Evaluation of magnetic ZSM-5 composite performance in 2, 4 dichlorophenol removal from synthetic solutions: response surface method (RSM) modeling and isotherm, kinetic and thermodynamic studies

Abstract

2,4-Dichlorophenol (DCP) is a chlorinated derivative of phenol that causes harmful effects on human health even at low its concentrations. The aim of this study was to investigate the adsorption of the compound from synthetic wastewater by magnetic ZSM-5 (ZSM-5/M) composite in a laboratory scale, in a batch system. The SEM, XRD and EDX analyses were used to evaluate the quality characteristics of ZSM-5/M composite. The variables effect of pH, contact time (min), dose of ZSM-5/M (g/L) and pollutant concentration (mg/L) was investigated on the adsorption process under surface response method (RSM) at 5 levels during 30 experiments. In order to measure the DCP concentration, Perkin Elmer LAMBDA 25 UV/Vis spectrophotometer was used at 580 nm wavelength. Isotherm, kinetic and thermodynamic studies of adsorption process were also performed in the optimal conditions of the variables. Diagnostic analyses showed the ZSM-5/M was successfully synthesized. At the optimum level of pH, contact time, ZSM-5/M dose, and DCP concentration to be 6.3, 120 min, 1 g/L and 10 mg/L respectively, the maximum efficiency was obtained about 96. The adsorption process followed Freundlich isotherm (R-2 = 0.9967) and pseudo-first-order kinetic (R-2 = 0.9996), and the adsorption capacity was determined to be nearly 87.7 mg/g. Thermodynamic study illustrates that adsorption process has a spontaneous and exothermic nature. Owning to high efficiency, appropriate adsorption capacity, low cost, and the easy separation, regeneration, and reuse of the adsorbent after the adsorption process, ZSM-5/M can be potentially suggested to be applied as a promising adsorbent in the adsorption of DCP and similar compounds from aquatic environments.