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

  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.

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.

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.

 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.