A comparative study on the performance of photo/sono/peroxone processes for the removal and mineralization of reactive dye red 198 from aquatic environments

Abstract

Colored wastewater is the most important problem of textile manufacturing factories, because it contains pollutants with complex structure and toxic, carcinogenic, and mutagenic properties which are non-biodegradable and sustainable in the environment. Reactive Red 198 (RR198) is one of the types of azo dyes which are widely used in the textile industries. Therefore, in this study, the rate of degradation and mineralization of RR198 by UV/US/H2O2/O3 hybrid process was investigated. Influencing factors including: initial dye concentration (100, 200, 300, 400, 500 mg/L), contact time (12.5, 30, 47.5, 65, 82.5 min), pH (3, 5, 7, 9, 11), UV (125-W), H2O2 (10, 20, 30, 40, 50 mg/L), US (160 KHz) and O3 (33 mg/(L·min)) on the removal and mineralization efficiency of RR198 were investigated. Optimization and modeling of the process was done by CCD method. Based on the results of ANOVA analysis, most effective parameters on the RR198 removal efficiency were ozone, US, UV, time, initial dye concentration, pH, and H2O2, respectively, with an impact percentage of 96.86 and less than 1% for ozone and the rest parameters, respectively. Highest removal efficiency of RR198 was obtained by UV/US/H2O2/O3 hybrid process. Optimal conditions for dye removal including: initial dye concentration of 200 mg/L, reaction time of 34 min, H2O2 concentration of 27 mg/L and pH of seven were determined in the presence of ozone gas, UV, and US waves. In these conditions, the removal efficiency of RR198 and TOC were estimated to be 100 and 40.5, respectively. UV/US/H2O2/O3 hybrid process as an advanced oxidation process (AOP) with advantages such as high performance and speed, no sludge production and toxic residues in the treated effluent containing hard biodegradable compounds such as RR198 from aqueous solutions, so can be recommended and used.