Several Solid Solubility Using Laser Monitoring Technique

The solubility data are essential for designing chemical and pharmaceutical industry processes, such as crystallization and liquid extraction processes, and conducting further thermodynamic research. Hench, solubility data of solids in different solvents at various temperatures are quite necessary and important.Experimental data containing the solubility of gallic acid in water and binary mixtures of ethanol+water, the solubility of3,4,5-trimethoxybenzoic acid in ten monosolvents of ethanol,1-propanol,2-propanol,1-butanol,2-methyl-1-propanol, methyl acetate, ethyl acetate, butyl acetate, acetone and2-butanone and binary mixtures of ethanol+1-butanol and1-butanol+ethyl acetate, the solubility of veratric acid in eight monsolvents of ethanol,1-propanol,2-propanol,1-butanol,2-methyl-1-propanol, methyl acetate, ethyl acetate and2-butanone and binary mixtures of ethanol+1-butanol.The solubility curves of solutes in different solvents are obtained and the mixed effects of solbility in binary mixtures are analyzed. The rate of logarithm of solubility vesus with temperature is defined to measure the influence of temperature in crystallization process.The Apelblat equation, NRTL equation, and UNIQUAC equation are employed to correlate the solubility of3,4,5-trimethoxybenzoic acid and veratric acid in monosolvents, respectively. The Apelblat equation can give the best correlation.The Apelblat equation and Jouyban-Acree model are employed to correlate the solubility of gallic acid in binary mixtures of ethanol+water and the solubility of veratric acid in binary mixtures of ethanol+1-butanol. A modified Jouyban-Acree model trained with solubility data of veratric acid in binary mixtures at two temperatures, is used to calculate the solubility at other temperatures, the relative average deviation is3.84%.UNIFAC and modified UNIFAC models are used to predict the solubility of3,4,5-trimethoxybenzoic acid and veratric acid in monosolvents, the relative average deviations of UNIFAC model for two solutes is37.92%and24.87%, respectively, the the relative average deviations of modified UNIFAC model for two solutes is60.52%and31.72%. The group of (CH3O)r is new defined, and the binary model parameters of this new group with other group are regeressed by experimental solubility data in this work.NRTL-SAC model is trained with solubility of3,4,5-trimethoxybenzoic acid and veratric acid in four selected monosolvents to predict the solubility data in other monosolvents and binary mixtures. The averation deviations of NRTL-SAC model for two solutes are48.97%and4.24%, respectively. While, NRTL-SAC model can correctly reflect the solubility changing with the changing of mixture solvents components.