Synthesis of xanthated chitosan beads for fast and efficient recovery of precious Ce(III) ions from aqueous solutions

Xanthated chitosan (XC) beads, an efficient adsorbent to recover precious rare earth Ce(III) ions were prepared, characterized, and applied in this study. Factors that influence the performance in adsorption of Ce(III), which were pH of the solution, stirring rate, adsorbent dosage, and contact time, were investigated. Results revealed that the optimum conditions for adsorption of Ce(III) to be at a temperature of 300 K and pH 4, with a dosage of 0.02 g. A rapid adsorption process with only 10 min to achieve equilibrium was observed, regardless of the initial concentrations in Ce(III). Chemisorption was suggested as the rate-limiting step because of the correlation between Ce(III) adsorption process with the pseudo-second-order kinetic model. Langmuir model was found to fit well with the experimental isotherm data, and the maximum adsorption capacity of XC beads was 555.6 mg g(-1) at 300 K. Based on the thermodynamic study, the enthalpy and entropy recorded were -6.18 kJ mol(-1) and 130.36 J K-1 mol(-1), respectively. The nature of adsorption was exothermic as more Ce(III) ions were adsorbed at a lower temperature. Ion exchange, ionic attraction, and complexation were identified as the dominant mechanisms involved in Ce(III) adsorption.