Efficacy of Sulfate-based Advanced Oxidation Process (Microwave/Na2S2O8/Fe2+) for 4-Chlorophenol Removal from Aqueous Solutions

Abstract

Introduction and purpose: Chlorophenol is one of the most dangerous and toxic pollutants in industrial effluents and wastewater. The removal of this material from groundwater and surface water is considered a serious problem. This study aimed to evaluate the degradability of 4-Chlorophenol using microwave / Na2S2O8 / Fe2+ process. Methods: In this quasi-experimental study, the effects of variables, including initial pollutant concentration (0.5-5 mM), contact time (0-30 min), pH (3-11), persulfate concentration (8-80 mM), a dosage of Fe2+ (0.01-0.1 mM), and power output (180-600 W) were investigated on the removal of 4-chlorophenol in a modified domestic microwave. The residual 4-chlorophenol concentration was then measured using a spectrophotometer at 280 nm. The mineralization rate at optimum conditions was determined by assessing the total organic carbon (TOC) removal rate according to the B 5310 standard. Moreover, kinetic models of the process were investigated. Results: In this study, the optimum removal efficiency of 4-chlorophenol by microwave / Na2S2O8 / Fe2+ process was obtained at 91.38% at 60 mM sodium persulfate concentration, pH = 11, 0.5 mM initial concentration of 4-chlorophenol, and the presence of 600 W microwave radiation at 30 min exposure. In addition, it was revealed that 77% of TOC was removed at optimum conditions. The data followed the pseudo-first-order kinetic model. Conclusion: The MW / Na2S2O8 / Fe2+ process can be used as a post-treatment or final treatment of effluent considering the treatment objectives and existing standards for effluent discharge.

Keywords

• 4-chlorophenol
• iron (ii)
• microwave
• sulfate radical