Sorption of Lead (II) and Copper (II) ions from aqueous solution by acid modified and unmodified Gmelina arborea (Verbenaceae) leaves

Abstract

Gmelina arborea leaves of tropical origin were modified with citric acid as esterifying agent and was used to selectively removed Pb(II) and Cu(II) ions from aqueous solution by batch adsorption method. The concentrations of the metal ions adsorbed were determined by atomic absorption spectroscopic (AAS) method. The citric acid had a strong significant effect on the removal of metal ions from solution because of an increase in the carboxyl groups introduced into the biosorbent. The amount of metal ions removed from solution was found to depend on the metal ion-substrate contact time, ion concentration and ion type. The results indicated that after 90 minutes contact time, the amount of adsorbed metal ion increased with increase in the initial metal ion concentration up to 20 mg/cm3. This also varied with the cellulosic materials in the order Pb(II)>Cu(II). The acid modified Gmelina arborea leaves adsorbed more metal ions than when unmodified. The equlibruim data fitted well to the Freundlich adsorption isotherm. The Gmelina arborea leaves were better adsorbents of Pb(II)ion than Cu(II) ion.