Liquid-liquid Equilibrium Of The Ternary System Of 3-mercaptopropionic Acid-trichloromethane-water

3-Mercaptopropionic acid(3-MA)is an important chemical intermediate and industrial raw material.It is an important chemical intermediate for the preparation of anti-depressant fenaruril.It is an important chemical raw material for the preparation of cross-linking agents,rust inhibitors,hardeners and resin additives.At present,the main synthesis method of 3-mercaptopropionic acid in industry is the sodium hydrosulfide process,which is obtained through the reaction of a mixture of 3-mercaptopropionic acid and water,and then extracted to obtain 3-mercaptopropionic acid with high purity.Based on this,the phase equilibrium of the 3-mercaptopropionic acid-water-chloroform ternary system was studied,and the influence of temperature and NaCl concentration on the phase equilibrium was discussed.The purpose is to improve basic data for preparing high-purity 3-mercaptopropionic acid with chloroform as the extractant.In the study,analytical methods for the determination of 3-mercaptopropionic acid and chloroform were first established,3-mercaptopropionic acid was determined by direct iodometric titration,and chloroform was determined by gas chromatography.The accuracy and accuracy of the above method were confirmed by the precision and recovery experiments.Then,the experimental equilibrium oscillation time and equilibrium standing time of the three-phase system were determined through experiments,and the 3-mercaptopropionic acid was purified by vacuum distillation.The concentration of 3-mercaptopropionic acid was purified from 99.18% to 99.91%,which can greatly improves the accuracy of the experimental results.The ternary liquid-liquid equilibrium data at 303.2K,313.2K,and 323.2K were measured in the experiment.The ternary phase diagram was plotted and it was found that as the temperature increases,the partition coefficient(D)and the selectivity coefficient(S)decreased,which indicating that high temperatures are not conducive to the extraction of the system.Then the liquid-liquid equilibrium data of 3-mercaptopropionic acid-watertrichloromethane system at three different temperatures were checked by the Hand equation and the Othmer-Tobias equation for consistency,and it was confirmed that the experimental results are reliable.Then the NRTL equation and the UNIQUAC equation are used to fit and predict the liquid-liquid equilibrium data at three different temperatures,and the binary interaction parameters of the system are obtained.The results show that the fit between the calculated and experimental values is closed,and the root mean square deviation is less than 0.0164.Moreover,the predicted value is closed to experimental values,and the root mean square deviation is less than 0.0337,which indicates that the NRTL equation and the UNIQUAC equation have good applicability to this system.Finally,the effects of different NaCl concentrations on the phase balance were investigated.The liquid-liquid equilibrium data of NaCl mass concentrations of 0%,2%,and 6% were measured by experiments.The ternary phase diagrams were plotted and the results show that as the mass concentration of NaCl increases.,D and S increase,indicating that the addition of NaCl to the system will facilitate the extraction of the system.The liquid-liquid equilibrium data at different NaCl mass concentrations were checked by the Hand equation and the Othmer-Tobias equation,and the experimental data were fitted using NRTL equations and UNIQUAC equations.