Production of KOH-activated carbon from date press cake: effect of the activating agent on its properties and Pb(II) adsorption potential

Abstract

The aim of this study was to evaluate the efficiency of KOH-activated carbon derived from date press cake (DPC) for the adsorption of Pb(II) from aqueous solutions. Raw DPC was first converted into a carbonized material (CM) and then activated at dry KOH:CM weight ratios of 1:1 (AC1) and 4:1 (AC4). The adsorbents were characterized using FTIR, FESEM-EDX, BET and Boehm titration method. AC1 and AC4 showed microporous structure with BET surface areas of 1237.2 and 2938.7 m2 g–1, respectively. The prepared activated carbons (ACs) successfully adsorbed Pb(II) from aqueous solution with maximum monolayer adsorption capacities of 59.0 mg g–1 (AC1) and 101.3 mg g–1 (AC4). The adsorption of Pb(II) onto both ACs was well described by Elovich and pseudo-second order kinetic models, indicating that the rate of Pb(II) adsorption onto the ACs was mainly controlled by chemical adsorption. Isotherm study showed that the adsorption of Pb(II) onto AC1 took place in multilayer on a heterogeneous surface, while the Pb(II)/AC4 adsorption process occurred in a monomolecular layer with a homogenous distribution among the adsorption sites at different energies. This study showed that AC4 has a high specific surface area and successfully adsorbs Pb(II) even from saline aqueous solutions.