Adsorption Study of Lead(II) Ions onto Dichrostachys cinerea

Abstract

Dichrostachys cinerea was used in this work for removing Pb (II) ions from an aqueous solution. Batch adsorption studies were carried out under varying temperature, pH, initial ion concentration, contact time and adsorbent dosage. Adsorbent dosage of 0.5g showed an optimum adsorption capacity of 99.98% and 99.99% for contact time of 30 min and an initial concentration of 60 mg/l, respectively. Langmuir and Freundlich isotherms were used to model the equilibrium sorption experimental data. Langmuir isotherm yielded the best fit to the experimental equilibrium adsorption data with correlation coefficient (R2) of 0.998 under the effect of varying pH. The thermodynamic parameter, Gibbs free energy (ΔGo), was evaluated, and it was found that the adsorption process was spontaneous, feasible and exothermic. Therefore, this experiment showed that Dichrostachys cinerea could effectively be used as a low-cost adsorbent for the removal of lead (II) ions from an aqueous solution.