THERMODYNAMIC STUDY ON ION EXCHANGE DURING PREPARING Cu²⁺-CLINOPTILOLITE ANTIMICROBIAL AGENT

The Cu-clinoptilolite was prepared by liquidphase ion exchange,and the corresponding value of C/Co and q/Q in the exchange liquor and clinoptilolite phase was calculated according the measured Cu²⁺ concentration while reaching exchange equilibrium under different temperature and primary Cu²⁺ concentration,the ion exchange isotherm was plotted according above data.Further,the corrected selectivity coefficient Kc and the exchange equilibrium constant Ka was also calculated,and the linear relation was educed between lnKα and 1/T.On the basis,enthalpy change Δ_rH^θ_m,Gibbs free energy Δ_rG^θ_m and entropy changes Δ_rS^θ_m were figured out.The researching results show Δ_rH^θ_m=7.101KJ/mol、Δ_rG^θ_m<0、Δ_rS^θ_m>0,these illustrates the ion exchange process is an endothermic and entropy increase reaction;ion exchange can occur automatically under different experimentation temperature,but increasing temperature is advantageous to Cu²⁺ exchange.