Study of O₃/S₂O₈²- Advanced oxidation processes (AOPs) for removal of dye industrial effluents

Abstract

This research was carried out to study the efficiency of O₃/S₂O₈²- system in treating the synthetic dye wastewater. Different operating parameter: pH, initial dye concentration and persulfate dosage were studied to investigate the effect on colour and COD removal efficiency. The UV-vis spectra and functional group evaluation before and after the treatment were presented. From experimental works, the O₃/S₂O₈²- achieved better results in decolourization and degradation of Reactive Red 120 (RR120) dye sample than O₃, where complete removal of colour and COD was achieved at 4 and 20 minutes, respectively. While fully decolourization happened only after 5 minutes and mineralization was unable obtained after 20 minutes for ozonation treatment. Next, pH 7 was chosen as the suitable pH as increasing of pH has little effect on the concentration. Furthermore, low initial dye concentration seems to obtain a significantly percentage of reduction than higher concentration. 5 g S2O82-/1 g RR120 was chosen as the optimum dosage due to it have the better colour and COD reduction among others dosage tested. Next, O₃/S₂O₈²- experienced faster degradation of azo bond and aromatic compounds than O₃ after treatment as observed with UV–Vis absorption spectra. Furthermore, the FT-IR analysis showed that there have new absorption peak that represents alkenes after 20 minutes of O₃ treatment whereas mostly of the absorption bands of O₃/S₂O₈²- was flattened. As a conclusion, O₃/S₂O₈²- can decolourization and mineralization effectively in a short treatment time than ozonation.