Adsorption of thorium (IV) ions from aqueous solution by magnetic chitosan resins modified with triethylene-tetramine

The triethylene-tetramine modified magnetic chitosan sorbents (TETA-MCS) were synthesized for the adsorption of Th(IV) ions from aqueous solution. FTIR analysis indicated that the amine and hydroxyl groups of TETA-MCS were involved in the adsorption process for the formation of O, N-Th(IV) complex. Th(IV) adsorption was pH dependent and the maximum adsorption was observed at pH 4.0. The adsorption kinetic data could be interpreted by pseudo-second-order kinetic model. The equilibrium data were correlated with the Langmuir, Freundlich and Temkin models, and the maximum monolayer adsorption capacity obtained from the Langmuir model was 133.3 mg Th(IV)/g at 25 deg C. Thermodynamic parameters revealed the feasibility, spontaneity and endothermic nature of adsorption. The sorbents were successfully regenerated using 0.2 M HNO3-0.1 M EDTA and exhibited good reusability. (author)