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Xue S, Miao Z, Gao M, Wan K. Structural analysis of lignite-derived humic acid and its microscopic interactions with heavy metal ions in aqueous solution. Sci Total Environ 2023; 897:165385. [PMID: 37423290 DOI: 10.1016/j.scitotenv.2023.165385] [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: 01/27/2023] [Revised: 06/01/2023] [Accepted: 07/06/2023] [Indexed: 07/11/2023]
Abstract
Understanding heavy metal environmental behavior with humic acid (HA) is critical. There is currently a lack of information on the control of its structure organization on its reactivity to metals. The difference in HA structures under non-homogeneous conditions is critical for revealing its micro-interaction with heavy metals. The heterogeneity of HA was reduced using the fractionation method in this study, the chemical properties of HA fractions were analyzed using py-GC/MS, and the structural units of HA were proposed. Pb2+ was used as a probe to investigate the difference in the adsorption capacity of HA fractions. The microscopic interaction of structures with heavy metal was investigated and validated by structural units. The results show that as molecular weight increased, the oxygen content and the number of aliphatic chains decreased, but the opposite was true for aromatic and heterocyclic rings. The adsorption capacity for Pb2+ was as follows: HA-1 > HA-2 > HA-3. According to the linear analysis of the influencing factors of maximum adsorption capacity and possibility factors, the adsorption capacity was positively correlated with the contents of acid groups, carboxyl groups, phenolic hydroxyl groups, and the number of aliphatic chains. The phenolic hydroxyl group and the aliphatic-chain structure have the greatest impact. Therefore, structural differences and the number of active sites play an important role in adsorption. The binding energy of HA structural units to Pb2+ was calculated. It was found that the chain structure is easier to bind to heavy metals than aromatic rings, and the affinity of-COOH to Pb2+ is greater than that of -OH. These findings can help improve the adsorbent design.
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Affiliation(s)
- Shuwen Xue
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
| | - Zhenyong Miao
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
| | - Mingqiang Gao
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China
| | - Keji Wan
- National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou, 221116, Jiangsu, China.
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Zhang Z, Liu S, Wang X, Huang S, Sun K, Xia X. Differences in structure and composition of soil humic substances and their binding for polycyclic aromatic hydrocarbons in different climatic zones. Environ Pollut 2023; 322:121121. [PMID: 36681379 DOI: 10.1016/j.envpol.2023.121121] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [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: 10/05/2022] [Revised: 01/13/2023] [Accepted: 01/17/2023] [Indexed: 06/17/2023]
Abstract
Humic substances (HSs) play important roles in the transport and bioavailability of hydrophobic organic compounds (HOCs) in soils. The sorption of HOCs depends on the compositions and structures of HSs which may differ in different climatic zones, however, the sorption behavior of HOCs by HSs in soils from different climatic zones is poorly understood. In this study, different HS fractions (humic acids-HAs, fulvic acids-FAs and humin-HM) in soils from different climatic zones were extracted and used as sorbents for polycyclic aromatic hydrocarbons (PAHs). The results indicated that HSs (including HA, FA and HM fractions) from colder climatic zones contained more oxygen-containing functional groups and exhibited smaller molecular weight as well as higher aliphaticity and polarity than those from warmer climatic zones. The sorption affinity of HAs at the low given concentration (0.05 Sw) of naphthalene (Nap), phenanthrene (Phe), pyrene (Pyr) and benz(α)anthracene (BaA) from warmer climatic zones to colder ones increased from 26.3 to 43.9, from 36.7 to 114.0, from 125.8 to 388.8, and from 322.5 to 876.1, respectively, and the same trends were obtained for FAs and HM at the same PAH concentration. The results indicated that HSs from colder climatic zones showed higher sorption affinity than those from warmer climatic zones. Moreover, the weighted contributions of FAs, HAs and HM to the overall sorption from different climatic zones were 9.1-28.4%, 13.5-59.2% and 23.4-76.9%, respectively. This indicates FA fraction, a previously neglected component, is also an important contributor to binding PAHs in soils. This study suggests that the difference in sorption behaviors of HOCs to HSs among different climatic zones should be considered when predicting HOC fates and bioavailability in soils.
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Affiliation(s)
- Zhenrui Zhang
- Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
| | - Shaoda Liu
- Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
| | - Xilong Wang
- Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Shurui Huang
- Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
| | - Ke Sun
- Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
| | - Xinghui Xia
- Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China
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Wan K, Wang G, Bo W, Xue S, Miao Z. A Sandwich Structure of Fulvic Acid and PMIDA-Modified LDHs for the Simultaneous Removal of Cu 2+ and Aniline in Multicomponent Solutions. Langmuir 2023; 39:2537-2547. [PMID: 36758167 DOI: 10.1021/acs.langmuir.2c02724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The coexistence of organic and inorganic pollutants in industrial wastewater has emerged as a concerning environmental issue worldwide due to the critical levels of biological toxicity of these pollutants. In this context, the present study proposes a sandwich structure of fulvic acid and PMIDA-modified LDHs (FA/PMIDA-LDHs) for the simultaneous removal of Cu2+ and aniline from wastewater. The specific structure was synthesized using a combination of coprecipitation and impregnation methods. Abundant benzene rings and oxygen-containing functional groups greatly increased the number of sites for the adsorption of both Cu2+ and aniline. The maximum adsorption capacity of Cu2+ and aniline in solution with initial pH 5.0 at 25 °C could reach 221.24 and 132.28 mg/g, respectively. Cu2+ could be chelated by the functional groups in the FA/PMIDA-LDHs structure, and a coupled reduction-complexation mechanism was proposed for this process. The uptake of aniline on FA/PMIDA-LDHs was demonstrated to be a result of the combination of coordination forces, hydrophobic effects, π-π interactions, and hydrogen bonds. In a multicomponent solution, FA/PMIDA-LDHs exhibited excellent salt tolerance of up to 1000 mg/L of Na+ or Ca2+. The effects of Fe3+, Ni2+, Cl-, Cr2O72-, SO42-, and H2PO4- on the uptakes of Cu2+ and aniline were also investigated.
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Affiliation(s)
- Keji Wan
- National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
| | - Guoqiang Wang
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
| | - Wenting Bo
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
| | - Shuwen Xue
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
| | - Zhenyong Miao
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
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Song C, Sun S, Wang J, Gao Y, Yu G, Li Y, Liu Z, Zhang W, Zhou L. Applying fulvic acid for sediment metals remediation: Mechanism, factors, and prospect. Front Microbiol 2023; 13:1084097. [PMID: 36699598 PMCID: PMC9868176 DOI: 10.3389/fmicb.2022.1084097] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 12/19/2022] [Indexed: 01/11/2023] Open
Abstract
Fulvic acid (FA) has been shown to play a decisive role in controlling the environmental geochemical behavior of metals. As a green and natural microbial metabolite, FA is widely used in environmental remediation because of its good adsorption complexation and redox ability. This paper introduces the reaction mechanism and properties of FA with metals, and reviews the progress of research on the remediation of metal pollutant by FA through physicochemical remediation and bioremediation. FA can control the biotoxicity and migration ability of some metals, such as Pb, Cr, Hg, Cd, and As, through adsorption complexation and redox reactions. The concentration, molecular weight, and source are the main factors that determine the remediation ability of FA. In addition, the ambient pH, temperature, metal ion concentrations, and competing components in sediment environments have significant effects on the extent and rate of a reaction between metals and FA during the remediation process. Finally, we summarize the challenges that this promising environmental remediation tool may face. The research directions of FA in the field of metals ecological remediation are also prospected. This review can provide new ideas and directions for the research of remediation of metals contaminants in sediments.
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Affiliation(s)
- Chuxuan Song
- School of Hydraulic and Environmental Engineering, Changsha University of Science and Technology, Changsha, China
| | - Shiquan Sun
- School of Hydraulic and Environmental Engineering, Changsha University of Science and Technology, Changsha, China.,Key Laboratory of Dongting Lake Aquatic Eco-Environmental Control and Restoration of Hunan Province, Changsha, China
| | - Jinting Wang
- School of Hydraulic and Environmental Engineering, Changsha University of Science and Technology, Changsha, China
| | - Yang Gao
- School of Hydraulic and Environmental Engineering, Changsha University of Science and Technology, Changsha, China
| | - Guanlong Yu
- School of Hydraulic and Environmental Engineering, Changsha University of Science and Technology, Changsha, China
| | - Yifu Li
- School of Hydraulic and Environmental Engineering, Changsha University of Science and Technology, Changsha, China
| | - Zhengqian Liu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Zhang
- School of Hydraulic and Environmental Engineering, Changsha University of Science and Technology, Changsha, China
| | - Lean Zhou
- School of Hydraulic and Environmental Engineering, Changsha University of Science and Technology, Changsha, China
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Wang Z, Yao Y, Yang Y. Fulvic acid-like substance-Ca(II) complexes improved the utilization of calcium in rice: Chelating and absorption mechanism. Ecotoxicol Environ Saf 2022; 237:113502. [PMID: 35447470 DOI: 10.1016/j.ecoenv.2022.113502] [Citation(s) in RCA: 2] [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: 09/10/2021] [Revised: 04/05/2022] [Accepted: 04/07/2022] [Indexed: 06/14/2023]
Abstract
Water-soluble chelated calcium has been widely used in agriculture as a fertilizer to improve the absorption and utilization of calcium by plants. This paper prepared a new organic mineral fertilizer, based on fulvic acid-like substance chelated calcium (PFA-Ca2+ complex), using optimal parameters (i.e., pH, time, temperature, and Ca2+ concentration) to achieve a high chelation efficiency. The absorption, utilization, and distribution of the PFA-Ca2+ complex in rice roots were analyzed using laser scanning confocal microscopy (LSCM). Our results demonstrated that the optimal PFA-Ca2+ complex chelating efficiency (87%) was achieved at an initial Ca2+ concentration of 0.1 mol L-1, an equilibration time of 120 min, a pH of 5.0, and a temperature of 40 °C. The chelating reaction of a fulvic acid-like substance with Ca2+ primarily occurred on phenol hydroxyl, alcohol hydroxyl, and carboxyl groups. The PFA-Ca2+ complex was primarily enriched in the roots' pericycle, cortical, and epidermis cells, in both chelating and non-chelating forms. To our knowledge, this is the first report investigating how the PFA-Ca2+complex affects transformation in plants, which has significant implications for research on plant nutrition and nutrient distribution.
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Affiliation(s)
- Zhonghua Wang
- National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources; National Engineering & Technology Research Center for Slow and Controlled-Release Fertilizers, College of Resources and Environment, Shandong Agricultural University, Daizong Road No. 61, Taian, Shandong 271018, China
| | - Yuanyuan Yao
- National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources; National Engineering & Technology Research Center for Slow and Controlled-Release Fertilizers, College of Resources and Environment, Shandong Agricultural University, Daizong Road No. 61, Taian, Shandong 271018, China
| | - Yuechao Yang
- National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources; National Engineering & Technology Research Center for Slow and Controlled-Release Fertilizers, College of Resources and Environment, Shandong Agricultural University, Daizong Road No. 61, Taian, Shandong 271018, China; Department of Soil and Water Science, Tropical Research and Education Center, University of Florida, Homestead, FL 33031, United States.
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Lu X, Zeng F, Wei S, Gao R, Abdurahman A, Wang H, Liang W. Effects of humic acid on Pb 2+ adsorption onto polystyrene microplastics from spectroscopic analysis and site energy distribution analysis. Sci Rep 2022; 12:8932. [PMID: 35624134 PMCID: PMC9142603 DOI: 10.1038/s41598-022-12776-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 05/16/2022] [Indexed: 12/03/2022] Open
Abstract
Microplastics (MPs), act as vectors of heavy metal pollutants in the environment, is of practical significance to study the adsorption process and mechanism on heavy metals. In this study, polystyrene microplastics (PSMPs) were used as model MPs to study the adsorption of Pb2+ on PSMPs and the effects of humic acid (HA) on the adsorption process. The results showed that HA promoted the adsorption of Pb2+ on PSMPs, and the higher the concentration of HA, the greater the adsorption of Pb2+. With the increase of pH value and decrease of ionic strength, the adsorption capacity of PSMPs for Pb2+ increased. The scanning electron microscope equipped with the energy dispersive spectroscope (SEM–EDS), fourier transform-infrared spectra (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis showed that Pb2+ could be adsorbed directly onto PSMPs and also indirectly by HA. The higher KSV values in the PSMPs-HA-Pb2+ system than PSMPs-HA system by fluorescence analysis of HA suggested that HA acted as a bridging role in the adsorption of Pb2+ on PSMPs. The site energy distribution analysis further revealed that HA increased the average site energy μ(E*) and its standard deviation σe* of PSMPs by introducing more adsorption sites, thus enhanced the adsorption affinity of PSMPs. This study provided more thoughts and insights into the adsorption behavior and mechanism of MPs for Pb2+ in aquatic environments.
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Affiliation(s)
- Xiaotian Lu
- School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Feng Zeng
- School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Shuyin Wei
- School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Rui Gao
- School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Abliz Abdurahman
- School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Hao Wang
- School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Weiqian Liang
- School of Chemistry, Sun Yat-Sen University, Guangzhou, 510275, China.
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Gao R, Wang H, Abdurahman A, Liang W, Lu X, Wei S, Zeng F. Insight into the hetero-interactions of 4-nonylphenol with dissolved organic matter: multiple spectroscopic methods, 1H NMR study and principal component analysis. RSC Adv 2022; 12:22416-22424. [PMID: 36105990 PMCID: PMC9364969 DOI: 10.1039/d2ra03739d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 08/01/2022] [Indexed: 11/30/2022] Open
Abstract
Understanding the interactions between heterogeneous dissolved organic matter (DOM) and nonylphenols (NPs) is essential for predicting their behavior and fate in the environment. Herein, we firstly obtained different MW-fractionated humic acids (HAs) using the ultrafiltration method. Afterward, the molecular weight (MW)-dependent interactions of HAs with 4-nonylphenol (4-NP) were analysed by excitation emission matrix (EEM) fluorescence spectroscopy, fluorescence quenching, UV-vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and principal component analysis (PCA). EEM spectra indicated that the quenching mechanism was static. In the binding process, the higher MW fractions showed stronger interaction with 4-NP than the lower MW counterparts, exhibiting a clear MW-dependent interaction heterogeneity. The interaction constants for the 4-NP–HAs system were suppressed as the ionic strength decreased and pH increased, which was especially obvious in the binding of 4-NP to the lower MW-fractionated HAs. The FTIR spectra revealed that hydroxyl and aromatics were involved in the interaction process of HA fractions with 4-NP. It was also found from 1H NMR that π–π interactions between aromatic rings of 4-NP and MW-fractionated HAs were responsible for the complexation. The correlation analysis and PCA results indicated that aromaticity and MW play important roles in the interaction process and confirmed an obvious interaction heterogeneity among MW-fractionated HAs samples. This work highlighted MW-dependent interaction heterogeneities of HA, which suggested that heterogeneity in MW distribution should be taken into consideration when exploring the fate and biogeochemistry cycling of 4-NP from contaminated environments. Multiple spectroscopic methods, 1H NMR study and PCA were used to investigate the heterointeractions of 4-nonylphenol with humic acids.![]()
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Affiliation(s)
- Rui Gao
- School of Chemistry, Sun Yat-sen University, Guangzhou, Guangdong, 510275, China
| | - Hao Wang
- School of Chemistry, Sun Yat-sen University, Guangzhou, Guangdong, 510275, China
| | - Abliz Abdurahman
- School of Chemistry, Sun Yat-sen University, Guangzhou, Guangdong, 510275, China
| | - Weiqian Liang
- School of Chemistry, Sun Yat-sen University, Guangzhou, Guangdong, 510275, China
| | - Xiaotian Lu
- School of Chemistry, Sun Yat-sen University, Guangzhou, Guangdong, 510275, China
| | - Shuyin Wei
- School of Chemistry, Sun Yat-sen University, Guangzhou, Guangdong, 510275, China
| | - Feng Zeng
- School of Chemistry, Sun Yat-sen University, Guangzhou, Guangdong, 510275, China
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Li Z, Gong Y, Zhao D, Dang Z, Lin Z. Evaluation of three common alkaline agents for immobilization of multi-metals in a field-contaminated acidic soil. Environ Sci Pollut Res Int 2021; 28:60765-60777. [PMID: 34165755 DOI: 10.1007/s11356-021-14670-3] [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: 03/30/2021] [Accepted: 05/27/2021] [Indexed: 06/13/2023]
Abstract
We investigated three common alkaline agents (NaOH, CaO, and Mg(OH)2) for immobilization of four heavy metals (Pb, Zn, Cu, and Cd) in a field-contaminated soil and elucidated the underpinning principles. NaOH caused the highest pH spike in the soil, while CaO and Mg(OH)2 served as a longer-lasting source of OH-. Amending the soil with CaO or Mg(OH)2 at ≥0.1 mol as OH- (kg·soil)-1 for 24 h was able to immobilize all four metals, while NaOH failed. NaOH leached up to 3 times more organic carbon than CaO and Mg(OH)2, resulting in elevated leachability of the metals. Column elution tests showed that amendments by CaO and Mg(OH)2 lowered the leachable Pb2+, Zn2+, Cu2+, and Cd2+ by 52-54%, 71-75%, 69-73%, and 68%, respectively, after 1440 pore volumes of elution. Sequential extraction revealed that the soil amendments converted the exchangeable fraction of the metals to the much less available forms. XRD and FTIR analyses indicated that formation of metal oxide precipitates and complexation with soil organic matter were responsible for the metals immobilization. Taken together the chemical cost, technical effectiveness, and environmental impact, CaO is the most suitable alkaline agent for remediation of soil contaminated with heavy metals.
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Affiliation(s)
- Zhiliang Li
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China
- Environmental Engineering Program, Department of Civil & Environmental Engineering, Auburn University, Auburn, AL, 36849, USA
| | - Yanyan Gong
- School of Environment, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou, 511443, China.
| | - Dongye Zhao
- Environmental Engineering Program, Department of Civil & Environmental Engineering, Auburn University, Auburn, AL, 36849, USA.
| | - Zhi Dang
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China
- The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou, 510006, China
| | - Zhang Lin
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China
- The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou, 510006, China
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Boguta P, Sokołowska Z. Zinc Binding to Fulvic acids: Assessing the Impact of pH, Metal Concentrations and Chemical Properties of Fulvic Acids on the Mechanism and Stability of Formed Soluble Complexes. Molecules 2020; 25:E1297. [PMID: 32178414 PMCID: PMC7144464 DOI: 10.3390/molecules25061297] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 03/06/2020] [Accepted: 03/09/2020] [Indexed: 11/17/2022] Open
Abstract
The aim of the study was defined as a complementary analysis of molecular interactions between zinc (Zn) and fulvic acids (FAs) at a broad pH range (3-7), different metal concentrations (0-50 mg dm-3) and chemical properties of FAs and their impact on the Zn binding mechanism, stability, and efficiency. The results showed that the complexation reaction prevailed at pH 6 and 7, whereas protons exchange dominated interactions at pH 3. Stability constant of the complexes increased along with pH (logK increased from ~3.8 to 4.2). Complexation was preferred by less-humidified structures of lower molecular mass containing more oxygen groups. The number of fluorophores available for Zn(II) increased from pH 3 to 7 by ~44%. Depending on the pH, complexation involved a bidentate chelate, monodentate and bidentate bridging mode. Zn(II) binding was insufficiently modeled by the classic Stern-Volmer equation and well described by the double logarithmic equation (R > 0.94) as well as by a modified Stern-Volmer formula assuming the existence of available and unavailable fluorophore populations (R > 0.98). The fluorescence ratio of different fluorophores was proposed as an indicator of the binding affinity of various structures. A positive relationship was found between the fraction of accessible fluorophores and Zn(II) binding at pH 7 determined based on proton release (R = 0.91-0.97). The obtained results can find application in controlling the mobility and bioavailability of Zn in different conditions.
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Affiliation(s)
- Patrycja Boguta
- Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland;
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Li H, Wang J, Zhao B, Gao M, Shi W, Zhou H, Xie Z, Zhou B, Lü C, He J. The role of major functional groups: Multi-evidence from the binding experiments of heavy metals on natural fulvic acids extracted from lake sediments. Ecotoxicol Environ Saf 2018; 162:514-520. [PMID: 30015198 DOI: 10.1016/j.ecoenv.2018.07.038] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [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: 03/28/2018] [Revised: 07/08/2018] [Accepted: 07/09/2018] [Indexed: 06/08/2023]
Abstract
Fulvic acid (FA) plays a key role in governing the environmental geochemistry behavior of heavy metals. In this work, the roles of major functional groups were investigated based on binding experiments of heavy metals on natural FA extracted from lake sediments. The results showed that the adsorption capacities were ranked as Cu2+ > Pb2+ >Cd2+. The differences of peak area at 3412, 1713, 617and 2430 cm-1 pre- and post-binding reactions in FTIR spectra suggested that phenolic, carboxyl and nitrogen-containing groups were the major functional groups providing sites binding heavy metals. Moreover, the results of bi-Langmuir model and the ionic strength effects jointly indicated that electrostatic attraction was the key mechanism during the adsorption process. The fitted results of Ligand-binding model suggested that the major functional groups in FA were classified into two types binding sites: weak (i.e. phenolic and carboxyl groups) and strong binding sites (i.e. nitrogen-containing groups). Additionally, there might be p-benzoquinone-like formed in FA which were then reduced to hydroquinone during the adsorption process, corresponding to the changing of peak area at 1614 and 830 cm-1 in FTIR spectra, the occurrence of Peak C in Fluorescence excitation-emission matrix (EEM) spectra and the ratios of H/C (<1) and O/C (≈1). The organic matter in sediments from Lake Wuliangsuhai presented similar characteristics with terrestrial plants due to the lake characterized by Phragmites australis and Potamogeton pectinatus L. being the dominant species, which shared large proportions of woody tissues as well as waxy hydrocarbons resembling that of terrestrial plants. This work is useful to insight the environmental effects of FA on heavy metals in environment.
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Affiliation(s)
- Hao Li
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China
| | - Jinghua Wang
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China
| | - Boyi Zhao
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China
| | - Manshu Gao
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China
| | - Wenjing Shi
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China
| | - Haijun Zhou
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China; Environmental Monitoring Center of Inner Mongolia, Hohhot 010011, China
| | - Zhilei Xie
- Environmental Monitoring Center of Inner Mongolia, Hohhot 010011, China
| | - Bin Zhou
- Tianjin Academy of Environmental Sciences, Tianjin 300191, China
| | - Changwei Lü
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China; Institute of Environmental Geology, Inner Mongolia University, Hohhot 010021, China.
| | - Jiang He
- Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China; Institute of Environmental Geology, Inner Mongolia University, Hohhot 010021, China.
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