硅胶自水溶液中吸附丙酸和丁酸的计量置换吸附模型

Stoichiometric Displacement Model for the Adsorption of Propionic Acid and n-Butyric Acid by Silica Gel from Aqueous Solution

实验研究了硅胶在293、303和313K下,从水溶液中对丙酸和丁酸的吸附.发现该吸附服从液-固吸附中的计量置换吸附模型(SDM-A).根据吸附模型的线性参数研究了吸附热力学和吸附机理.该吸附是一个自发的、放热的熵减少过程.丁酸的标准吸附自由能比丙酸大,而标准吸附焓比丙酸小.推导出了实验条件下吸附自由能变化的计算公式.

The adsorption of propionic acid and n butyric acid from aqueous solution by silica gel has been studied at 293,303 and 313 K respectively.It was found that the adsorption obey stoichoimetric displacement model for adsorption at liquid solid system (SDM A). The thermodynamics and mechanism of adsorption processes were studied on the basis of linear parameter from SDM A. The adsorption is a spontaneous, exothermic process of reduced entropy. Standard free energy change for the adsorption of n butyric acid is larger than that of propionic acid. Standard enthalpy change for the adsorption of n butyric acid is smaller than that of propionic acid. The equation of free energy change for adsorption was derived.