Hybrid techniques for degradation of textile dyes by advanced oxidation processes

Abstract

Nowadays, the remediation of textile effluents containing persistent dye stuffs is still far away to a satisfactory solution. Consequently, the increased public concern and stringent regulations have challenged the scientist community to explore new lines to reduce environmental problems associated with such wastewater. A number of emerging decolorization technologies are being proposed and tested at different stages of commercialization. However, due to their synthetic origin and complex structure deriving from the use of different chromophoric groups, dyes are extremely recalcitrant. The present investigation is focused on degradation of Reactive Red 11 and Reactive Yellow 16, using Fenton and Electro-Fenton process, singly and in combination with ultrasound/ultraviolet irradiation. Optimization Studies by central composite design using Response Surface Methodology (RSM) were also carried out. Efficiency of hybrid systems was compared to select the best one and was applied for treating textile effluent. Fenton experiments were carried out to study the effect of change in parameters such as pH, Fe2+, H2O2 and dye concentration. Kinetic studies were also carried out. The effects of ultrasound and ultraviolet irradiation on Fenton s process were also carried out. Sono-Fenton process was found to be effective, compared to Fenton s process. Electro-Fenton process was also applied for the degradation of RR 11 and RY 16. The rate of degradation was found to be maximum in acidic medium. The average color and COD removal were 93 % and 76 % respectively. Response Surface Methodology was applied for batch operation and the results were analyzed and the regression model equation was obtained. From the results, it may be concluded that Fenton s process could be used successfully at lower dye concentrations and Photo-Electro-Fenton process could be used as an efficient and eco friendly technique at higher dye concentrations and for textile industry effluent.