Evaluation of Degradation Characteristics of Reactive Dyes by UV/Fenton,UV/Fenton/Activated Charcoal,and UV/Fenton/TiO2 Processes: A Comparative Study

The photochemical decolorization and mineralization of Reactive red 241 (RR241) in aqueous solution has been studied using a homogeneous photofenton process and its combination with activated charcoal and titanium dioxide. The effects of applied catalyst and adsorbent loading, dye concentrations, pH of solution, and the effect of various systems at constant UV irradiation were determined. Decolorization, COD and TOC analysis were employed to evaluate the results of the photochemical and photocatalytic degradation of RR241. The degradation of the dye was monitored by constant COD analysis and then analyzed by high performance liquid chromatography (HPLC) and IR analysis. The result shows that complete decolorization of dye with photofenton process required 240 minutes with 18.6% of maximum TOC reduction. To overcome the problem of slow decolorization and low degradation with photofenton process, it was combines with activated charcoal and Titanium dioxide. UV/Fenton/AC process gave complete decolorization in less than 80 minutes with 14.9% of TOC reduction after 240 minutes. In contrast the UV/Fenton/TiO₂ process required 120 minutes for complete decolorization but yielded maximum TOC reduction of 43.9% after 240 minutes. Therefore, according to COD and TOC reduction it could be suggested that the UV/Fenton/TiO₂ was more effective than other processes.