Adsorption of Heavy Metals in Wastewater using a Composite Adsorbent derived from Sugarcane Bagasse: Isotherm and Kinetic Studies

Abstract

This study investigates the adsorption potential of a composite adsorbent of chemically activated cellulose derived from sugarcane bagasse and Chitosan (CHIC) to remove heavy metals from its aqueous solution. The experimental equilibrium data were tested using isotherm models namely, Langmuir, Freundlich and Temkin. The adsorption kinetics and mechanism were also studied using pseudo-first order, pseudo-second order and Elovich to ascertain the behavior of the mechanism. It was found that experimental equilibrium data of Chromium, Copper, Cadmium and Iron followed the Freundlich model indicating multilayer sorption on a heterogenous surface. The higher the KF greater the adsorption intensity. The higher KF values exhibit by the adsorption of Fe suggests that Fe has greater adsorption tendency towards the adsorbent. The maximum multilayer sorption capacity at 303 K was estimated to be 1.345 L/g. In addition, the value of 1/n was below unity indicating that the surface of the adsorbate was heterogeneous, multilayer and the mechanism of adsorption was a chemisorption process. Whereas the adsorption of Lead followed Temkin model. Pseudo-second-order kinetic model provided a better correlation for the experimental data studied for all the metals in comparison to the pseudo-first-order model. The equilibrium data indicated that CHIC can be used as an effective and low-cost adsorbent to remove Metal ions from its solution.