Thermodynamic and Isothermal Studies of the Biosorption of Cadmium (II) from Solution by Maize Wrapper

Abstract

The removal of Cd (II) from dilute aqueous solution using maize (Zea mays) wrapper as a biosorbent was studied. The biosorption was pH-dependent with an optimum pH of 5 - 7. It was also time-dependent and maximum biosorption was obtained after 100 minutes. The adsorption isotherms obtained fitted well into the Freundlich and Langmuir isotherms. The Freundlich equation obtained was log = 1.0813 logCe + 0.958 while the Langmuir equation obtained was 1/ = 0.1535/Ce – 0.013. The correlation factors were 0.99 and 0.99, while the standard deviation values were 0.051and 0.003 respectively. The free energy change obtained for the biosorption at 300 K, initial Cd (II) concentration of 100mg L-1 was –7.11kJmol-1. These results indicate that maize wrapper has the potential for the uptake of Cd (II) from industrial effluents.