计量置换参数Z值分量的测定

摘要

以计量置换吸附理论(SDT-A)为基础,从理论上推导出计量吸附模型中表征溶质对固定相亲合势大小的参数βa值与流动相中强置换剂浓度的对数呈线性关系.计量置换模型中的参数n和q (n和q分别代表1摩尔溶剂化溶质被吸附时,从吸附剂表面和从溶质分子表面所释放出的溶剂的物质的量)是计量置换参数Z值的分量, 是两个非常有用的参数,可以从这个定量关系中直接获得.推导出的方程用苯的衍生物进行了实验验证, 获得了较满意的结果.将这种方法计算得到的分量值与SDT-A与计量置换保留模型(SDT-R)相结合的方法得到的分量值进行了比较, 发现两种方法所得到的分量值符合较好,且n和q都遵循同系物碳数规律.同时也发现当溶质在液-固表面吸附时,从吸附剂上释放出的溶剂分子要比从溶质表面释放出的溶剂分子多(n＞q).%Based on the stoichiometric displacement theory for adsorption (SDT-A) of solute, an equation expressing the linear relationship between the affinity of the solute to the adsorbent (βa), and the logarithm of the molar concentration of the solvent in bulk solution (log aD), was derived. The terms n and q values (moles of the solvent separately released from the adsorbent and solute as one mole of solute is adsorbed), that are the fractions of the stoichiometric parameter Z (Z=n+q), were obtained from this quantitative relationship. The derived equation was tested by the derivatives of benzene under different methanol concentrations by frontal analysis of reversed-phase liquid chromatography (RPLC) and satisfactory results were obtained. Moreover, the terms n and q were tested with the presented method, and also examined by the combination of the SDT-A with stoichiometric displacement theory for retention (SDT-R). Both n and q were further validated to follow the homologue rule. More moles of the solvent were released by the adsorbent than by the solute (n＞q) and the n value increases when the group attached to benzene was nonpolar.