Temperature Swing Adsorption of Uranium (VI) ions on Poly (N-isopropylacry-lamide)/Chitosan Semi-IPN

Ya-Ting Liu ； Yun-Hai Liu ； Xiao-Hong Cao ； Rong Hua ； You-Qun Wang ； Qin Li

《International Journal of Nuclear Energy Science and Engineering》 1卷1期 (2011/12) Pp. 8-14

並列摘要

In this paper, thermo- sensitive semi-IPN (interpenetrating network) hydrogels were prepared by introducing chitosan (CS) as a metal ion receptor into the poly(N-isopropylacrylamide) (PNIPAAm) hydrogels with an IPN technique. The swelling behavior of the semi-IPN hydrogels under different temperatures was studied. Feasibility of U (VI) sorption using the prepared hydrogels were investigated at different optimized conditions of contact time, initial concentration of U (VI) and temperature. The kinetic study demonstrated that the pseudo-first-order model correlated with the experimental data better than the pseudo-second-order model examined. To discuss the mechanism of adsorption of uranium (VI) ions on the semi-IPN hydrogels at temperature above and below the lower critical solution temperature (LCST), Langmuir and Freundlich adsorption models were applied to describe the isotherms at 293 and 323 K. The Langmuir model correlates well with the U (VI) adsorption equilibrium data for the concentration range of 5-30 mg/L at lower temperature. The adsorption results at different temperature showed that the PNIPAAm/CS hydrogels adsorbed UO_2^(2+) ions at lower temperature. Thermodynamic parameters such as enthalpy change (ΔH), entropy change (ΔS), free energy change (ΔG) were determined. The negative values of ΔH and ΔS indicated that the spontaneous nature and exothermic process of the U (VI) adsorption. The increase in the value of ΔG with a rise in temperature showed that the sorption was more favorable to low temperature.

並列關鍵字

Thermo-sensitive ； hydrogel ； Inter-Penetrating Networks ； Uranium ； Adsorption