Adsorptive removal of uranium from aqueous solution using chitosan-coated attapulgite

Chitosan-coated attapulgite beads were prepared by coating chitosan on naturally and abundantly available attapulgite, and made into spherical beads to adsorb uranium from aqueous solutions. The beads were characterized by SEM, EDS and FT-IR. The characteristics of beads of adsorbing uranium(VI) from aqueous solutions were studied at different conditions of pH, initial uranium concentration, contact time, biomass dosage and temperature. The pseudo-second order rate equation was used to describe the kinetic data, and isotherm data were fitted to Langmuir and Freundlich adsorption models. Thermodynamic parameters (ΔG°, ΔH°, and ΔS°) of the biosorption were also calculated. Thermodynamic parameters of the CAAB, viz., ΔG°(308 K), ΔH°, and ΔS° were determined to be −21.59, 6.29l and 90.51 J/mol K, respectively. The experimental results demonstrate that the beads of chitosan coated onto attapulgite exhibit considerable potential for application in both adsorption and removal of uranium from aqueous solutions.