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Gao J, Chen G, Fu Q, Ren C, Tan C, Liu H, Wang Y, Liu J. Enhancing Aqueous Chlorate Reduction Using Vanadium Redox Cycles and pH Control. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:20392-20399. [PMID: 37976223 DOI: 10.1021/acs.est.3c06519] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
Chlorate (ClO3-) is a toxic oxyanion pollutant from industrial wastes, agricultural applications, drinking water disinfection, and wastewater treatment. Catalytic reduction of ClO3- using palladium (Pd) nanoparticle catalysts exhibited sluggish kinetics. This work demonstrates an 18-fold activity enhancement by integrating earth-abundant vanadium (V) into the common Pd/C catalyst. X-ray photoelectron spectroscopy and electrochemical studies indicated that VV and VIV precursors are reduced to VIII in the aqueous phase (rather than immobilized on the carbon support) by Pd-activated H2. The VIII/IV redox cycle is the predominant mechanism for the ClO3- reduction. Further reduction of chlorine intermediates to Cl- could proceed via VIII/IV and VIV/V redox cycles or direct reduction by Pd/C. To capture the potentially toxic V metal from the treated solution, we adjusted the pH from 3 to 8 after the reaction, which completely immobilized VIII onto Pd/C for catalyst recycling. The enhanced performance of reductive catalysis using a Group 5 metal adds to the diversity of transition metals (e.g., Cr, Mo, Re, Fe, and Ru in Groups 6-8) for water pollutant treatment via various unique mechanisms.
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Affiliation(s)
- Jinyu Gao
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Gongde Chen
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Qi Fu
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry/KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-Sen University, Guangzhou, Guangdong 510275, China
| | - Changxu Ren
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Cheng Tan
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Haizhou Liu
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Yin Wang
- Department of Civil and Environmental Engineering, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, United States
| | - Jinyong Liu
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
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Abstract
Polarograms taken in solutions of vanadium (II) perchlorate, 0.10 N with respect to perchloric acid and at an ionic strength of 0.20, indicate that vanadium (II) exists predominately as a dimer in the concentration region of 5 millimolar. Oxidation of one of these ions appears to make the second relatively inert towards oxidation until labilized by further oxidation of the first to vanadyl ion.No indication of complex formation of vanadium (II) was found with sulphate, chloride, iodide, or bromide ions. The existence of fluoro and thiocyanato complexes was noted, the vanadium (II) complexes having lower formation constants than the corresponding vanadium (III) complexes.
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Taube H. Mechanisms of Redox Reactions of Simple Chemistry. ADVANCES IN INORGANIC CHEMISTRY AND RADIOCHEMISTRY 1959. [DOI: 10.1016/s0065-2792(08)60251-4] [Citation(s) in RCA: 77] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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