Application of anodic oxidation, electro-Fenton and UVA photoelectro-Fenton to decolorize and mineralize acidic solutions of Reactive Yellow 160 azo dye

•Slow decolorization of Reactive Yellow 160 solutions by anodic oxidation with a BDD/air-diffusion cell.•Fast decolorization using electro-Fenton, even faster in UVA photoelectro-Fenton.•94-96% Mineralization by the most powerful UVA photoelectro-Fenton at 100mAcm−2.•Maleic, fumaric, tartronic, acetic, oxalic, oxamic and formic acids detected as products.•Cl−, SO42−, NH4+ and some NO3− formed from heteroatoms during azo dye mineralization The degradation of 100cm3 of a solution with 0.167mmoldm−3 Reactive Yellow 160 (RY160) azo dye in sulfate medium at pH 3.0 has been comparatively studied by anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF) and UVA photoelectro-Fenton (PEF). Trials were carried out with a stirred tank reactor equipped with a boron-doped diamond (BDD) anode and an air-diffusion cathode for H2O2 production, upon addition of 0.50mmoldm−3 Fe2+ as catalyst in EF and PEF. The solution was slowly decolorized by AO-H2O2 because of the low rate of reaction of the azo dye and its colored products with hydroxyl radicals generated at the BDD anode from water oxidation. The color loss was enhanced in EF by the larger oxidation ability of hydroxyl radicals produced in the bulk from Fenton’s reaction between added Fe2+ and generated H2O2, whereas the solution was more rapidly decolorized by PEF owing to the additional generation of hydroxyl radicals from the photolysis of Fe(III)-hydroxy complexes by UVA light. The relative mineralization ability of the processes also increased in the sequence AO-H2O2