Adsorption of malachite green in aqueous solution onto sodium carbonate treated rice husk

The feasibility of using rice husk for removing malachite green (MG) from aqueous solutions has been investigated as a low cost and an eco-friendly adsorbent. The effect of chemical treatment of rice husk by sodium carbonate was investigated through SEM and FTIR. As well, the effect of various factors like rotational speed, pH value of solution, temperature, initial concentration of dye, dose of adsorbent, contact time on the adsorption of MG was examined in batch experiments. Adsorption isotherms, kinetics, mass transfer and rate limiting steps are studied in detail. Adsorption thermodynamic parameters, activation energy and isosteric heat of adsorption were also studied. The adsorption was a spontaneous, endothermic and followed the pseudo-second-order kinetic model. The mechanism of adsorption and the COD aspect in deciding the effectiveness of the biomaterial as an adsorbent for dyes has also to be taken into account.