Phenol removal from synthetic wastewater with powdered activated carbon: Isotherms, kinetics and thermodynamics

Abstract

Phenol is the 11th most toxic 126 chemical substance and causes cancer by accumulating in the food chain.Adsorption of phenol is an effective and also environmentally friendly method for its removal. In this study, phenolremoval by using powdered activated carbon (PAC) was optimized and modeled for various isotherms at constantmixing rate (150 rpm) and sample volume (100 mL); adsorbent dose (0.01-2 g), contact time (1-180 min), and initialphenol concentration (50-1000 mg $L^{-1}$). Moreover, adsorption studies were carried out at different temperatures forkinetic and thermodynamic calculations. In this study, optimum adsorbent dose and contact time of PAC weredetermined as 0.3 g 100 $mL^{-1}$ (3 g $L^{-1}$) and 10 minute, respectively. It can be concluded that it provides dischargestandards for a wastewater containing 100 mg $L^{-1}$ phenol. It was observed that the adsorption capacity decreased withincreasing temperature and the adsorption process fits well with Langmuir isotherm. It has been concluded that theadsorption of phenol with PAC is an exothermic reaction. As a result of the kinetic studies, it was found to be suitablefor the Pseudo Second Order ($R^2$ 0.9999-1.0000). ∆S, ∆H and ∆G were calculated as -0.02 J $mol^{-1}$ $K^{-1}$, -14.15 kJ$mol^{-1}$and between -8.16 and -7.76 kJ $mol^{-1}$, respectively.