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Chen JP, Song C, Jin T, Xu J, Yang LM. Synergistic effect on simultaneous treatment of Cr(VI) and chloramphenicol using a non-thermal plasma technology. CHEMOSPHERE 2024; 359:142304. [PMID: 38734253 DOI: 10.1016/j.chemosphere.2024.142304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 05/05/2024] [Accepted: 05/09/2024] [Indexed: 05/13/2024]
Abstract
Toxic organic and heavy metal contaminants commonly exist in industrial waste stream(s) and treatment is of great challenge. In this study, a dielectric barrier discharge (DBD) non-thermal plasma technology was employed for the simultaneous treatment of two important contaminants, chloramphenicol (CAP) and Cr(VI) in an aqueous solution through redox transformations. More than 70% of CAP and 20% of TOC were degraded in 60 min, while Cr(VI) was completely removed in 10 min. The hydroxyl radicals were the main active species for the degradation. Meanwhile, the consumption of hydroxyl radicals was beneficial to the reduction of Cr(VI). The synergistic effect was investigated between CAP degradation and Cr(VI) reduction. The reduction of Cr(VI) would be enhanced in the presence of CAP with a low concentration and could be inhibited under a high concentration, because part of hydroxyl radicals could be consumed by the low-concentration CAP and the obtained intermediates with a higher kinetic rate. However, CAP with a high concentration could react with such reductive species as eaq- and •H, which could compete with Cr(VI) and inhibit the reduction. In addition, the presence of Cr(VI) enhanced the degradation and mineralization of CAP; the study of obtained intermediates indicated that the presence of Cr(VI) changed the degradation path of CAP as Cr(VI) would react with reductive species, enhance the generation of hydroxyl radicals, and cause more hydroxylation reactions. Moreover, the mechanism for the simultaneous redox transformations of CAP and Cr(VI) was illustrated. This study indicates that the DBD non-thermal plasma technology can be one of better solutions for simultaneous elimination of heavy metal and organic contaminants in aquatic environments.
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Affiliation(s)
- J Paul Chen
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518055, China; Department of Civil and Environmental Engineering, National University of Singapore, 10 Kent Ridge, Singapore.
| | - Chao Song
- Department of Civil and Environmental Engineering, National University of Singapore, 10 Kent Ridge, Singapore
| | - Tenghui Jin
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518055, China
| | - Jiajie Xu
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518055, China
| | - Li-Ming Yang
- Department of Chemical and Biochemical Engineering, National University of Singapore, 10 Kent Ridge, Singapore
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Sun W, Xu N, Jiang W, Cheng G. Mechanistic insights into manganese oxide impacting the oxidation and transport of Cr(III) immobilized by nano-zero valent charged ion particles in water-saturated porous media. JOURNAL OF HAZARDOUS MATERIALS 2024; 469:134050. [PMID: 38493629 DOI: 10.1016/j.jhazmat.2024.134050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 03/10/2024] [Accepted: 03/14/2024] [Indexed: 03/19/2024]
Abstract
The presence of manganese oxide (MnO2) could influence the stability of green-synthesized nano-zero valent iron (nZVI@GT) associated with trivalent chromium (Cr(III)) after its excess application in the in situ remediation of hexachromium (Cr(VI)) contaminated soil. The research findings revealed that the co-transport of the remaining nZVI@GT with Cr(III) was substantially inhibited by high δ-MnO2 concentrations due to the formation of hetero-aggregates between nZVI@GT and δ-MnO2, resulting in an increased irreversible attachment parameter at second-site in a two-site kinetic attachment model. Simultaneously, the Cr(III) complex immobilized on nZVI@GT could be oxidized leading to high levels of Cr(VI) leaching at high δ-MnO2 concentrations. During this process, Mn(IV) was converted to Mn(III)/Mn(II). Subsequently, leachate containing a partial amount of Cr(VI) preferentially adsorbed onto the nZVI@GT surface, enhancing the dispersion of the nZVI@GT and δ-MnO2 agglomerates. Thereafter, nZVI@GT transportability was enhanced with a decreased second-site attachment parameter and the flow content of dissolved Cr(VI) was increased to double, also increasing the potential risk of Cr(VI) being carried by nZVI@GT to underground water systems. This study provides theoretical support for preserving the long-term stability of nZVI@GT after the in situ remediation of heavy metal-contaminated sites in the presence of δ-MnO2.
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Affiliation(s)
- Wu Sun
- School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China
| | - Nan Xu
- School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China; Jiangsu Key Laboratory of Environmental Functional Materials, Suzhou University of Science and Technology, Suzhou 215009, China.
| | - Wenxin Jiang
- School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China
| | - Gongbi Cheng
- Jiangsu Gaiya Environmental S&T Corp, Suzhou 215000, China
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Shu Z, Liu Q, Liu E, Pan Z, Yan S, Zhang L, Song W, Wang Z. Overlooked role of aqueous chromate (VI) as a photosensitizer in enhancing the photochemical reactivity of ferrihydrite and production of hydroxyl radical. JOURNAL OF HAZARDOUS MATERIALS 2024; 466:133557. [PMID: 38309168 DOI: 10.1016/j.jhazmat.2024.133557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/26/2023] [Accepted: 01/16/2024] [Indexed: 02/05/2024]
Abstract
The reactive oxygen species (ROS) photochemically generated from natural iron minerals have gained significant attention. Amidst the previous studies on the impact of heavy metal ions on ROS generation, our study addresses the role of the anion Cr(VI), with its intrinsic photoactivity, in influencing ROS photochemical generation with the co-presence of minerals. We investigated the transformation of inorganic/organic pollutants (Cr(VI) and benzoic acid) at the ferrihydrite interface, considering sunlight-mediated conversion processes (300-1000 nm). Increased photochemical reactivity of ferrihydrite was observed in the presence of aqueous Cr(VI), acting as a photosensitizer. Meanwhile, a positive correlation between hydroxyl radical (•OH) production and concentrations of aqueous Cr(VI) was observed, with a 650% increase of •OH generation at 50 mg L-1 Cr(VI) compared to systems without Cr(VI). Our photochemical batch experiments elucidated three potential pathways for •OH photochemical production under varying wet chemistry conditions: (1) ferrihydrite hole-mediated pathway, (2) chromium intermediate O-I-mediated pathway, and (3) chromium intermediates CrIV/V-mediated pathway. Notably, even in the visible region (> 425 nm), the promotion of aqueous Cr(VI) on •OH accumulation was observed in the presence of ferrihydrite and TiO2 suspensions, attributed to Cr(VI) photosensitization at the mineral interface. This study sheds light on the overlooked role of aqueous Cr(VI) in the photochemical reactivity of minerals, thereby enhancing our understanding of pollutant fate in acid mining-impacted environments.
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Affiliation(s)
- Zhipeng Shu
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
| | - Qiuyao Liu
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
| | - Enyang Liu
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
| | - Zezhen Pan
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China; National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Institute of Eco-Chongming, Fudan University, Shanghai 200062, China.
| | - Shuwen Yan
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
| | - Liwu Zhang
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
| | - Weihua Song
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
| | - Zimeng Wang
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China; National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Institute of Eco-Chongming, Fudan University, Shanghai 200062, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
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Yang T, Huang C, An L, Zeng G, Li J, Liu C, Xu X, Jia J, Ma J. The overlooked role of Cr(VI) in micropollutant degradation under solar light irradiation. WATER RESEARCH 2023; 242:120309. [PMID: 37451190 DOI: 10.1016/j.watres.2023.120309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 06/30/2023] [Accepted: 07/03/2023] [Indexed: 07/18/2023]
Abstract
Hexavalent chromium (Cr(VI)) is ubiquitous in natural environments, whereas its role in the transformation of coexisting contaminants may have been overlooked. In this work, it was reported for the first time that the irradiation of Cr(VI) by solar light (solar light/Cr(VI) system) could effectively degrade various micropollutants with different structures. The removal efficiency of selected micropollutants was increased by 13.3-64.8% by the solar light/Cr(VI) system compared to that by direct solar photolysis. Meanwhile, the oxidation rates were enhanced by 2.2-21.5 folds, while they were negligible by Cr(VI) oxidation alone. Experiments by specific scavengers, probe compounds, fluorescence absorbance, and electron spin resonance analysis demonstrated that hydroxyl radical (•OH) was the major reactive species in the solar light/Cr(VI) system. Further experiments showed that the generation of •OH was closely related to the intermediate Cr(V) generated from Cr(VI) reduction, and Cr(V) could be re-oxidized back to Cr(VI). Increasing solution pH negatively affected model micropollutant (carbamazepine (CBZ)) degradation by the solar light/Cr(VI) system, mainly due to the decreased quantum yield of •OH at higher pH. Coexisting sulfate ions showed negligible effect on CBZ degradation in the solar light/Cr(VI) system, while the presence of bicarbonate, chloride, and humic acid inhibited CBZ degradation to varying degrees, owing to their diverse scavenging effects on •OH. Furthermore, moderate CBZ degradation was also achieved by natural solar light photolysis of Cr(VI). This study demonstrated the pivotal role of Cr(VI) in the transformation of micropollutants under solar irradiation, which advances the understanding of the fate of micropollutants in natural environments.
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Affiliation(s)
- Tao Yang
- School of Biotechnology and Health Science, Wuyi University, Jiangmen, Guangdong Province 529020, PR China.
| | - Cui Huang
- School of Biotechnology and Health Science, Wuyi University, Jiangmen, Guangdong Province 529020, PR China
| | - Linqian An
- School of Biotechnology and Health Science, Wuyi University, Jiangmen, Guangdong Province 529020, PR China
| | - Ge Zeng
- School of Biotechnology and Health Science, Wuyi University, Jiangmen, Guangdong Province 529020, PR China
| | - Juan Li
- Advanced Interdisciplinary Institute of Environment and Ecology, Beijing Normal University, Zhu Hai 519087, PR China.
| | - Changyu Liu
- School of Biotechnology and Health Science, Wuyi University, Jiangmen, Guangdong Province 529020, PR China
| | - Xiaolong Xu
- School of Biotechnology and Health Science, Wuyi University, Jiangmen, Guangdong Province 529020, PR China
| | - Jianbo Jia
- School of Biotechnology and Health Science, Wuyi University, Jiangmen, Guangdong Province 529020, PR China
| | - Jun Ma
- State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, PR China
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