Remediation of effluents polluted with toxic heavy metals using Cola nitida pod husk

Abstract

Felicia Uchechukwu Okwunodulu* and Stevens Azubuike Odoemelam

Heavy metal ions such as Cd2+, Ni2+ and Pb2+ are highly toxic to the entire ecosystem and are mostly produced by several industrial sectors. This study was designed to remove the listed heavy metal ions from an aqueous solution using Cola nitida waste for the batch adsorption process. The waste materials were employed in both raw and modified forms. The results obtained indicated that the adsorption capacity was influenced by initial metal ion concentration and adsorbent dose at a particle size of 250 µm, pH of 7.5, temperature of 25 0C and period of contact. The extent of adsorption of Cd2+, Ni2+ and Pb2+ by unmodified and modified waste Cola nitida waste was observed to increase with an increase in concentration and with a decreasing dosage of the adsorbent. At an initial metal ion concentration of 100 mg/l and adsorbent dose of 2g and 3g, maximum adsorptions by the unmodified and modified Cola nitida wastes were recorded for Cd2+ and the values obtained were 99.800+0.418 and 99.999+0.499; 89.999+3.439 at 3g and 99.952+0.166 at 2g. The adsorption behaviour of both the unmodified and modified Cola nitida wastes fitted the tested Freundlich and Temkin adsorption models best and suggested the dominancy of the mechanism of physisorption