Adsorption Capacity of Coconut (Cocos nucifera L.) Shell for Lead, Copper, Cadmium and Arsenic from Aqueous Solutions

This study explored the adsorption capacity of Coconut (Cocos nucifera L.) shell for Pb2 +, Cu2 +, Cd2 + and As3 + from aqueous solutions. The effect of various operational parameters such as concentration, pH, temperature and sorption time on the adsorption of Pb2 +, Cu2 +, Cd2 + and As3 + was investigated using batch process experiments. It was found that coconut shell (CNS) can be used as a low cost adsorbent for the removal of heavy metals in aqueous solution containing low concentrations of the metals. The maximum ion adsorption capacities followed the trend Pb2 +>Cu2 +>Cd2 + > As3 + and the percentage adsorption was found to depend on the concentration of the adsorbent present, the solution pH, temperature and the sorption. The average values of the activation energy of adsorption for CNS were 7.99, 3.79, 10.24 and 53.977KJ/mol for Pb, Cu, Cd and As respectively. This shows that the adsorption of metal ions on the adsorbent is physical adsorption mechanism. Kinetic treatment of the results gave a pseudo-second order type of mechanism while the adsorption characteristics of the adsorbent followed the Freundlich adsorption isotherm.