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Zhu B, Ma C, You L. Degradation Mechanisms of Six Typical Glucosidic Bonds of Disaccharides Induced by Free Radicals. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:5439-5451. [PMID: 38412221 DOI: 10.1021/acs.jafc.3c09344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
Increasing hydrogen peroxide (H2O2)-based systems have been developed to degrade various polysaccharides due to the presence of highly reactive free radicals, but published degradation mechanisms are still limited. Therefore, this study aimed to clarify the degradation mechanism of six typical glucosidic bonds from different disaccharides in an ultraviolet (UV)/H2O2 system. The results showed that the H2O2 concentration, disaccharide concentration, and radiation intensity were important factors affecting pseudo-first-order kinetic constants. Hydroxyl radical, superoxide radical, and UV alone contributed 58.37, 18.52, and 19.17% to degradation, respectively. The apparent degradation rates ranked in the order of cellobiose ≈ lactose > trehalose ≈ isomaltose > turanose > sucrose ≈ maltose. The reaction pathways were then deduced after identifying their degradation products. According to quantum chemical calculations, the cleavage of α-glycosidic bonds was more kinetically unfavorable than that of β-glycosidic bonds. Additionally, the order of apparent degradation rates depended on the energy barriers for the formation of disaccharide-based alkoxyl radicals. Moreover, energy barriers for homolytic scissions of glucosidic C1-O or C7-O sites of these alkoxyl radicals ranked in the sequence: α-(1 → 2) ≈ α-(1 → 3) < α-(1 → 4) < β-(1 → 4) < α-(1 → 6) < α-(1 → 1) glucosidic bonds. This study helps to explain the mechanisms of carbohydrate degradation by free radicals.
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Affiliation(s)
- Biyang Zhu
- School of Food Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Cong Ma
- School of Food Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Lijun You
- School of Food Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510640, China
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Zhu B, Sun-Waterhouse D, You L. Insights into the mechanisms underlying the degradation of xylooligosaccharides in UV/H 2O 2 system. Carbohydr Polym 2023; 317:121091. [PMID: 37364944 DOI: 10.1016/j.carbpol.2023.121091] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/24/2023] [Accepted: 06/02/2023] [Indexed: 06/28/2023]
Abstract
UV/H2O2 process is increasingly used to degrade carbohydrates, though the underlying mechanisms remain unclear. This study aimed to fill this knowledge gap, focusing on mechanisms and energy consumption involved in hydroxyl radical (•OH)-mediated degradation of xylooligosaccharides (XOSs) in UV/H2O2 system. Results showed that UV photolysis of H2O2 generated large amounts of •OH radicals, and degradation kinetics of XOSs fitted with a pseudo-first-order model. Xylobiose (X2) and xylotriose (X3), main oligomers in XOSs, were attacked easier by •OH radicals. Their hydroxyl groups were largely converted to carbonyl groups and then carboxy groups. The cleavage rate of glucosidic bonds was slightly higher than that of pyranose ring, and exo-site glucosidic bonds were more easily cleaved than endo-site bonds. The terminal hydroxyl groups of xylitol were more efficiently oxidized than other hydroxyl groups of it, causing an initial accumulation of xylose. Oxidation products from xylitol and xylose included ketoses, aldoses, hydroxy acids and aldonic acids, indicating the complexity of •OH radical-induced XOSs degradation. Quantum chemistry calculations revealed 18 energetically viable reaction mechanisms, with the conversion of hydroxy-alkoxyl radicals to hydroxy acids being the most energetically favorable (energy barriers <0.90 kcal/mol). This study will provide more understanding of •OH radicals-mediated degradation of carbohydrates.
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Affiliation(s)
- Biyang Zhu
- School of Food Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510640, China; Research Institute for Food Nutrition and Human Health (111 Center), Guangzhou, Guangdong 510640, China
| | - Dongxiao Sun-Waterhouse
- School of Food Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510640, China; School of Chemical Sciences, University of Auckland, Auckland 1142, New Zealand
| | - Lijun You
- School of Food Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510640, China; Research Institute for Food Nutrition and Human Health (111 Center), Guangzhou, Guangdong 510640, China.
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Xu J, Guo Y, Yang Q, Bai X, Lu R, Liu M, Kuang Z, Zhang L, Li J. Enhanced cyanogen chloride formation after UV/PS and UV/H 2O 2 pre-oxidation and chlorination in natural river water. J Environ Sci (China) 2023; 126:48-57. [PMID: 36503774 DOI: 10.1016/j.jes.2022.03.049] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/29/2022] [Accepted: 03/29/2022] [Indexed: 06/17/2023]
Abstract
Ultraviolet/persulfate (UV/PS) and Ultraviolet/hydrogen peroxide (UV/H2O2) have attracted much attention in recent years as advanced oxidation processes for water treatment. However, it is not all clear how these two methods affect the formation of cyanogen chloride (CNCl) in the subsequent water chlorination process. In this study, it was found that both UV/H2O2 and UV/PS pre-oxidation promoted the formation of CNCl in six actual water samples collected from urban rivers. Glycine, uric acid, arginine and histidine were investigated as the model compounds to explore the effects of different methods on the production of CNCl. The results showed that compared with chlorination alone, pre-oxidation by UV/H2O2 and UV/PS can reduce the production of CNCl for glycine and uric acid by up to 95% during post-chlorination process. However, they can greatly promote the formation of CNCl for arginine and histidine by up to 120-fold. In a more detailed investigation, pre-oxidation of histidine formed highly reactive intermediates to chlorine, leading to increased CNCl formation and chlorine consumption. The results showed that the precursors of CNCl was altered after pre-oxidation, and need to be re-evaluated.
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Affiliation(s)
- Jie Xu
- Department of Chemistry, China Agricultural University, Beijing 100193, China
| | - Yang Guo
- Department of Chemistry, China Agricultural University, Beijing 100193, China
| | - Qian Yang
- Department of Chemistry, China Agricultural University, Beijing 100193, China
| | - Xueling Bai
- Department of Chemistry, China Agricultural University, Beijing 100193, China
| | - Runhua Lu
- Department of Chemistry, China Agricultural University, Beijing 100193, China
| | - Menghui Liu
- Department of Chemistry, China Agricultural University, Beijing 100193, China
| | - Zichen Kuang
- Department of Chemistry, China Agricultural University, Beijing 100193, China
| | - Luo Zhang
- Institute of Geographical Sciences, Henan Academy of Sciences, Zhengzhou 450052, China
| | - Jing Li
- Department of Chemistry, China Agricultural University, Beijing 100193, China.
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Zhu B, Chen Y, Chang S, Qiu H, You L. Degradation kinetic models and mechanism of isomaltooligosaccharides by hydroxyl radicals in UV/H2O2 system. Carbohydr Polym 2023; 300:120240. [DOI: 10.1016/j.carbpol.2022.120240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 10/09/2022] [Accepted: 10/14/2022] [Indexed: 11/02/2022]
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Jia S, Pu G, Xiong W, Wang P, Gao J, Yuan C. Investigation on Simultaneous Removal of SO2 and NO over a Cu–Fe/TiO2 Catalyst Using Vaporized H2O2: An Analysis on SO2 Effect. Ind Eng Chem Res 2021. [DOI: 10.1021/acs.iecr.1c01012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Shuaihui Jia
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education, Chongqing University, Chongqing 400044, P. R. China
- School of Energy and Power Engineering, Chongqing University, Chongqing 400044, P. R. China
| | - Ge Pu
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education, Chongqing University, Chongqing 400044, P. R. China
- School of Energy and Power Engineering, Chongqing University, Chongqing 400044, P. R. China
| | - Weicheng Xiong
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education, Chongqing University, Chongqing 400044, P. R. China
- School of Energy and Power Engineering, Chongqing University, Chongqing 400044, P. R. China
| | - Pengcheng Wang
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education, Chongqing University, Chongqing 400044, P. R. China
- School of Energy and Power Engineering, Chongqing University, Chongqing 400044, P. R. China
| | - Jie Gao
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education, Chongqing University, Chongqing 400044, P. R. China
- School of Energy and Power Engineering, Chongqing University, Chongqing 400044, P. R. China
| | - Cong Yuan
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education, Chongqing University, Chongqing 400044, P. R. China
- School of Energy and Power Engineering, Chongqing University, Chongqing 400044, P. R. China
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Liu Z, Liu D, Jin J, Feng L, Ni M, Zhao B, Wu X. Impact of gas impurities on the Hg 0 oxidation on high iron and calcium coal ash for chemical looping combustion. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:46130-46146. [PMID: 33410014 DOI: 10.1007/s11356-020-11872-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 11/29/2020] [Indexed: 06/12/2023]
Abstract
Coal-based mercury pollution from power plants has received increasing attention. In a previous study, high iron and calcium coal ash (HICCA) was found as a promising oxygen carrier (OC) for chemical looping combustion (CLC). The purpose of this study was to investigate the catalytic effect of HICCA on Hg0 removal as well as the impacts of several gas impurities, such as HCl, SO2, and NO. Experiments on Hg0 removal efficiencies for different atmospheres were performed in the fixed-bed reactor at 850 °C. Based upon the characterization of BET, SEM, XRD, XPS, and EDS of reaction products, the reaction mechanisms of different gases with the HICCA samples were established. The mechanisms were further explained using the thermodynamic equilibrium calculations. The experimental results showed that the Hg0 removal efficiency using HICCA was 11.60%, while the corresponding value in the presence of 50 ppm HCl was 90.46%. Hg0 removal by HICCA involving HCl is mainly attributed to homogeneous reaction between Hg0 and HCl as well as the formation of reactive species (Cl, Cl2, Cl2O, O, S, and SCl2) through the reactions of HCl with Fe2O3 and CaSO4 in HICCA. The formation of C-Cl bond is not the main pathway for the promotional effect of HCl on Hg0 removal. SO2 played a negative role in Hg0 removal by HICCA. The inhibition of SO2 may be attributed to its effect on the reduction of Fe2O3 and its bonding with C-O, COOH, and C(O)-O-C. NO enhanced Hg0 removal by HICCA primarily through the homogeneous reactions of Hg0 with N2O and O. In addition, NO also interacted with HICCA and promoted the heterogeneous oxidation of Hg0 by producing more C-O, C=O, and COOH/C(O)-O-C on HICCA surface. This study proved the effectiveness of HICCA on Hg0 removal in iG-CLC and revealed the mechanisms of the interaction between HCl/SO2/NO and MxOy/CaSO4 as well as carbon-oxygen groups.
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Affiliation(s)
- Zhuang Liu
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, China
- Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, University of Shanghai for Science and Technology, Shanghai, China
| | - Dunyu Liu
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, China.
- Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, University of Shanghai for Science and Technology, Shanghai, China.
| | - Jing Jin
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, China
- Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, University of Shanghai for Science and Technology, Shanghai, China
| | - Liang Feng
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, China
- Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, University of Shanghai for Science and Technology, Shanghai, China
| | - Mingguo Ni
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, China
- Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, University of Shanghai for Science and Technology, Shanghai, China
| | - Bingtao Zhao
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, China
- Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, University of Shanghai for Science and Technology, Shanghai, China
| | - Xiaojiang Wu
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai, China
- R&D Division, Shanghai Boiler Works Co. Ltd., Minhang, Shanghai, 200245, China
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Wang B, Yang F, Song Z, Sun L. Removal of Hg 0, NO, and SO 2 by the surface dielectric barrier discharge coupled with Mn/Ce/Ti-based catalyst. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:17648-17658. [PMID: 33403635 DOI: 10.1007/s11356-020-11886-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 11/30/2020] [Indexed: 06/12/2023]
Abstract
In this study, power parameters (power, frequency, and voltage), initial Hg0 concentration, and residence time are investigated for the removal of the increased Hg0 concentration via surface dielectric barrier discharge (SDBD). The synergistic effect of a Mn/Ce/Ti catalyst with SDBD is verified with a mixture of flue gas (Hg0, NO, and SO2). Results show that Hg0 oxidation efficiency has an optimal frequency, which declines as the input voltage increases. The amplification of the Hg0 removal efficiency decreases as voltage increases. The effect of the initial Hg0 concentration gradually decreases as the peak voltage increases. The residence time slightly affects the Hg0 removal efficiency at a high peak voltage. The cooling water temperature behaves differently on Hg0 oxidation under high and low voltages. X-ray photoelectron spectroscopy (XPS) reveals the relative atomic concentrations of Mn2+ and Mn3+ in the Mn-TiO2 and Mn-Ce-TiO2 catalysts are 66.84% and 65.80%, respectively, which indicate that Ce addition will not affect surface Mn. Mn has a limited catalytic action on the removal of flue gas with and without SDBD. Nevertheless, SDBD can stimulate the oxygen storage capacity of Mn to increase the NO2 conversion rate. Mn-Ce-TiO2 greatly improves the removal efficiencies of NO and SO2 because of the existence of the redox pairs of Mn4+/Mn3+, Ce4+/Ce3+, and Ti4+/Ti3+. However, the three catalysts slightly differ on Hg0 removal when combined with SDBD, indicating that the effect of the catalyst was weakened after SDBD was added.
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Affiliation(s)
- Ben Wang
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Fan Yang
- China-EU Institute for Clean and Renewable Energy, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Zijian Song
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Lushi Sun
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
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Song Z, Wang B, Yang W, Chen T, Li W, Ma C, Sun L. Research on NO and SO 2 removal using TiO 2-supported iron catalyst with vaporized H 2O 2 in a catalytic oxidation combined with absorption process. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:18329-18344. [PMID: 32185732 DOI: 10.1007/s11356-020-08042-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 02/10/2020] [Indexed: 06/10/2023]
Abstract
Simultaneous removal of NOx and SO2 is carried out by an oxidation-absorption process, which NO oxidized by active hydroxyl radicals (·OH) derived from catalytic decomposition of vaporized H2O2 over Fe3O4/TiO2 and then adsorbed by NaOH solution along with SO2. Fe3O4/TiO2 synthesized by wet impregnation method with an additional reduction under H2 atmosphere was characterized by XRD, FTIR, BET, XPS, and VSM analysis. Effects of H2O2 concentration, H2O2 injection rate, reaction temperature, gas flow rate, and flue gas component on simultaneous removal were investigated. The experimental results show that NO can be effectively oxidized by highly reactive ·OH radicals generated from H2O2 decomposition over Fe3O4/TiO2 catalyst, and removal efficiencies of 93.31% for NO, 85.90% for NOx, and 100% for SO2 were obtained. The surface zero-valent iron (Fe0) and divalent iron (Fe2+) are the key factors of the catalytic oxidation with hydroxyl radical. H2O2 adsorption and dissociation mechanism on catalyst surface was studied using DFT calculation. The calculation results demonstrate that H2O2 prefers to dissociate on iron containing surface, and ·OH radicals generation follow by Haber-Weiss (H-W) mechanism. The stable oxidative product of HNO2 and HNO3 were generated through NO/NO2 and H2O2 co-adsorption on the FeO/TiO2 (0 0 1) surface.
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Affiliation(s)
- Zijian Song
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Ben Wang
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
| | - Wu Yang
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Tao Chen
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Wei Li
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Chuan Ma
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Lushi Sun
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
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Yuan B, Mao X, Wang Z, Hao R, Zhao Y. Radical-induced oxidation removal of multi-air-pollutant: A critical review. JOURNAL OF HAZARDOUS MATERIALS 2020; 383:121162. [PMID: 31520933 DOI: 10.1016/j.jhazmat.2019.121162] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/14/2019] [Accepted: 09/04/2019] [Indexed: 05/21/2023]
Abstract
Sulfur dioxide (SO2), nitric oxide (NO) and elemental mercury (Hg0) are three common air pollutants in flue gas. SO2 and NO are the main precursors for chemical smog and Hg0 is a bio-toxicant for human. Cooperative removal of multi-air-pollutant in flue gas using radical-induced oxidation reaction is considered as one of the most promising methods due to the high removal efficiency, low cost and less secondary environmental impact. The common radicals used in air pollution control can be classified into four types: (1) hydroxyl radical (OH), (2) sulfate radical (SO4-), (3) chlorine-containing radicals (Cl, ClO2, ClO, HOCl-, etc.) and (4) ozone. This review summarizes the generation methods and mechanism of the four kinds of radicals, as well as their applications in the removal of multi-air-pollutant in flue gas. The reactivity, selectivity and reaction mechanism of the four kinds of radicals in multi-air-pollutant removal were comprehensively described. Finally, some future research suggestions on the development of new technique for cooperative removal of multi-air-pollutant in flue gas were provided.
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Affiliation(s)
- Bo Yuan
- Hebei Key Lab of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding, 071003, PR China; MOE Key Laboratory of Resources and Environmental Systems Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing, 102206, PR China
| | - Xingzhou Mao
- Hebei Key Lab of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding, 071003, PR China; MOE Key Laboratory of Resources and Environmental Systems Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing, 102206, PR China
| | - Zheng Wang
- Hebei Key Lab of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding, 071003, PR China
| | - Runlong Hao
- Hebei Key Lab of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding, 071003, PR China; MOE Key Laboratory of Resources and Environmental Systems Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing, 102206, PR China.
| | - Yi Zhao
- Hebei Key Lab of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding, 071003, PR China; MOE Key Laboratory of Resources and Environmental Systems Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing, 102206, PR China.
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Wei J, Gu J, Guo J, Li W, Wang C, Zhang J. Simultaneous removal of nitrogen oxides and sulfur dioxide using ultrasonically atomized hydrogen peroxide. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:22351-22361. [PMID: 31154651 DOI: 10.1007/s11356-019-05531-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 05/21/2019] [Indexed: 05/24/2023]
Abstract
A new method was developed for denitrification and desulfurization using hydrogen peroxide with the aid of an ultrasonic nebulizer to obtain high removal efficiency of NOx and SO2. Comparing with the atomizing nozzles having the aperture size of 0.01~0.02 mm, the droplets generated using the ultrasonic nebulizer show the smallest d50 value of 7.2 μm, with 72% possessing the size less than 10 μm. Based on the numerical simulation of the vaporization rate of droplets, it is indicated that the droplets with the size of 7.2 μm can be vaporized totally at very short residence time (0.11 s) under 130 °C. Effects of influence factors including the reaction temperature, the initial H2O2 concentration, pH value, and the flue gas flow rate were studied on the removal efficiencies of NO and SO2. Using the in-series double-oxidation subsystems with H2O2 concentration of 6 wt%, pH 5.0, and the reaction temperature of 130 °C, the removal efficiencies of SO2 and NO are respectively 100% and 89.3% at the short residence time of 1.8 s, and the removal efficiency of NO can be increased to 100% as the residence time is longer than 3.7 s. It is confirmed that the ultrasonically atomized H2O2 can indeed enhance the removal efficiencies of NO and SO2 at the optimal temperature, owing to the fast vaporization rate of fine droplets as well as the formation of more active radicals to be captured by NO and SO2 simultaneously. The results here provide a promising route to remove effectively the emissions of NO and SO2 simultaneously. Graphical abstract.
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Affiliation(s)
- Jiaqi Wei
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China
| | - Junjie Gu
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China
| | - Junheng Guo
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China
| | - Wei Li
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China
| | - Chenglong Wang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China
| | - Jinli Zhang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, People's Republic of China.
- School of Chemistry and Chemical Engineering, Shihezi University, Shihezi, 832003, People's Republic of China.
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