Empirical modeling and kinetic study of methylene blue removal from synthetic wastewater by activation of persulfate with heterogeneous Fenton-like process

Abstract

The oxidative removal of methylene blue (MB) from synthetic textile wastewater was evaluated using a combination of persulfate and heterogeneous Fenton-like (PS-HFL) process. During batch experiments, the influential variables, including solution pH, initial MB concentration, reaction time, H2O2, goethite, and PS dose, were assessed. Also, an empirical model was employed to predict MB removal. MB removal's optimum conditions were obtained with an initial MB concentration of 350 mg/L solutions having pH of 6, H2O2 dose: 225 mg/L, goethite dose: 175 mg/L, PS dose: 200 mg/L, and 25 min reaction time, which lead to 99.4 ± 0.5% of MB removal. Furthermore, MB removal efficiency was also highly influenced by a dose of H2O2 and goethite, and PS. When goethite was reused for 5 cycles, the MB removal efficiency was still as high as 93%, implying goethite's good reusability. The radical trapping experiments indicated that hydroxyl radicals were the dominant radical for MB removal. The empirical model has given a coefficient of determination (r2) of 0.88 and could effectively define the behavior of MB removal efficiency by the PS-HFL process under different conditions. The present study's findings elucidated a new pathway of PS activation, which could degrade MB efficiently from synthetic textile wastewater.