Adsorption of Copper Ions from Aqueous Solution onto Natural and Pretreated Maize Husk: Adsorption Efficiency and Kinetic Studies

Abstract

The potential of chemical pretreatment of maize husk for the adsorption of copper ions from aqueous solution was studied and compared. Maize husk biomass (H) was pretreated with tartaric acid (HT), methanoic acid (HM) and phenol (HP). Initial elemental analysis of the husk using energy dispersive X-ray showed that the biomass contained 0.1 % copper in its natural form, and after adsorption, the percentage content of copper in the biomass materials increased in the order 17.7 %, 18.8 %, 24.6 % and 26.3 % for HP, H, HT and HM respectively. The removal efficiency of copper ions had maximum value 92 % with HM against 74 % obtained for H. The copper ion adsorption kinetics followed the pseudo second-order model for all the biomass types studied. Equilibrium adsorption capacity of H was 11.521 mg/g, and increased to a maximum value of 35.714 mg/g when pretreated with methanoic acid. Methanoic acid pretreated maize husk could therefore serve as an efficient and low-cost biomaterial for the remediation of copper ion polluted water.  Keywords: Copper ions, Methanoic acid, Pretreatment, Maize husk, Adsorption capacity