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Niu Y, Zhang Q, Wang L, Guo F, Zhang Y, Wu J. Synthesis of Fe-N doped porous carbon/silicate composites regulated by minerals in coal gasification fine slag for synergistic electrocatalytic treatment of phenolic wastewater. ENVIRONMENTAL RESEARCH 2024; 251:118643. [PMID: 38458590 DOI: 10.1016/j.envres.2024.118643] [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: 01/01/2024] [Revised: 02/08/2024] [Accepted: 03/05/2024] [Indexed: 03/10/2024]
Abstract
Coal gasification fine slag (CGFS), as a difficult-to-dispose solid waste in the coal chemical industry, consists of minerals and residual carbon. Due to the aggregate structure of minerals blocking pores and encapsulating active substances, the high-value utilization of CGFS still remains a challenge. Based on the intrinsic characteristics of CGFS, this study synthesized Fe-N doped porous carbon/silicate composites (Fe-NC) by alkali activation and pyrolysis for electrocatalytic degradation of phenolic wastewater. Meanwhile, minerals were utilized to regulate the surface chemical and pore structure, turning their disadvantages into advantages, which caused a sharp increase in m-cresol mineralization. The positive effect of minerals on composite properties was investigated by characterization techniques, electrochemical analyses and density functional theory (DFT) calculations. It was found that the mesoporous structure of the mineral-regulated composites was further developed, with more carbon defects and reactive substances on its surface. Most importantly, silicate mediated iron conversion through strong interaction with H2O2, high work function gradient with electroactive iron, and excellent superoxide radical (•O2-) production capacity. It effectively improved the reversibility and kinetics of the entire electrocatalytic reaction. Within the Fe-NC311 electrocatalytic system, the m-cresol removal rate reached 99.55 ± 1.24%, surpassing most reported Fe-N-doped electrocatalysts. In addition, the adsorption and electrooxidation experiment confirmed that the synergistic effect of Fe-N doped porous carbon and silicate simultaneously promoted the capture of pollutants and the transformation of electroactive molecules, and hence effectively shortened the diffusion path of short-lived radicals, which was further supported by molecular dynamics simulation. Therefore, this research provides new insights into the problem of mineral limitations and opens an innovative approach for CGFS recycling and environmental remediation.
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Affiliation(s)
- Yanjie Niu
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, 221116, PR China
| | - Qiqi Zhang
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, 221116, PR China
| | - Li Wang
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, 221116, PR China
| | - Fanhui Guo
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, 221116, PR China
| | - Yixin Zhang
- Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou, 221116, PR China
| | - Jianjun Wu
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, 221116, PR China.
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Li W, Wei K, Yin X, Zhu H, Zhu Q, Zhang X, Liu S, Han W. An extra-chelator-free fenton process assisted by electrocatalytic-induced in-situ pollutant carboxylation for target refractory organic efficient treatment in chemical-industrial wastewater. ENVIRONMENTAL RESEARCH 2023:116243. [PMID: 37270077 DOI: 10.1016/j.envres.2023.116243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 05/24/2023] [Accepted: 05/25/2023] [Indexed: 06/05/2023]
Abstract
For traditional Fenton processes, the quenching behavior of radical contenders (e.g., most aliphatic hydrocarbons) on hydroxyl radicals (·OH) usually hinders the removal of target refractory pollutants (aromatic/heterocyclic hydrocarbons) in chemical industrial wastewater, leading to excess energy consumption. Herein, we proposed an electrocatalytic-assisted chelation-Fenton (EACF) process, with no extra-chelator addition, to significantly enhance target refractory pollutant (pyrazole as a representative) removal under high ·OH contender (glyoxal) levels. Experiments and theoretical calculations proved that superoxide radical (·O2-) and anodic direct electron transfer (DET) effectively converted the strong ·OH-quenching substance (glyoxal) to a weak radical competitor (oxalate) during the electrocatalytic oxidation process, promoting Fe2+ chelation and therefore increasing radical utilization for pyrazole degradation (reached maximum of ∼43-fold value upon traditional Fenton), which appeared more obviously in neutral/alkaline Fenton conditions. For actual pharmaceutical tailwater treatment, the EACF achieved 2-folds higher oriented-oxidation capability and ∼78% lower operation cost per pyrazole removal than the traditional Fenton process, demonstrating promising potential for future practical applications.
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Affiliation(s)
- Wei Li
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science & Technology, Nanjing, 210094, PR China
| | - Kajia Wei
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science & Technology, Nanjing, 210094, PR China.
| | - Xu Yin
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science & Technology, Nanjing, 210094, PR China
| | - Hongwei Zhu
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science & Technology, Nanjing, 210094, PR China
| | - Quanqi Zhu
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science & Technology, Nanjing, 210094, PR China
| | - Xiaoyuan Zhang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, PR China
| | - Siqi Liu
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science & Technology, Nanjing, 210094, PR China; Institute for Advanced Membrane Technology (IAMT), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344, Eggenstein-Leopoldshafen, Germany
| | - Weiqing Han
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science & Technology, Nanjing, 210094, PR China.
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Liu R, Wang L, Wu R, Liu S, Korshin GV, Han W. Active-chlorine-mediated oxidation of 5-fluorouracil on a hierarchically ordered macroporous RuO 2 electrode. CHEMOSPHERE 2022; 301:134728. [PMID: 35487356 DOI: 10.1016/j.chemosphere.2022.134728] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 04/19/2022] [Accepted: 04/22/2022] [Indexed: 06/14/2023]
Abstract
A hierarchically ordered macroporous RuO2 electrode (HOM-RuO2) was fabricated to enhance in situ active chlorine production in an electrochemical system intended for treatment of pharmaceutical active compounds (PhACs). The unique structure of HOM-RuO2 resulted in a decrease of the chlorine evolution potential, a large electro-active area available for in situ conversion of Cl- to active chlorine, and hence improved the active chlorine production by 40%. 5-Fluorouracil (5-FU) was used as a target pollutant to explore the performance of the HOM-RuO2 for PhACs degradation based on the in situ generated active chlorine. The results showed that the reaction rate of active-chlorine-mediated oxidation of 5-FU produced using the HOM-RuO2 was 18.4 times higher than that in the case of hydroxyl radicals (OH)-initiated oxidation using a PbO2 electrode at 30 mA cm-2. The effects of current density and initial solution pH on the 5-FU removal were investigated. The mechanism of 5-FU degradation was proposed taking into accounts both active chlorine production, and change of the speciation of 5-FU caused by pH variations. The dominant degradation products observed for the degradation of 5-FU using the HOM-RuO2 were lactic acid, propanol, acetic acid, urea and other small molecules, but no chlorinated products were detected. These study demonstrates the promise of the HOM-RuO2-based electrochemical systems for the active-chlorine-mediated treatment of recalcitrant pharmaceuticals found in wastewater.
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Affiliation(s)
- Ruiqian Liu
- Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing, 210018, China
| | - Lu Wang
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China
| | - Ruiqin Wu
- Beijing Xinzhiheng Technology HoldIngsCO., LTD, Bejing, 10080, China
| | - Siqi Liu
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China; Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, 98195-2700, United States.
| | - Gregory V Korshin
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, 98195-2700, United States
| | - Weiqing Han
- Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
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Xie J, Zhang C, Waite TD. Hydroxyl radicals in anodic oxidation systems: generation, identification and quantification. WATER RESEARCH 2022; 217:118425. [PMID: 35429884 DOI: 10.1016/j.watres.2022.118425] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 03/17/2022] [Accepted: 04/05/2022] [Indexed: 06/14/2023]
Abstract
Anodic oxidation has emerged as a promising treatment technology for the removal of a broad range of organic pollutants from wastewaters. Hydroxyl radicals are the primary species generated in anodic oxidation systems to oxidize organics. In this review, the methods of identifying hydroxyl radicals and the existing debates and misunderstandings regarding the validity of experimental results are discussed. Consideration is given to the methods of quantification of hydroxyl radicals in anodic oxidation systems with particular attention to approaches used to compare the electrochemical performance of different anodes. In addition, we describe recent progress in understanding the mechanisms of hydroxyl radical generation at the surface of most commonly used anodes and the utilization of hydroxyl radical in typical electrochemical reactors. This review shows that the key challenges facing anodic oxidation technology are related to i) the elimination of mistakes in identifying hydroxyl radicals, ii) the establishment of an effective hydroxyl radical quantification method, iii) the development of cost effective anode materials with high corrosion resistance and high electrochemical activity and iv) the optimization of electrochemical reactor design to maximise the utilization efficiency of hydroxyl radicals.
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Affiliation(s)
- Jiangzhou Xie
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Changyong Zhang
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia; CAS Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, 230026, China
| | - T David Waite
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia; UNSW Centre for Transformational Environmental Technologies, Yixing, Jiangsu Province, 214206, P.R. China.
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Dong H, Hu X, Zhang Y, Jiang W, Zhang X. Co/La modified Ti/PbO 2 anodes for chloramphenicol degradation: Catalytic performance and reaction mechanism. CHEMOSPHERE 2021; 285:131568. [PMID: 34710968 DOI: 10.1016/j.chemosphere.2021.131568] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 06/19/2021] [Accepted: 07/14/2021] [Indexed: 06/13/2023]
Abstract
Chloramphenicol (CAP) is widely used in daily life, and its abuse hurts human health, so a suitable method is needed to solve the problem. In this study, the Ti/PbO2 electrodes prepared by the electroplating method were characterized. The CAP degradation effect and mechanism were investigated. It was shown that the electrode surface had a dense plating with a characteristic peak of β-PbO2 as the active component. The electrode had an oxygen precipitation potential of 1.695 V and a corrosion potential of 0.553 V, and a long service life (505.4 d). The degradation of CAP at Ti/PbO2 electrode followed a first-order kinetic reaction. The optimal degradation conditions (current density of 12.97 mA cm-2, electrolyte concentration of 50 mM, and solution pH of 6.38) were obtained by the response surface curve method. The degradation rate of CAP was 99.0% at 60 min. The results showed that the reactive groups leading to CAP degradation were mainly ·OH and SO42-, and only a tiny portion of CAP was directly oxidized on the electrode surface. The addition of Cl- favored the degradation of CAP, but reduced the mineralization rate. LC-MS analysis showed that ·OH mainly attacked the asymmetric centers (C1, C2) of weakly bound hydrogen atoms, resulting in underwent addition and substitution reactions. CAP was converted into two substances with m/z = 306 and m/z = 165. Finally, inorganic substances such as CO2 and H2O were generated. This study provided a new idea for preparing Ti/PbO2 electrode with high performance and the safe and efficient degradation of CAP.
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Affiliation(s)
- Hao Dong
- College of Environmental Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China.
| | - Xuyang Hu
- College of Environmental Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China.
| | - Yinghao Zhang
- College of Environmental Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China.
| | - Wenqiang Jiang
- College of Environmental Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China.
| | - Xuan Zhang
- College of Environmental Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China.
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