基于拉曼光谱结合角度转换的安息香结晶热力学研究  

Thermodynamics of benzoin crystallization based on the Raman spectra combined angle conversion

作　　者：马鑫 刘安民 姚志湘[1] MAXin;LIU Anmin;YAO Zhixiang(School of Biological and Chemical Engineering,Guangxi University of Science and Technology,Liuzhou 545006,China)

机构地区：[1]广西科技大学生物与化学工程学院,广西柳州545006

出　　处：《广西科技大学学报》2023年第4期124-130,共7页Journal of Guangxi University of Science and Technology

基　　金：广西自然科学基金项目(2015GXNSFAA139038);广西重点研发计划项目(桂科AB16380348)资助。

摘　　要：采用拉曼光谱结合角度转换算法,建立安息香质量浓度与角度值的曲线方程,在热力学温度为273.15~343.15 K范围内,通过静置法与直接目测法观察安息香在95%乙醇中的饱和温度,测得的光谱数据经角度转换得到一系列角度值,由关联方程直接得出饱和溶解度与过饱和溶解度,用修正的Apelblat方程对溶解度数据进行关联,绘制介稳区,并通过van't Hoff模型以及Gibbs-Heimholtz方程计算相关溶解热力学数据。结果表明:建立的模型方程相关系数r为0.9959,验证模型相对误差在-4.29%~3.37%。Apelblat方程拟合的溶解度曲线相关系数r分别为0.9991及0.9990,安息香在95%乙醇溶液中的溶解度与过饱和溶解度随着温度的升高而增大,而介稳区宽度随着温度的升高而减小。计算得到安息香晶体溶解过程中的溶解焓为47.32 kJ/mol,结晶焓为-47.32 kJ/mol,溶解熵为173.63 J(/mol·K),吉布斯自由能为-6.18 kJ/mol,其溶解过程是一个随着温度升高而自发进行的吸热过程。与目前常用的重量法求溶解度相比,该方法简便快捷,通过采集不同温度下的安息香拉曼光谱,就能直接计算出安息香的浓度,可以用于多种体系的热力学分析研究。The curve equation of benzoin concentration and angle value was established by using Raman spectroscopy combined angle conversion algorithm.The saturation temperature of benzoin in 95%ethanol was observed at T=273.15~343.15 K by the static method and the direct-vision method.The measured spectral data was angle-converted to obtain a series of angular values,and the saturation solubility was directly obtained from the standard curve equation.The solubility data were correlated with the modified Apelblat equation,the metastable zone was plotted,and the relevant dissolution thermodynamic data were calculated by the van't Hoff model as well as the Gibbs-Heimholtz equation.The results show that the correlation coefficient of the established model equation was 0.9959,and the relative error of the verified sample was between-4.29%and 3.37%.The solubility curve correlation coefficient r of the Apelblat equation fit was 0.9991 and 0.9990,the solubility and supersaturated solubility of benzoin in 95%ethanol increased with increasing temperature,while the width of the metastable zone decreased with increasing temperature.During the dissolution of benzoin crystals,the dissolution enthalpy was 47.32 kJ/mol,the crystals enthalpy was-47.32 kJ/mol,the dissolution entropy was 173.63 J/(mol·K),Gibbs free energy was-6.18 kJ/mol,so the dissolution process was a spontaneous endothermic reaction with increasing temperature.Compared with the commonly used weight method to obtain the solubility,this method is simple and fast.Therefore,the concentration of benzoin can be directly calculated by collecting the benzoin Raman spectra at different temperatures,which can be used for the thermodynamic analysis of various systems.

关 键 词：安息香 结晶热力学 溶解度 过饱和溶解度 介稳区 

分 类 号：TQ651.2[化学工程—精细化工] R284.1[医药卫生—中药学]