Cd2+ removal from synthetic waters by ZnCl2-activated carbon

A low-cost industrial biomass, pine-fruit residue (PFR) was utilized in preparing porous activated carbon by ZnCl2-impregnation followed by physically activation under inert atmosphere. The ZnCl2-activated carbon (ZnAC) was characterized for proximate analysis, surface properties, and used in removal of Cd2+ from synthetic waters. Experiments investigated the influence of pH, temperature and contact time in establishing the optimum Cd2+ sorption conditions. Temperature dependent equilibrium adsorption data were modelled using non-linear regression in the range 303-323 K. Equilibrium Cd2+ removal intake of 94.2 mg.g(-1) was achieved at 323 K and adsorption followed the Langmuir isotherm. Synthetic water pH, 7.0 and temperature, 323 K was observed optimum for saturated monolayer Cd2+ sorption capacity. Adsorption kinetics was more favourably described by Pseudo-second-order kinetic model. Thermodynamic parameter estimation indicated Cd2+ sorption process was spontaneous, endothermic and chemisorption phenomenon. The alterations in surface morphology of ZnAC were observed using filed-emission scanning electron microscopy (FE-SEM) integrated with elemental mapping from energy diffraction X-ray (EDX). (C) 2021 Elsevier Ltd. All rights reserved.