Thermodynamic Study On The Solid-liquid Phase Equilibrium Of ?-Alanine In Pure And Binary Solvent Systems

As a kind of amino acid with important application value in the field of food and medicine,?-alanine has attracted numerous researchers to study its thermodynamic of solid-liquid phase equilibrium in different solvent systems.Solubility was significant in the process of studying the solid-liquid equilibrium of substances.However,most of the existing solubility data of ?-alanine were determined at constant temperature,which were lack of temperature-dependent data and insufficient for the design of the crystallization process ?-alanine.Consequently,this work aimed at measuring the ?-alanine solubility in different pure and binary solvents systematically.The solubility of ?-alanine in twelve neat solvents(water,methanol,ethanol,1-propanol,1-butanol,1-pentanol,2-methyl-1-propanol,2-propanol,2-butanol,acetonitrile,acetone,and ethyl acetate)and five binary mixed solvent systems(water + methanol,water + ethanol,water + 1-propanol,water + isopropanol,and water + acetone)were determined within the temperature range from 283.15 to 323.15 K under atmospheric pressure in this work.It can be concluded from the experimental results that the solubility value of ?-alanine increased with increasing temperature in neat solvents and binary mixed solvent systems which at a fixed solvent composition.The solubility of ?-alanine increased with the mole fraction of water in five binary systems at a certain temperature.The order of ?-alanine solubility in the selected twelve pure solvents was water > 1-butanol > methanol ? 2-butanol > 2-methyl-1-propanol ? 1-pentanol ? 1-propanol ? ethanol > 2-propanol > ethyl acetate > acetonitrile > acetone,the solubility of ?-alanine in polar protic solvents was higher than that in polar aprotic solvents.The solubility of ?-alanine was mathematically represented by the modified Apelblat,Jouyban-Acree,and Apelblat-Jouyban-Acree models,the corresponding results all showed good agreements,it illustrated three models in this work can be used to predict the solubility of ?-alanine.In order to analyze how the solvent effect affects the solid-liquid equilibrium of ?-alanine in pure solvents,the solubility of ?-alanine in twelve neat solvents was analyzed by multiple linear regression analysis with KAT-LSER model on the conditions of temperature of 293.15 K in this work,the fitting results demonstrated that the solubility of ?-alanine was affected by the solvent-solvent interaction of pure solvents principally.This work could provide basic solid-liquid phase equilibrium data for the crystallization and purification process of ?-alanine in industry.