Marseille Univ, CNRS, LCE, Marseille, France; French Environment and Energy Management Agency, 20, avenue du Grésillé, BP 90406, 49004 Angers Cedex 01, France
| | | | | |
Collapse
|
36
|
Dang J, Tian S, Zhang Q. Mechanism and kinetics studies of the atmospheric oxidation of p,p'-Dicofol by OH and NO 3 radicals. Chemosphere 2019; 219:645-654. [PMID: 30557720 DOI: 10.1016/j.chemosphere.2018.12.048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 12/03/2018] [Accepted: 12/06/2018] [Indexed: 06/09/2023]
Abstract
As an effective organochlorine pesticide, Dicofol has been extensively applied in more than 30 countries for protecting over 60 different crops. Considering its large consumption and potential adverse effect on human health (endocrine disrupting and carcinogenicity), the fate of Dicofol sprayed into the air is of public concern. In this study, we conducted a comprehensive study on the reaction mechanisms of p,p'-Dicofol with OH and NO3 radicals using DFT method. Comparing the abstrations by OH and NO3 radical, OH and NO3 radical addition reactions are predominant due to the lower potential barriers and stronger heat release. The phenolic substances (P1P5), epoxides (P11 and P15), dialdehyde (P13) and other species (P8, P9, P10 and P14) are generated by OH additions and their subsequent reactions while OH abstraction reactions produce DCBP, P7 and chlorphenyl radical. Particularly, NO3 additions and their subsequent reactions yield dialdehydes (P16 and P17) and 2,8-DCDD, which is the first report of the generation of dioxin from atmospheric oxidation of p,p'-Dicofol. Additionally, based on the structure optimization and energy calculation, rate constants and Arrhenius formulas of the elementary reactions of p,p'-Dicofol with OH and NO3 radicals were obtained over the temperature range of 280-380 K and at 1 atm. The rate constants for the reactions of p,p'-Dicofol with OH and NO3 radicals are 1.51 × 10-12 and 8.88 × 10-14 cm3 molecule-1 s-1, respectively. The lifetime (τTotal) of p,p'-Dicofol determined by the reactions of OH and NO3 radical is 5.86 h, indicating a potential long-range transport in the atmosphere.
Collapse
Affiliation(s)
- Juan Dang
- Key Laboratory of Western China's Environmental Systems of the Ministry of Education, Key Laboratory of Environmental Pollution Prediction and Control of Gansu Province, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou, 730000, China; Environment Research Institute, Shandong University, Jinan, 250100, China.
| | - Shuai Tian
- School of Energy and Power Engineering, Shandong University, Jinan, Shandong, 250061, China.
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University, Jinan, 250100, China
| |
Collapse
|
37
|
Tokuhashi K, Takizawa K, Kondo S. Rate constants for the reactions of OH radicals with CF 3CX=CY 2 (X = H, F, CF 3, Y = H, F, Cl). Environ Sci Pollut Res Int 2018; 25:15204-15215. [PMID: 29560593 DOI: 10.1007/s11356-018-1700-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 03/05/2018] [Indexed: 06/08/2023]
Abstract
The rate constants of OH radicals with CF3CF=CCl2, CF3CH=CF2, CF3CF=CH2, CF3CH=CH2, and (CF3)2C=CH2 have been measured over the temperature range 250-430 K. Kinetic measurements have been carried out using flash photolysis and laser photolysis methods combined respectively with laser-induced fluorescence technique. The Arrhenius rate parameters have been determined as k(CF3CF=CCl2) = (6.50 ± 0.22) × 10-13∙exp[(200 ± 10)/T], k(CF3CH=CF2) = (4.85 ± 0.14) × 10-13∙exp[(120 ± 10)/T], k(CF3CF=CH2) = (1.54 ± 0.03) × 10-12∙exp[- (100 ± 10)/T], k(CF3CH=CH2) = (1.06 ± 0.02) × 10-12∙exp[(80 ± 10)/T], and k((CF3)2C=CH2) = (8.75 ± 0.23) × 10-13∙exp[- (20 ± 10)/T] cm3 molecule-1 s-1. Infrared absorption spectra of the halogenated alkenes have been measured at room temperature. The atmospheric lifetime, global warming potential, ozone depleting potential, and photochemical ozone creation potential have been estimated. The change in the reactivity of halogenated alkenes by the substitution has been examined by considering the structure containing the atoms or atomic groups attached to the carbons on both sides of the double bond.
Collapse
Affiliation(s)
- Kazuaki Tokuhashi
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
| | - Kenji Takizawa
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan.
| | - Shigeo Kondo
- National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan
| |
Collapse
|
38
|
Zhang X, Barraza KM, Beauchamp JL. Cholesterol provides nonsacrificial protection of membrane lipids from chemical damage at air-water interface. Proc Natl Acad Sci U S A 2018; 115:3255-60. [PMID: 29507237 DOI: 10.1073/pnas.1722323115] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The role of cholesterol in bilayer and monolayer lipid membranes has been of great interest. On the biophysical front, cholesterol significantly increases the order of the lipid packing, lowers the membrane permeability, and maintains membrane fluidity by forming liquid-ordered-phase lipid rafts. However, direct observation of any influence on membrane chemistry related to these cholesterol-induced physical properties has been absent. Here we report that the addition of 30 mol % cholesterol to 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (POPG) monolayers at the air-water interface greatly reduces the oxidation and ester linkage cleavage chemistries initiated by potent chemicals such as OH radicals and HCl vapor, respectively. These results shed light on the indispensable chemoprotective function of cholesterol in lipid membranes. Another significant finding is that OH oxidation of unsaturated lipids generates Criegee intermediate, which is an important radical involved in many atmospheric processes.
Collapse
|
39
|
Chen H, Hu R, Xie P, Xing X, Ling L, Li Z, Wang F, Wang Y, Liu J, Liu W. A hydroxyl radical detection system using gas expansion and fast gating laser-induced fluorescence techniques. J Environ Sci (China) 2018; 65:190-200. [PMID: 29548391 DOI: 10.1016/j.jes.2017.03.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/17/2017] [Accepted: 03/10/2017] [Indexed: 06/08/2023]
Abstract
An OH radical measurement instrument based on Fluorescence Assay by Gas Expansion (FAGE) has been developed in our laboratory. Ambient air is introduced into a low-pressure fluorescence cell through a pinhole aperture and irradiated by a dye laser at a high repetition rate of 8.5kHz. The OH radical is both excited and detected at 308nm using A-X(0,0) band. To satisfy the high efficiency needs of fluorescence collection and detection, a 4-lens optical system and a self-designed gated photomultiplier (PMT) is used, and gating is actualized by switching the voltage applied on the PMT dynodes. A micro channel photomultiplier (MCP) is also prepared for fluorescence detection. Then the weak signal is accumulated by a photon counter in a specific timing. The OH radical excitation spectrum range in the wavelength of 307.82-308.2nm is detected and the excited line for OH detection is determined to be Q1(2) line. The calibration of the FAGE system is researched by using simultaneous photolysis of H2O and O2. The minimum detection limit of the instrument using gated PMT is determined to be 9.4×105molecules/cm3, and the sensitivity is 9.5×10-7cps/(OH·cm-3), with a signal-to-noise ratio of 2 and an integration time of 60sec, while OH detection limit and the detection sensitivity using MCP is calculated to be 1.6×105molecules/cm3 and 2.3×10-6cps/(OH·cm-3). The laboratory OH radical measurement is carried out and results show that the proposed system can be used for atmospheric OH radical measurement.
Collapse
Affiliation(s)
- Hao Chen
- Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230027, China; Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China.
| | - Renzhi Hu
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China.
| | - Pinhua Xie
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China; CAS Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361000, China.
| | - Xingbiao Xing
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
| | - Liuyi Ling
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China; Institute of Electric and Information Technology, Anhui University of Science and Technology, Huainan 232001, China
| | - Zhiyan Li
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
| | - Fengyang Wang
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
| | - Yihui Wang
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
| | - Jianguo Liu
- Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
| | - Wenqing Liu
- Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230027, China; Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
| |
Collapse
|
40
|
Baruah SD, Gour NK, Sarma PJ, Deka RC. OH-initiated mechanistic pathways and kinetics of camphene and fate of product radical: a DFT approach. Environ Sci Pollut Res Int 2018; 25:2147-2156. [PMID: 29116529 DOI: 10.1007/s11356-017-0646-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 10/30/2017] [Indexed: 06/07/2023]
Abstract
Present manuscript represents the DFT studies on the oxidation reaction of camphene initiated by OH radical and fate of product radicals using M06-2X functional along with 6-31+G(d,p) basis set. Intrinsic reaction calculation is done for transition states involving OH-addition reactions which proceed via reaction complexes proceeding to the formation of transition states. The rate constant calculated by using canonical transition state theory at 298 K and 1 atm is found to be 5.67 × 10-11 cm3 molecule-1 s-1 which is in good agreement with the experimental rate constant. The atmospheric lifetime of the titled molecule has also been reported in our work.
Collapse
Affiliation(s)
- Satyajit Dey Baruah
- Department of Chemical Sciences, Tezpur University Tezpur, Napaam, Assam, 784028, India
| | - Nand Kishor Gour
- Department of Chemical Sciences, Tezpur University Tezpur, Napaam, Assam, 784028, India.
| | - Plaban Jyoti Sarma
- Department of Chemical Sciences, Tezpur University Tezpur, Napaam, Assam, 784028, India
| | - Ramesh Chandra Deka
- Department of Chemical Sciences, Tezpur University Tezpur, Napaam, Assam, 784028, India.
| |
Collapse
|
41
|
Pozdnyakov IP, Romanova TE, Cai X, Salomatova VA, Plyusnin VF, Na P, Shuvaeva OV. Near-UV photooxidation of As(III) by iron species in the presence of fulvic acid. Chemosphere 2017; 181:337-342. [PMID: 28456035 DOI: 10.1016/j.chemosphere.2017.04.103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 04/05/2017] [Accepted: 04/23/2017] [Indexed: 06/07/2023]
Abstract
Photooxidation of As(III) in ternary As(III) - Fe(III) - Fulvic acid system at pH 4 was investigated by optical spectroscopy, steady-state photolysis (365 nm) and atomic-emission spectrometry with inductively coupled plasma techniques. It was found that at all values of [FA]/[Fe] ratio the main photoactive species is OH radical formed by photolysis of Fe(III) hydroxocomplexes. Addition of fulvic acid leads to mainly negative effect on As(III) photooxidation due to the following reasons: (i) slow dark reduction of photoactive Fe(III) species with formation of scattering particles and photoinert Fe(II) species; (ii) formation of photoreductive Fe(III)-FA complexes incapable to oxidize As(III), (iii) competition of both FA and Fe(III)-FA complexes for UVA quanta with FeOH2+ complex and for OH radicals with As(III). Aging of ternary system is also very important parameter leading to one order decrease of quantum yields of both Fe(II) formation and As(III) photooxidation.
Collapse
Affiliation(s)
- Ivan P Pozdnyakov
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 3 Institutskaya St., 630090 Novosibirsk, Russian Federation; Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk, Russian Federation.
| | - Tamara E Romanova
- Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk, Russian Federation; Nikolaev Institute of Inorganic Chemistry, 3 Acad. Lavrentiev Ave., 630090 Novosibirsk, Russian Federation
| | - Xiaojiao Cai
- Institute of Chemical Technology, Tianjin University, 92 Weijin Rd, 300072 Nankai, Tianjin, China
| | - Victoria A Salomatova
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 3 Institutskaya St., 630090 Novosibirsk, Russian Federation
| | - Victor F Plyusnin
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 3 Institutskaya St., 630090 Novosibirsk, Russian Federation; Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk, Russian Federation
| | - Ping Na
- Institute of Chemical Technology, Tianjin University, 92 Weijin Rd, 300072 Nankai, Tianjin, China
| | - Olga V Shuvaeva
- Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk, Russian Federation; Nikolaev Institute of Inorganic Chemistry, 3 Acad. Lavrentiev Ave., 630090 Novosibirsk, Russian Federation
| |
Collapse
|
42
|
Zeng X, Chen J, Qu R, Pan X, Wang Z. The OH-initiated atmospheric chemical reactions of polyfluorinated dibenzofurans and polychlorinated dibenzofurans: A comparative theoretical study. Chemosphere 2017; 168:10-17. [PMID: 27776226 DOI: 10.1016/j.chemosphere.2016.10.062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Revised: 10/16/2016] [Accepted: 10/18/2016] [Indexed: 06/06/2023]
Abstract
The atmospheric chemical reactions of some polyfluorinated dibenzofurans (PFDFs) and polychlorinated dibenzofurans (PCDFs), initiated by OH radical, were investigated by performing theoretical calculations using density functional theory (DFT) and B3LYP/6-311++G(2df,p) method. The obtained results indicate that OH addition reactions of PFDFs and PCDFs occurring at C1∼4 and CA sites are thermodynamic spontaneous changes and the branching ratio of the PF(C)DF-OH adducts is decided primarily by kinetic factor. The OH addition reactions of PFDFs taking place at fluorinated C1∼4 positions are kinetically comparable with those occurring at nonfluorinated C1∼4 positions, while OH addition reactions of PCDFs occurring at chlorinated C1∼4 sites are negligible. The total rate constants of the addition reactions of PFDFs or PCDFs become smaller with consecutive fluorination or chlorination, and substituting at C1 position has more adverse effects than substitution at other sites. The succedent O2 addition reactions of PF(C)DF-OH adducts are thermodynamic nonspontaneous processes under the atmospheric conditions, and have high Gibbs free energies of activation (ΔrG≠). The substituted dibenzofuranols are the primary oxidation products for PCDFs under the atmospheric conditions. However, other oxidative products may also be available for PFDFs besides substituted dibenzofuranols.
Collapse
Affiliation(s)
- Xiaolan Zeng
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China; College of Chemistry and Chemical Engineering, Xinyang Normal University, Henan, Xinyang, 464000, China
| | - Jing Chen
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China
| | - Ruijuan Qu
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China
| | - Xiaoxue Pan
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China
| | - Zunyao Wang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China.
| |
Collapse
|
43
|
Tafer R, Sleiman M, Boulkamh A, Richard C. Photomineralization of aqueous salicylic acids. Photoproducts characterization and formation of light induced secondary OH precursors (LIS-OH). Water Res 2016; 106:496-506. [PMID: 27770726 DOI: 10.1016/j.watres.2016.10.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 10/14/2016] [Accepted: 10/15/2016] [Indexed: 06/06/2023]
Abstract
The photolysis of aqueous 5-chlorosalicylic acid (ClSA) and dihydroxybenzoic acid (DHBA), its main photoproduct, was studied to determine the extent of degradation caused by simulated solar light. Photoproducts identification was achieved using high resolution LC-MS and GC-MS. About 40 photoproducts from C19 to C1 were characterized, including a dihydroxycyclopentadienic acid, a ring contraction photoproduct, and numerous carbonyls and carboxylic acid derivatives that were detected thanks to derivatization. UV-visible spectral monitoring of the reactions revealed that ClSA and DHBA underwent photobleaching after developing a temporarily featureless absorbance between 300 and 500 nm. Measurement of OH radicals using terephtalic acid as a probe showed that OH radicals were generated with an average rate of 7 × 10-9 M s-1 and a total cumulated concentration of 10-3 M, corresponding to ∼ 5-fold the initial concentration of DHBA. Furthermore, TOC analysis indicated that significant mineralization (51-90%) occurred. These findings are consistent with the formation of light induced secondary OH (LIS-OH) precursors such as featureless long wavelength absorbing compounds as well as non-absorbing hydroperoxides. The formation of LIS-OH illustrated here may also take place in the aqueous photodegradation of other substituted phenols likely present in dissolved organic matter and humic substructures, it deserves to be studied in more details.
Collapse
Affiliation(s)
- R Tafer
- Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont Ferrand, BP 10448, F-63000, Clermont-Ferrand, France; CNRS, UMR 6296, ICCF, F-63178, Aubiere, France; Université des Frères Mentouri, Constantine 1, Laboratoire des Techniques Innovantes de Préservation de l'Environnement, Route de Ain El Bey, Constantine, 25017, Algeria
| | - M Sleiman
- Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont Ferrand, BP 10448, F-63000, Clermont-Ferrand, France; Université Clermont Auvergne, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000, Clermont-Ferrand, France
| | - A Boulkamh
- Université des Frères Mentouri, Constantine 1, Laboratoire des Techniques Innovantes de Préservation de l'Environnement, Route de Ain El Bey, Constantine, 25017, Algeria
| | - C Richard
- Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont Ferrand, BP 10448, F-63000, Clermont-Ferrand, France; CNRS, UMR 6296, ICCF, F-63178, Aubiere, France.
| |
Collapse
|
44
|
He M, Li X, Zhang S, Sun J, Cao H, Wang W. Mechanistic and kinetic investigation on OH-initiated oxidation of tetrabromobisphenol A. Chemosphere 2016; 153:262-269. [PMID: 27018518 DOI: 10.1016/j.chemosphere.2016.03.043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 02/17/2016] [Accepted: 03/10/2016] [Indexed: 06/05/2023]
Abstract
Detailed mechanism of the OH-initiated transformation of tetrabromobisphenol A (TBBPA) has been investigated by quantum chemical methods in this paper. Abstraction reactions of hydrogen atoms from the OH groups and CH3 groups of TBBPA are the dominant pathways of the initial reactions. The produced phenolic-type radical and alkyl-type radical may transfer to 4,4'-(ethene-1,1-diyl)bis(2,6-dibromophenol), 4-acetyl-2,6-dibromophenol and 2,6-dibromobenzoquinone at high temperature. In water, major products are 2,6-dibromo-p-hydroquinone, 4-isopropylene-2,6-dibromophenol and 4-(2-hydroxyisopropyl)-2,6-dibromophenol resulting from the addition reactions. Total rate constants of the initial reaction are 1.02 × 10(-12) cm(3) molecule(-1) s(-1) in gas phase and 1.93 × 10(-12) cm(3) molecule(-1) s(-1) in water at 298 K.
Collapse
Affiliation(s)
- Maoxia He
- Environment Research Institute, Shandong University, Jinan, 250100, PR China
| | - Xin Li
- Environment Research Institute, Shandong University, Jinan, 250100, PR China
| | - Shiqing Zhang
- Environment Research Institute, Shandong University, Jinan, 250100, PR China
| | - Jianfei Sun
- Environment Research Institute, Shandong University, Jinan, 250100, PR China
| | - Haijie Cao
- Environment Research Institute, Shandong University, Jinan, 250100, PR China.
| | - Wenxing Wang
- Environment Research Institute, Shandong University, Jinan, 250100, PR China
| |
Collapse
|
45
|
Lee K, Ku H, Pak D. OH radical generation in a photocatalytic reactor using TiO2 nanotube plates. Chemosphere 2016; 149:114-120. [PMID: 26855214 DOI: 10.1016/j.chemosphere.2016.01.103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 01/11/2016] [Accepted: 01/24/2016] [Indexed: 06/05/2023]
Abstract
In order to use TiO2 nanotubes grown on a Ti plate as a photocatalyst, self-organized oxide nanotube layers were grown by anodization in a glycerol based electrolyte. The ultimate conditions for the synthesis of the TiO2 nanotube array on the Ti plate were investigated by comparing the morphology, length, and inner diameter of the nanotubes. They were significantly affected by the applied anodic voltage, anodization time, and composition of the electrolyte such as the water and fluoride ion concentration. The crystallographic structures of TiO2 nanotubes before and after annealing were compared. The photocatalytic reactor used in this study consisted of two parallel and closely spaced TiO2 nanotube plates. The plates were squares while a UV lamp was inserted perpendicularly to them. OH radical generation in the photocatalytic reactor was monitored by using a probe compound, parachlorobenzoate (pCBA). The steady state OH radical concentration was compared depending on the length of nanotubes and crystallographic structure. The longer the nanotubes, the higher the steady state OH radical concentration.
Collapse
Affiliation(s)
- Kangpyung Lee
- Graduate School of Energy and Environment, Seoul National University of Science and Technology, 232 Gongneungro, Nowon-gu, Seoul, South Korea
| | - Haemin Ku
- Graduate School of Energy and Environment, Seoul National University of Science and Technology, 232 Gongneungro, Nowon-gu, Seoul, South Korea
| | - Daewon Pak
- Graduate School of Energy and Environment, Seoul National University of Science and Technology, 232 Gongneungro, Nowon-gu, Seoul, South Korea.
| |
Collapse
|
46
|
Singh G, Mohanty BP, Saini GSS. Structure, spectra and antioxidant action of ascorbic acid studied by density functional theory, Raman spectroscopic and nuclear magnetic resonance techniques. Spectrochim Acta A Mol Biomol Spectrosc 2016; 155:61-74. [PMID: 26580511 DOI: 10.1016/j.saa.2015.11.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 10/27/2015] [Accepted: 11/03/2015] [Indexed: 06/05/2023]
Abstract
Structure, vibrational and nuclear magnetic resonance spectra, and antioxidant action of ascorbic acid towards hydroxyl radicals have been studied computationally and in vitro by ultraviolet-visible, nuclear magnetic resonance and vibrational spectroscopic techniques. Time dependant density functional theory calculations have been employed to specify various electronic transitions in ultraviolet-visible spectra. Observed chemical shifts and vibrational bands in nuclear magnetic resonance and vibrational spectra, respectively have been assigned with the help of calculations. Changes in the structure of ascorbic acid in aqueous phase have been examined computationally and experimentally by recording Raman spectra in aqueous medium. Theoretical calculations of the interaction between ascorbic acid molecule and hydroxyl radical predicted the formation of dehydroascorbic acid as first product, which has been confirmed by comparing its simulated spectra with the corresponding spectra of ascorbic acid in presence of hydrogen peroxide.
Collapse
Affiliation(s)
- Gurpreet Singh
- Department of Physics, Panjab University, Chandigarh 160 014, India
| | - B P Mohanty
- Department of Biophysics, Panjab University, Chandigarh 160 014, India
| | - G S S Saini
- Department of Physics, Panjab University, Chandigarh 160 014, India.
| |
Collapse
|
47
|
Lin XH, Lee SN, Zhang W, Li SFY. Photocatalytic degradation of terephthalic acid on sulfated titania particles and identification of fluorescent intermediates. J Hazard Mater 2016; 303:64-75. [PMID: 26513565 DOI: 10.1016/j.jhazmat.2015.10.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Revised: 09/29/2015] [Accepted: 10/12/2015] [Indexed: 06/05/2023]
Abstract
Terephthalic acid (TA) is toxic and known as an endocrine disruptor. In this paper, the photocatalytic degradation of TA using sulfated titanium dioxide SO4(2-)/TiO2 photocatalysts was investigated. The photocatalysts were prepared by sol-gel method and characterized by XRD, SEM, BET, ICP/MS and spectroscopic methods. Their activities were compared with bare TiO2 and Degussa P25. The effects of catalyst sulfur content, the initial TA concentration and pre-treatment conditions (O2, N2 or non-pretreated) were studied. O2 functions were also explored. Since there had been no comprehensive study of fluorescent intermediates reported yet, we investigated the intermediates and discovered 5 new intermediates (4 fluorescent and 1 non-fluorescent) which were identified by gas chromatography-mass spectrometry (GC/MS) and fluorescence spectroscopy. These intermediates are complementary to the previously identified carboxylic acid intermediates and might provide new insights to the mechanism of photocatalytic degradation of TA. Since TA is widely used as a probing molecule for photocatalytically generated (·)OH radicals, the ratios of fluorescent intermediates of TA degradation may provide new clues to the photocatalytic activity and mechanism. Based on the results obtained, the possible destruction pathway of TA is also proposed.
Collapse
Affiliation(s)
- Xuan Hao Lin
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Si Ni Lee
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Wenlin Zhang
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Sam Fong Yau Li
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore; NUS Environmental Research Institute (NERI), #02-01, T-Lab Building (TL), 5A Engineering Drive 1, Singapore 117411, Singapore.
| |
Collapse
|
48
|
Zeng X, Zhang X, Wang Z. Theoretical study on the OH-initiated oxidation mechanism of polyfluorinated dibenzo-p-dioxins under the atmospheric conditions. Chemosphere 2016; 144:2036-2043. [PMID: 26580719 DOI: 10.1016/j.chemosphere.2015.10.106] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 10/23/2015] [Accepted: 10/25/2015] [Indexed: 06/05/2023]
Abstract
Density functional theory (DFT) calculations at the B3LYP/6-311++G(2df,p) level of theory have been carried out to investigate the atmospheric oxidation mechanisms of some polyfluorinated dibenzo-p-dioxins (PFDDs), initiated by OH radical. The computed results show that all OH addition reactions of PFDDs are thermodynamically spontaneous processes and the branch ratio of the PFDD-OH adducts is determined by the magnitude of the Gibbs free energies of activation (Δ(r)G(≠)) and hence rate constants (k) for addition reactions. The OH reactions with all studied PFDDs are dominated by Cγ-addition and the total rate constants for OH addition decrease with increasing the number of fluorine atom substituting at α positions. Under the atmospheric conditions, the subsequent O2 addition reactions of PFDD-OH adducts occur hardly thermodynamically and are slow kinetically. For PFDD-α(β)-OH adducts without F atom at same positions the main reaction pathway is H abstraction by O2, while PFDD-γ-OH adducts will undergo fused-ring C-O bond cleavage, affording the substituted phenoxy radicals.
Collapse
Affiliation(s)
- Xiaolan Zeng
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China; College of Chemistry and Chemical Engineering, Xinyang Normal University, Henan, Xinyang 464000, China
| | - Xiaoling Zhang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Zunyao Wang
- State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
| |
Collapse
|
49
|
Moinuddin, Ansari NA, Shahab U, Habeeb S, Ahmad S. Immuno-chemistry of hydroxyl radical modified GAD-65: A possible role in experimental and human diabetes mellitus. IUBMB Life 2015; 67:746-56. [PMID: 26362234 DOI: 10.1002/iub.1431] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 08/28/2015] [Indexed: 11/10/2022]
Abstract
The repertoire of known auto-antigens is limited to a very small proportion of all human proteins, and the reason why only some proteins become auto-antigens is unclear. The 65 kDa isoform of the enzyme glutamic acid decarboxylase (GAD-65) is a major auto-antigen in type I diabetes, and in various neurological diseases. Most patients with type I diabetes (70-80%) have auto-antibodies against GAD-65, which often appear years before clinical onset of the autoimmune diabetes. Thus, the aim of the study is to focus on the immunogenicity of GAD65 and its reactive oxygen species (ROS) conformer in STZ-induced diabetic rats and on human diabetic patients. In the present study, GAD-65 was modified by hydroxyl radical following Fenton's reaction. The modifications in the structure of the GAD-65 are supported by UV-vis and fluorescence spectral studies. Immunogenicity of both native and hydroxyl radical modified GAD-65 (ROS-GAD-65) was studied in experimental rabbits and was confirmed by inducing type I diabetes in experimental male albino rats using streptozotocin (45 mg/kg). We found that ROS-GAD-65 was a better immunogen as compared to the native GAD-65. A considerable high binding to ROS-GAD-65 was observed as compared to native GAD-65 in both the serum antibodies from diabetes animal models and as well as in the serum samples of type I diabetes. Hydrogen peroxide under the exposure of UV light produces hydroxyl radical (·OH) which is most potent oxidant, and could cause protein damage (GAD-65) to the extent of generating neo-epitopes on the molecule, thus making it immunogenic.
Collapse
Affiliation(s)
- Moinuddin
- Department of Biochemistry, Faculty of Medicine, J.N. Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, 202002, India
| | - Nadeem A Ansari
- Department of Biochemistry, Faculty of Medicine, J.N. Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, 202002, India
| | - Uzma Shahab
- Department of Biochemistry, Faculty of Medicine, J.N. Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, 202002, India.,Department of Biochemistry, King George Medical University, Lucknow, Uttar Pradesh, 226003, India
| | - Safia Habeeb
- Department of Biochemistry, Faculty of Medicine, J.N. Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, 202002, India
| | - Saheem Ahmad
- Department of Biochemistry, Faculty of Medicine, J.N. Medical College, Aligarh Muslim University, Aligarh, Uttar Pradesh, 202002, India.,Department of Bio-Sciences, Integral University, Lucknow, Uttar Pradesh, 226026, India
| |
Collapse
|
50
|
Abstract
The atmospheric oxidation mechanism of chlorobenzene (CB) initiated by the OH radicals is investigated at M06-2X/6-311++G(2df, 2p) and ROCBS-QB3 levels. The oxidation is initiated by OH addition to the ortho (∼50%), para (∼33%) and meta (∼17%) positions, forming CB-OH adducts as R2, R3, and R4; while the ipso-addition is negligible (∼0.2%). The reactions of the CB-OH adducts with the atmospheric oxygen are further investigated in detail by coupling the unimolecular reaction rate theory calculations with master-equation (RRKM-ME). The CB-OH adducts react with O2 either by irreversible H-abstraction to form chlorophenol and HO2 or by reversible additions to form CB-OH-O2 radicals, which subsequently cyclize to bicyclic radicals. RRKM-ME calculations show that the addition reactions of CB-OH and O2 at the atmospheric pressure are close to but not yet reach their high-pressure-limits. The RRKM-ME simulations predict the yields of 93%, 38%, and 74% for ortho-, meta- and para-chlorophenols from the reactions of O2 with R2, R3 and R4, being lower than their high-pressure-limit yields of 95%, 48%, an 80%, respectively. Overall, the yield of chlorophenols is determined as 72% at the atmospheric pressure.
Collapse
Affiliation(s)
- Runrun Wu
- School of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou 510640, China
| | - Sainan Wang
- School of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou 510640, China
| | - Liming Wang
- School of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou 510640, China; Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, South China University of Technology, Guangzhou 510006, China.
| |
Collapse
|