Treatment of wastewater containing toxic chromium using new activated carbon developed from date palm seed

Abstract

The use of a new activated carbon developed from date palm seed wastes, generated in the jam industry, for removing toxic chromium from aqueous solution has been investigated. The activated carbon has been achieved from date palm seed by dehydrating methods using concentrated sulfuric acid. The batch experiments were conducted to determine the adsorption capacity of the biomass. The effect of initial metal concentration (25–125 mg l −1), pH, contact time, and concentration of date palm seed carbon have been studied at room temperature. A strong dependence of the adsorption capacity on pH was observed, the capacity increase as pH value decrease and the optimum pH value is pH 1.0. Kinetics and adsorption equilibrium were studied at different sorbent doses. The adsorption process was fast and the equilibrium was reached within 180 min. The maximum removal was 100% for 75 mg l −1 of Cr 6+ concentration on 4 g l −1 carbon concentration and the maximum adsorption capacity was 120.48 mg g −1. The kinetic data were analyzed using various kinetic models – pseudo-first order equation, pseudo-second order equation, Elovich equation and intraparticle diffusion equation – and the equilibrium data were tested using several isotherm models, Langmuir, Freundlich, Koble–Corrigan, Redlich–Peterson, Tempkin, Dubinin–Radushkevich and Generalized isotherm equations. The Elovich equation and pseudo-second order equation provide the greatest accuracy for the kinetic data and Koble–Corrigan and Langmuir models the closest fit for the equilibrium data. Activation energy of sorption has also been evaluated as 0.115 and 0.229 kJ mol −1.