Wet air and catalytic wet air oxidation of several azodyes from wastewaters: the beneficial role of catalysis

Abstract

Degradation of several azo dyes, Acid Orange 7 (AO7), Acid Orange 74 (AO74), Direct Blue 71 (DB71), Reactive Black 5 (RB5) and Eriochrome Blue Black B (EBBB), well-known non-biodegradable mono, di and tri azo dyes has been studied using, wet-air oxidation (WAO) and catalytic wet air oxidation (CWAO). The efficiency of substrate decolorization and mineralization in each process has been comparatively discussed by evolution concentration, chemical oxygen demand, total organic carbon content and toxicity of dyes solutions. The most efficient method on decolorization and mineralization (TOC) was observed to be CWAO process. Mineralization efficiency with wet air and catalytic wet air oxidation essays was observed in the order of mono-azo > di-azo > tri-azo dye. Final solutions of CWAO applications after 180 min treatment can be disposed safely to environment.