Adsorption of Pb (II) ion onto Modified Doum Palm (Hyphaene thebaica) Shells: Isotherm, Kinetic and Thermodynamic Studies

Abstract

The negative impact of high concentrations of lead in the analytical environment on humans and aquatic plants prompted this research. The adsorption of hazardous lead from an aqueous medium using a Modified Doum Palm (MDP) shell was investigated. The modification of the Doum palm shell was supported via 2 M 1: 2 ZnCl2 as activating agent. The batch equilibrium technique was employed to study the effect of initial concentration (800 mg/L), contact time (90 min) and temperature (313 K) on the adsorption capacity of the prepared adsorbent. Experimental data were analyzed using four kinetic models: pseudo-first-order, pseudo-secondorder, intra-particle diffusion and Elovich models and it was found that the pseudo-second-order model fitted the adsorption data most with the highest correlation (R2 = 0.9875). The studies of thermodynamic behaviour revealed negative values for ∆Go (-26.7036 to -28.1252 kJ/mol), and negative values for ∆Ho (-15.5796 kJ/mol) and ∆So (0.03554 kJ/mol/k) respectively. These indicated the adsorption process was exothermic, feasible and spontaneous in the removal of the Pb (II) ion. The findings demonstrated that the adsorbent could be exploited in the removal of Pb (II) ion from an aqueous solution.