Optimization and modeling of decolorization and COD reduction of reactive dye solutions by ultrasound-assisted adsorption

The treatments of wastewaters contained dyestuffs are difficult and they require special advanced treatment technologies. It is known that adsorption is one of the methods commonly and efficiently used for treatment of textile wastewaters. In this study, the removal of reactive dye rifacion yellow HE4R was studied by using both ultrasound and combined ultrasound/activated carbon. The effects of relevant parameters, namely; ultrasound power, temperature, time, activated carbon concentration, dye concentration and initial pH have been investigated on the decolorization and COD reduction by using the fractional factorial design and the orthogonal central composite design. A model has been obtained among decolorization, COD reduction and relevant parameters by means of variance analysis by using the matlab computer software and obtained model was optimized. 80.62% decolorization efficiency was accomplished by ultrasound. Afterwards, combined ultrasound/activated carbon were applied to remove all dye color and COD from synthetic textile wastewater. The efficiencies of decolorization and COD reduction were accomplished at optimum conditions as 99.9% and 85.22%, respectively.