Study On Crystallization Process Of Veramoss

Veramoss is a kind of important fixative(AA is used instead of the veramoss),deodorant and base fragrant in fragrances,which has been widely used in soap,detergent and other high-grade perfume flavor,which has very high economic value.However,there are still some problems in the process of AA production at present,such as unstable quality and low purity.In order to solve these problems,the crystallization thermodynamics and kinetics,crystallization process of AA were investigated,and the optimized parameters for the purification of AA were obtained.The solubility of AA in n-butanol,ethanol,isopropyl alcohol,ethyl acetate,acetone,tetrahydrofuran,isoamyl alcohol,amyl alcohol,propanol,DMF and different composition of ethanol in water system was measured by dynamic method,the modified Van~'t Hoff equation,CNIBS/R model and the Apelblat model were successfully used to correlate the experimental solubility,and all of the models provided good fitness to the data,the correlation coefficient is greater than 0.99.Furthermore,the thermodynamic parameters(dissolving enthalpy,dissolving entropy and Gibbs free energy)of AA in different solvents were also calculated based on the Wilson equation and experimental solubility data,the dissolving process of veramoss in all experimental pure solvents were observed as an endothermic,non-spontaneous and an entropy-driven process,and in the binary solvent mixtures of{ethanol+water}were observed as an endothermic,spontaneous and an entropy-driven process.The solubility and metastable zone of ethyl ester in methanol were also measured.Dilution and cooling crystallization of AA was analyzed by the method of moment transformation with batch dynamic method.The growth of AA crystal in the studied system belongs to the size dependent growth,the ASL and MJ2size-dependent model were chosen to deal with the experimental data,and the experimental data were analyzed by multiple linear regressions by least squares to get the nucleation rate and growth rate equations.In addition,the effects of super saturation,stirring intensity and suspension density on the crystallization kinetics of AA were discussed.Based on the study of the thermodynamics and kinetics of the crystallization,the experimental conditions of the crystallization process were explored and optimized.The effects of various parameters on the crystallization process were investigated,such as the crystallization temperature,cooling rate,rotational speed,washing,the initial concentration of the crystallization solution,the rate of flow rate,the amount of flow and the optimal process parameters were determined.This paper provides a useful reference for the crystallization process of AA.