Iron oxide impregnated sugarcane bagasse waste material as sorbent for As(III) removal from water: kinetic, equilibrium and thermodynamic studies

Adsorption of arsenite (As(III)) from aqueous solutions onto iron oxide impregnated sugarcane bagasse was investigated in this study. The linear regression analysis showed that Langmuir adsorption isotherm fitted well to the experimental data. Langmuir constants ‘a’ related to the adsorption capacity and ‘b’ related to the binding energy of sorption system were found to be 1.55 mg/g and 46.44 L/mg, respectively. A kinetic study revealed that uptake of As(III) was rapid in the first 30 min after which it slowed down and became almost constant after 90 min, indicating that the equilibrium had been reached. Kinetic data correlated well with the pseudo-second order kinetic model, suggesting that the adsorption process might be chemisorption. Estimated pseudo-second order kinetic rate constant was 2.113 g/mg min. Evaluation of thermodynamic parameters (ΔG, ΔH, ΔS) indicated that the adsorption process was feasible and endothermic in nature.