Decolorization of C.I. Acid Blue 9 solution by UV/Nano-TiO 2, Fenton, Fenton-like, electro-Fenton and electrocoagulation processes: A comparative study

Abstract

This study makes a comparison between UV/Nano-TiO 2, Fenton, Fenton-like, electro-Fenton (EF) and electrocoagulation (EC) treatment methods to investigate the removal of C.I. Acid Blue 9 (AB9), which was chosen as the model organic contaminant. Results indicated that the decolorization efficiency was in order of Fenton > EC > UV/Nano-TiO 2 > Fenton-like > EF. Desired concentrations of Fe 2+ and H 2O 2 for the abatement of AB9 in the Fenton-based processes were found to be 10 −4 M and 2 × 10 −3 M, respectively. In the case of UV/Nano-TiO 2 process, we have studied the influence of the basic photocatalytic parameters such as the irradiation time, pH of the solution and amount of TiO 2 nanoparticles on the photocatalytic decolorization efficiency of AB9. Accordingly, it could be stated that the complete removal of color, after selecting desired operational parameters could be achieved in a relatively short time, about 25 min. Our results also revealed that the most effective decomposition of AB9 was observed with 150 mg/l of TiO 2 nanoparticles in acidic condition. The effect of operational parameters including current density, initial pH and time of electrolysis were studied in electrocoagulation process. The results indicated that for a solution of 20 mg/l AB9, almost 98% color were removed, when the pH was about 6, the time of electrolysis was 8 min and the current density was approximately 25 A/m 2 in electrocoagulation process.