The Crystallization Process Of Taurine

Taurine is found to play an important role in the brain development of infants and children,but also recognized to have the effect on the antitumor activity,antioxidant activity,antihypertensive activity and nerve regulation.Due to the limited amount synthesized in human body,taurine is in big demand of the food additive market.At present,the domestic taurine,mainly manufactured through the cooling crystallization from water solution,has the disadvantages of low yield rate,caking and small particle size.In view of these problems,the research on the solution thermodynamics and kinetics of taurine was carried out,and finally a new crystallization process was proposed,with which the yield was raised and the quality of taurine crystals was greatly improved.The solubility of taurine in the binary water + acetone solvent mixture was measured at temperatures ranging from 278.15 K to 323.15 K using the laser monitoring technique,and the experimental data are well correlated by the mathematical model to form a solubility surface.The solubility of taurine decreased with both the increase of acetone mole fraction and the falling temperature.Thermodynamically,the acetone-water binary system is suitable for the combined cooling and anti-solvent crystallization of taurine.Next was the research on kinetics.The induction time and the metastable zone were exactly measured.The experimental results showed that two nucleation mechanisms exist in this system,homogeneous nucleation at high supersaturation and heterogeneous nucleation at low supersaturation.It was determined that the growth of taurine was controlled by the 2D and spiral growth models,which was verified by the surface topography obtained from the AFM.The widths of the metastable zone in different solvent composition were about 10? which was suitable for controlling of crystal growth in cooling crystallization process.Based on the results from thermodynamics and kinetics study,a combined cooling and anti-solvent crystallization process in binary acetone-water solvent mixture was put forward.According to the experimental growth rate function and metastable zone width,the optimal process condition was obtained.Compared to the traditional cooling process from water solution,the new combined process has the following advantages.The yield rate is raised from 73% to 96%,the caking of taurine crystals is reduced,the particle size is increased and the anti-solvent is easily recovered.