Application of chitosan/Al2O3 nano composite for the adsorption of thorium (IV) ion from aqueous solution

Abstract

ABSTRACT In this study, novel chitosan/Al 2 O 3 nano composite (Ch/Al-O NCo ) was synthesized and evaluated as an adsorbent for removing thorium (IV) (Th 4+ ) ion from aqueous solution. The Ch/Al-O NCo was characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) , Fourier Transform Infrared (FT-IR) and Scanning Electron Microscopy (SEM) and the specific surface area of Ch/Al-O NCo were found to be 29.23 m 2 g –1 . Batch experiments were carried out under varying operating conditions namely adsorbent weight, contact time and initial pH. The optimum adsorbent weight was found to be 0.2 g L –1 while the adsorption process was found to be optimal in the wide pH range of 2–8. The adsorption kinetics was well described by the pseudo-second-order equation, when the Langmuir model better fit the adsorption isotherms. The adsorption capacity of Ch/Al-O NCo was 591.12 mg Th 4+ /g composite, leads to 99% removal at 25°C. Moreover, the calculated thermodynamic parameters including standard enthalpy, entropy, and Gibbs free energy indicates the spontaneous and endothermic nature of the adsorption process. The loaded Th 4+ can be easily regenerated with HNO 3 and the Ch/Al-O NCo could be used repeatedly without any significant reduction in its adsorption capacity. The desorption level of Th 4+ from the Ch/Al-O NCo , by using 0.1 M HNO 3 , was more than 94%.