Parametric study on the effect of the ratios [H2O2]/[Fe3+] and [H2O2]/[substrate] on the photo-Fenton degradation of ationic azo dye Basic Blue 41

An experimental parametric study was carried out to investigate the effects of [H2O2], [Fe3+] and [H2O2]/[Fe3+] ratio on the photo-Fenton degradation of a azo dye Basic Blue 41 (BB41) in aqueous solution. This method consists of coupling between Fenton's reagent and UV irradiation in order to catalyze the in situ generation of hydroxyl radicals, a powerful oxidizing agent which leads to degradation of organic pollutants until total mineralization. The kinetics study of the reaction between BB41 and hydroxyl radicals showed that the degradation of BB41 follows the first-order kinetics. It was found that the concentration of H2O2 and ferric iron as well as their ratio [H2O2]/[Fe3+] are key factors governing the removal of BB41 in aqueous medium and that the optimal ratio [H2O2]/[Fe3+] is equal to 10 for 0.2 mM Fe3+ concentration. The initial BB41 concentration and the [H2O2]/[BB41] ratio are also found as significant operating parameters on the mineralization efficiency. The optimization of the operating conditions permitted to obtain a quasi-total mineralization of synthetic BB41 aqueous solutions. When these optimal conditions were applied to the real wastewater, 90% of TOC removal was obtained after 8 h of irradiation time.