HUANG Yang, WANG Fan-fei, WANG Wei-qing, FENG Qi-ming, DONG Fa-qin
(Key Laboratory of Solid Waste Treatment and Resource Recycle, Ministry of Education, Mianyang 621010, China)

Abstract: Ion exchange thermodynamics of NH4+-clinoptilolite exchange of Zn2+ and Ag+ were studied by liquid-phase ionexchange in this paper. The ion exchange isotherm for NH4+-clinoptilolite exchange of Zn2+ and Ag+ was plotted. The selective correction coefficient Kc and the exchange equilibrium constant Ka for NH4+-clinoptilolite exchange of Zn2+ and Ag+ were calculated at exchange equilibrium under different conditions. The linear relation between lnKa and 1/T was elicited. The reaction normal mole enthalpy change ΔrHθm, the reaction normal mole Gibbs free energy change ΔrGθm and the reaction normal mole entropy change ΔrSθm were derived．Results show that the maximum ion exchange degree of NH4+-clinoptilolite exchange of Zn2+ and Ag+ are 0.668 and 0.856 with ΔrHθm of 7.165 kJ/mol and 5.276 kJ/mol, respectively, and ΔrGθm＜0, ΔrSθm＞0. It indicates that the ion exchange process is an endothermic and entropic increasing reaction. NH4+-clinoptilolite exchange of Zn2+ and Ag+ occurs spontaneously at 20 ℃ and increases with increasing temperature. Under the same conditions, the exchange capacity between NH4+-clinoptilolite and three kinds of antibacterial metal ions is Ag+＞Zn2+.

Keywords: Clinoptilolite; Metal ion antibacterial agent; Ion exchange thermodynamics

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ACTA MINERALOGICA SINICA Vol. 35, No. 3, 2015, Page 331-336