Optimization of 2-Chlorophenol Removal Using Ultrasound/Persulfate: Prediction by RSM Method, Biodegradability Improvement of Petrochemical Refinery Wastewater

Abstract

Chlorophenol compounds have the potential to cause significant environmental and health effects. In this research, response surface methodology (RSM) was utilized to find out the optimum condition for the oxidation of 2-chlorophenol using ultrasound/persulfate treatment technique. Contact time, pH, 2-chlorophenol concentration, persulfate concentration, and ultrasound power are considered as independent variables. The optimization of factors found from the experimental data is conducted by analysis of variance (ANOVA). A quadratic polynomial model is suggested as the best model in terms of statistical significance for 2-chlorophenol removal efficiency prediction. Reaction time = 65 min, pH = 3, 2-chlorophenol concentration = 17 mg/L, persulfate concentration = 120 mg/L, and ultrasound power = 150 W are found as optimum condition under which 2-chlorophenol reduction efficiency is found to be 90.92. Determination of coefficient (R2) parameter was 0.93. The results demonstrated that the pH (A), reaction time (B), initial 2-chlorophenol concentration (C), persulfate concentration (D), ultrasound power (E), square terms of pH (A2), reaction time (B2), initial 2-chlorophenol concentration (C2), persulfate concentration (D2), ultrasound power (E2), and interaction terms of AB, AC, AD, BD, CD, AE, and DE were found as effective factors. The findings of the biodegradability variation of petrochemical refinery wastewater under ultrasound/persulfate treatment showed a remarkable increase in BOD5/COD ratio (0.14–0.57). It reveals that the process can be employed as a pretreatment step before biological processes to facilitate the biological treatment of the recalcitrant wastewater. © 2021, King Fahd University of Petroleum & Minerals.