The sonochemical decolorisation of textile azo dye CI Reactive Orange 127

In the present study, Fenton and sono‐Fenton processes were applied to the oxidative decolorisation of synthetic textile wastewater including CI Reactive Orange 127 and polyvinyl alcohol. Process optimisation pH, ferrous ion (Fe²⁺) and hydrogen peroxide (H₂O₂)], kinetic studies and their comparison were carried out for both of the processes. The sono‐Fenton process was performed by indirect sonication in an ultrasonic water bath, which was operated at a fixed 35‐kHz frequency and 80 W power. The optimum conditions were determined as Fe²⁺] = 20 mg l^?1, H₂O₂] = 15 mg l^?1 and pH = 3 for the Fenton process and Fe²⁺] = 25 mg l^?1, H₂O₂] = 5 mg l^?1 and pH = 3 for the sono‐Fenton process. The colour removals were 89.9% and 91.8% by the Fenton and sono‐Fenton processes, respectively. The highest decolorisation was achieved by the sono‐Fenton process because of the production of some oxidising agents as a result of sonication. Consequently, ultrasonic irradiation in the sono‐Fenton process slightly increased the colour removal to 91.8%, while decreasing the hydrogen peroxide dosage to one‐third of that of the Fenton process.