KINETIC AND EQUILIBRIUM STUDIES OF BIOSORPTION OF NICKEL AND COPPER BY CAMEL FOOT (PILIOSTIGMA THONNINGII) POD

Abstract

In recent years, the need for safe, efficient and economical methods for the elimination of heavy metals from contaminated waters has necessitated research interest toward the production of low cost alternatives to commercially available activated carbon which is highly expensive. The effectiveness of camel foot (Piliostigma thonningi) pod biomass for the removal of nickel and copper ions from aqueous solution was investigated using batch process under various experimental conditions of varying pH, contact time, initial metal ion concentration, particle size, temperature and biomass dose. The results obtained showed that optimum adsorption takes place at pH 4 for both nickel and copper ions with 78% and 72% removal at the optimum time of 4 h and 3 h for nickel and copper ions respectively. Kinetics studies showed that the adsorption of nickel and copper ions followed the pseudo second-order kinetics. The adsorption of nickel ions fitted well into the Langmuir isotherm while that of copper ions were best explained by Freundlich isotherm. The result of the investigation also revealed that the optimum percentage of heavy metal ions removal was obtained at 2.50 g biomass dose, at a particle size of 300 μm, optimum temperature range of 25-30 0C, and initial metal concentration of 50 mg/L. The survey showed that camel foot biomass is an efficient, economical and inexpensive adsorbent for the removal of Ni2+ and Cu2+ in the treatment of contaminated water and wastewater by chemical and allied industries.