ABSTRACT: In this work, four Fenton processes were used for decolorization of titan yellow. Experimental conditions such as concentration of H2O2, pH, time, zero valent iron dose and concentration of Fe2+ were optimized by Doehlert experimental design and response surface models. In absent of ultrasonic waves, application of zero valent iron had intense effect on decolorization percent (95% for heterogeneous Fenton with respect to 18% for classical Fenton). The optimum conditions were (0.0054M H2O2, 0.031g/L Fe2+, pH 2.5 and reaction time 47 min) and (0.0013M H2O2, 0.194g/L zero valent iron, pH 2.5 and reaction time 10 min) for homogeneous and heterogeneous Fenton processes, respectively. Both homogeneous and heterogeneous Sono-Fenton processes reached to decolorization percent of 100%. Optimum pH was 2.5 for two processes. The optimum conditions for homogeneous and heterogeneous sono-Fenton processes were (0.0035M H2O2, 0.0037g/L Fe2+, and reaction time 30 min) and (0.0014M H2O2, 0.4g/L zero valent iron, and reaction time 10 min), respectively.
