Degradation of Reactive Black 5 by Fenton/UV-C and ferrioxalate/H 2O 2/solar light processes

Abstract

The feasibility of employing different photoxidation systems, like Fenton/UV-C and ferrioxalate/H 2O 2/solar light in the decolorization and mineralization of an azo dye, has been investigated. Batch experiments were carried out to evaluate, on the first stage, the influence of different processes on Reactive Black 5 (RB5) decolorization. During the second stage were investigated the optimal operational conditions of Fenton/UV-C and ferrioxalate/H 2O 2/solar light processes, like pH, H 2O 2 dosage, iron dosage, RB5 concentration and source of light. The experiments indicate that RB5 can be effectively decolorized using Fenton/UV-C and ferrioxalate/H 2O 2/solar light processes with a small difference between the two processes, 98.1% and 93.2%, respectively, after 30 min. Although there is lesser difference in dye decolorization, significant increment in TOC removal was found with Fenton/UV-C process (46.4% TOC removal) relative to ferrioxalate/H 2O 2/solar light process (29.6% TOC removal). This fact reveals that UV-C low-pressure mercury lamp although with its small effect on dye decolorization is particularly important in dye mineralization, when compared to solar light. However, ferrioxalate/H 2O 2/solar light system shows large potential on photochemical treatment of textile wastewater with particular interest from the economical point of view.