Electrochemical oxidation of azo dyes in water: a review

Pollution of waters by azo dyes is a major global issue because some azo dyes have carcinogenic and mutagenic effects. Therefore, advanced methods are required to remove those pollutants from wastewater. For instance, electrochemical oxidation processes have been developed using various approaches to remove azo dyes from wastewater. Here, we review electrochemical processes for the oxidative degradation of azo dyes. Processes include anodic oxidation, electro-Fenton, photo-electro-Fenton, and solar photo-electro-Fenton. The influence of various parameters including process design, design of reactors, and the characteristic degradation products and their toxicity, are discussed. Low molecular weight carboxylic acids are mainly formed as by-products.