Decolorization of Reactive Orange 122 as an Organic Pollutant by the Sonoelectrochemical Process and Toxicity Evaluation

Introduction: Combined of electrochemistry and ultrasound (sonoelectrochemistry) is one of the advanced oxidation processes (AOPs) for decolorization of color wastewaters. The physicochemical effects of ultrasound improve the electrooxidation of dye solution and decolorization rate. Materials and Methods: In this study, the decolorization of Reactive Orange 122 (RO122) as an organic pollutant by sonoelectrochemistry has been examined. In this context, the effect of several factors such as hydrogen peroxide concentration, the pH of solution, colour concentration, and the input voltage on decolorization of colourful solution as a single factor were studied. Based on the results, the optimum hydrogen peroxide concentration for removing the colour with the concentration of 10 mgL-1 at 90 minutes was 3.0 mgL-1, with pH about 7.0 and the input potential 1.05 V, the process was carried out without the use of hydrogen peroxide as a considered parameter at 90 minutes. Results: The results revealed that decolourization and removal of chemical oxygen demand (COD) of both methods were 99% and 70% in the presence of hydrogen peroxide and 97% and 95.5% in the absence of hydrogen peroxide, respectively. Conclusions: Microbial toxicity test assessed the toxicity of intermediates produced during these two procedures. The results indicated, in the absence of hydrogen peroxide, Pseudomonas aeruginosa bacteria showed better performance on sonoelectrochemical treatment solutions compared to the initial solution, due to absence of colour toxic materials