Adsorption of uranium from aqueous solution using chitosan-tripolyphosphate (CTPP) beads.

Chitosan-tripolyphosphate (CTPP) beads were prepared using in-liquid curing method and used for the adsorption of uranium from aqueous solution. Beads were prepared at two different cross-linking densities by adjusting the pH of the tripolyphosphate solution. The synthesized beads were characterized using FTIR spectroscopy before and after adsorption of uranium. Beads having higher cross-linking are found to have better adsorption capacity for uranium. Factors that influence the uranium adsorption onto CTPP beads such as solution pH, contact time and initial uranium concentration were studied in detail. The experimental results were fitted into Langmuir and Freundlich adsorption isotherms. From Langmuir adsorption model the adsorption capacity of CTPP beads for uranium is estimated as 236.9 mg/g. Pseudo-first order, pseudo-second order and intraparticle diffusion model were applied to the observed kinetics data and the results shows that the pseudo-second order model is more suitable to explain the kinetics of adsorption of uranium on CTPP beads. FTIR spectroscopic characterization of the beads showed that the phosphate groups may be more responsible for the adsorption of uranium on CTPP beads.