Zn^(2+)改性丝光沸石对甲基橙的吸附性能研究

Methyl Orange Adsorption by Zn^(2+) Exchanged Mordenite

采用盐熔融法,将Zn2+交换丝光沸石分子筛制备Zn2+改性丝光沸石吸附材料。通过该材料对甲基橙的吸附动力学和吸附热力学研究,了解其吸附机理。研究结果表明:Zn2+改性丝光沸石对甲基橙的吸附动力学可用拟二级动力学方程来描述,计算值与试验值吻合较好,相关系数达到0.99;Zn2+改性丝光沸石对甲基橙的吸附等温线均符合Langmuir和Freundlich方程,室温下相关系数均大于0.9。根据不同温度下的热力学平衡常数,推算出Zn2+改性丝光沸石对甲基橙的吸附吉布斯自由能变ΔG0<0,吸附焓变ΔH0>0,表明吸附为自发的吸附过程,升温有利于吸附的进行,且吸附过程主要是物理吸附。

Zn2＋ exchanged mordenite was obtained by zinc ions exchanged with mordenite through salt melting procedure.The adsorption kinetics and thermodynamics of the methyl orange adsorption by Zn2＋ exchanged mordenite were studied to assess the adsorption mechanisms.The kinetics of Zn2＋ exchanged mordenite can be best described as pseudo-second order kinetics model.The adsorption capacity calculated by the model was consistent with the actual measurement,with the correlation coefficient higher than 0.99.The equilibrium data were analyzed by using the Langmuir and Freundlich model,which revealed that both Langmuir and Freundlich model were suitable to describe the methyl orange adsorption by Zn2＋ exchanged mordenite with the correlation coefficients higher than 0.9.According to the dependence of thermodynamic equilibrium constant on temperatures,the thermodynamic parameters associated with the adsorption process were calculated.The negative values of ΔG0 indicated that the overall adsorption processes were spontaneous.And the positive value of ΔH0 showed that the adsorption processes were endothermic in nature and the adsorption mechanisms were dominated by physical adsorption.