Degradation of azo-reactive dyes by ultraviolet radiation in the presence of hydrogen peroxide

This paper summarizes the results of a degradation test of several azo-reactive dyes and cotton textile wastewater under UV irradiation in the presence of H2O2, Five of the most commonly used azo-reactive dyes from both the Levafix and Remazol types were tested. 4-1 Dye solutions of 100 mg/l were prepared immediately before irradiation. A batch mode water-jacketed immersion photoreactor was utilized. The radiation source was a 120 W UV lamp emitting at 253.7 nm and protected by a quartz tube. Complete destruction of the color of the dye solutions was succeeded in the first 20-30 min of irradiation. Almost all the aromatic rings and 80% of TOC were destroyed after 2 h of irradiation. The textile wastewater color was completely removed in less than 1 h while 90% of the aromatic rings and 70% of the wastewater COD were removed after 2 h of irradiation. UV/H2O2 proved capable of the complete degradation and mineralization of the above azo reactive dyes. (C) 2002 Elsevier Science Ltd. All rights reserved.