Enhancing Aqueous Chlorate Reduction Using Vanadium Redox Cycles and pH Control
Jinyu Gao, Gongde Chen, Qi Fu, Changxu Ren, Cheng Tan, Haizhou Liu, Yin Wang, Jinyong Liu
Abstract
High Resolution Image Download MS PowerPoint Slide Chlorate (ClO 3 – ) is a toxic oxyanion pollutant from industrial wastes, agricultural applications, drinking water disinfection, and wastewater treatment. Catalytic reduction of ClO 3 – 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 V V and V IV precursors are reduced to V III in the aqueous phase (rather than immobilized on the carbon support) by Pd-activated H 2 . The V III/IV redox cycle is the predominant mechanism for the ClO 3 – reduction. Further reduction of chlorine intermediates to Cl – could proceed via V III/IV and V IV/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 V III 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.