Pb(II) adsorption mechanism and capability from aqueous solution using red mud modified by chitosan

Red mud modified by chitosan (RM/CS) was utilized as an adsorbent to effectively remove Pb(II) from aqueous solution. The surface area of RM/CS was found to significantly increase by more than 50% compared to that of original red mud. Different factors that affected the Pb(II) removal on this material, such as initial Pb(II) concentration, pH, and contact time, were investigated. The pseudo-first-order, pseudo-second-order, and intradiffusion models were used to fit the experimental data to investigate the Pb(II)'s removal kinetics. The Pb(II) removal followed the intra-diffusion model. Additionally, the non-zero C value obtained from this model indicates that the removal was controlled by many different mechanisms. We also found that the interaction of Pb (II) and carbonate group on the material's surface played a primary role once the adsorption equilibrium was reached. Finally, the maximum adsorptive capacity was found to be about 209 mg/g. This obtained value is higher than those obtained for some other materials. Therefore, the present RM/CS should be a potential material for removing Pb(II) from aqueous solution.

Automated summary

In this study, red mud modified by chitosan (RM/CS) was found to be an effective adsorbent for removing Pb(II) from aqueous solution, with a significantly increased surface area and high maximum adsorptive capacity. The adsorption process was mainly controlled by intra-diffusion mechanisms, and the interaction between Pb(II) and carbonate groups on the material's surface played a primary role once adsorption equilibrium was reached. The results suggest that RM/CS has potential as a material for removing Pb(II) from aqueous solution.