磷脂酰胆碱在硅胶上吸附特性的研究

摘要

为了研究硅胶对磷脂酰胆碱(PC)的吸附特性,通过分析不同吸附等温线和PC质量浓度随时间变化曲线,筛选出等温吸附模型和动力学模型并对其进行验证,求取了吸附热力学参数.结果表明:Langmuir等温吸附模型拟合结果良好,相关系数R2均在0.99以上,Lagergren拟一级动力学模型求出的平衡吸附量Qe更接近实验值.所以,这2种模型能更好地描述整个吸附过程,相对误差均在5％以内,可信度较高.此外,整个吸附过程主要受液膜扩散控制,热力学参数△H为-18.51--3.79 kJ/mol,该吸附为放热过程;△G恒负,吸附过程自发进行;△S在低浓度范围内恒负,高浓度范围内恒正,主要是PC与氯仿在硅胶吸附位点存在竞争关系所导致.%The adsorption property of silica gel on phosphatidylcholine (PC) was studied.By analyzing the different adsorption isotherms and the curves of PC mass concentration changed with time,the isothermal adsorption model and dynamic model were selected and proved.The thermodynamic parameters were obtained.The results show that the correlation index R2 of Langmuir isothermal adsorption model is more than 0.99 and the equilibrium absorption capacity Qe of Lagergren pseudo first order kinetics model is closer to experimental results.The two models were suitable for the adsorption process.The relative errors were verified to be less than 5％ and the reliability was higher.The whole adsorption reaction was controlled by liquid film diffusion.The value of △H was between -18.51--3.79 kJ/mol which showed that the adsorption was an exothermic process.The value of △G was less than zero that indicated the adsorption process was spontaneous.The value of △S in low concentration range was constant negative,but in the high concentration range it was constant positive.It was caused by the competition between PC and solvent chloroform on silica gel adsorption sites.