Solubility Equilibrium And Model Association Of Trehalose And L-arabinose In The Binary Solvent System

Solubility data was the key basis for design and development of crystallization process, and the crystal form had important influence on solubility behavior of crystal in solution. In this paper, the solubility behavior of trehalose and L-arabinose in the binary solvent system were studied in details, it would provide basic data for industrial production of crystal. Firstly, based on our research about the solubility behavior and crystal transformation of trehalose in water + ethanol solvent system, the solubility data of trehalose in water + methanol solvent system were determined using gravimeter measurement, which methanol was chosen as anti-solvent. A dihydrate trehalose with different crystal habits had been found, which showed the white flocculent suspension in the mixed solvent, and the mole fraction of the critical water content ranged from 0.160 to 0.250. By means of differential scanning calorimetry(DSC) and X-ray diffraction(XRD), the two kinds of crystals were collected and measured to prove the difference of crystal habits for trehalose in water + methanol solvent system. In addition, the same measurement method was used to determine the solubility of L-arabinose in water + methanol solvent system, at temperatures from(283.15 to 308.15) K, while it had not appear the phenomenon of the crystal transformation in the system. There were obvious changes in the solubility data of the two materials in this paper with changing the temperature or the mole fraction of water, so cooling crystallization process, solventing-out crystallization process, cooling and solventing-out crystallization process could be used for purification of trehalose and L-arabinose.All of solubility data of trehalose and L-arabinose were fitted with six thermodynamic models, which were van’t Hoff model, modified Apelblat model, Jouyban-Acree model, Yalkowsky model, the combination version of the van’t Hoff and Jouyban-Acree models(J-A-V model), the combination version of the Apelblat model and Jouyban-Acree models(J-A-A model) respectively. Error analysis showed that the Apelblat model was the lowest deviation of the experimental value with the theoretical value for the two materials. Comprehensive consideration on the average relative deviation(ARD) values and the number of model parameters, the best fitted model was J-A-V model. In addition, the solubility data of trehalose lower and higher than the critical points were correlated by J-A-V model separately, due to the different crystal habits. The ARD values for the solubility data below and above the critical points were 0.187 and 0.151 respectively, which showed the model correlated the data well.