Degradation of 4-chlorophenol from aqueous solution using ultrasound/persulphate: prediction by RSM

Abstract

ABSTRACT Chlorophenol compounds are considered as toxic and harmful effects caused by them have been proven for human and living organisms. This study is aimed to reduce 4-chlorophenol from aquatic solution using ultrasound/persulphate technique. Response surface method (RSM) is applied to find out the optimum conditions for 4-chlorophenol removal. The independent variables are pH, contact time, 4-chlorophenol concentration, persulphate concentration and ultrasound power. A statistical analysis of variance (ANOVA) is conducted to optimise factors obtained from the experimental data. A second-order model is developed as a great model to predict of 4-chlorophenol reduction efficiency. The optimum conditions is found at pH = 3, reaction time of 65 min, 4-chlorophenol concentration of 15 mg/l, persulphate concentration of 125 mg/L and ultrasound power of 150 W. In terms of 4-chlorophenol removal efficiency R2, Adj. R2 and coefficient of variance (CV) are found to be 0.95, 0.85 and 8.9, respectively. According to the results pH (A), reaction time (B), initial 4-chlorophenol concentration (C), persulphate concentration (D), ultrasound power (E), square terms of pH (A2), reaction time (B2), initial 4-chlorophenol concentration (C2), persulphate concentration (D2), ultrasound power (E2) and interaction terms of AB, AC, AD, BC, BD, CD, AE,and DE are found as effective factors. The results obtained from the extra experiments at optimal conditions indicates 88.92% removal rate of 4-chlorophenol which confirms a great agreement between the predicted (90.88%) and experimental data.