硅胶自环己烷中吸附含氧芳香化合物的研究

测定了15℃和30℃时硅胶自环己烷中吸附苯甲醇、苯甲醚、苯甲醛和苯甲酸的吸附等温线,这些等温线皆可用Langmuir公式表示。利用Langmuir常数n_m^s和b值计算了吸附过程的△G⁰、△H⁰和△S⁰;四种化合物的△S⁰皆为正值。测定了在较大复盖度时红外光谱图上硅胶表面自由羟基峰的移动值△v_OH。结果表明△H⁰和△v_OH及△v_OH^1/2间有线性关系。文中对所得结果做了初步的解释。

The Adsorption of Oxy-Aromatic Compounds from Cyclohexane onto Silica Gel

The adsorption isotherms for benzyl alcohol, anisole, benzaldehyde and benzoic acid on silica gel from cyclohexane have been measured at 15℃ and 30℃. The standard changes of free energy △G°, enthalpy △H° and entropy △S° in adsorption processes have been calculated from the Langmuir parameters. The results indicate that △S° is all positive. The shifts △VOHof the adsorption band of the stretching frequency of free hydroxyl groups on silica gel at high surface coverages were determined. The results show that △H⁰ is linear function of △v_OHor △v_OH^1/2.