高浓度钠盐体系中丁二酸溶解度的测定和关联

Measurement and Correlation of Solubilities of Succinic acid in High Sodium Salt Solution

丁二酸在发酵液中是以解离状态存在，在酸化结晶过程中形成高浓度的无机盐，会对丁二酸的溶解度产生作用，进而影响丁二酸的结晶收率。研究考察了高浓度钠盐体系中 pH 与温度对丁二酸溶解度的影响，结果表明：由于氯化钠争夺自由水分子，丁二酸的饱和溶解度随氯化钠浓度的增加而显著降低。在此基础上，分别测定了丁二酸在不同pH下的饱和溶解度，在277.2～333.2 K，丁二酸的饱和溶解度均随体系pH的降低而迅速下降，表明丁二酸解离状态及氯化钠的积累对丁二酸溶解度具有显著影响。同时采用Yaws模型对实验数据进行了关联，以温度和pH为变量，获得了相应的溶解度方程，其平均相对误差均小于3.0%，表明Yaws模型拟合得到的溶解度方程与实验值具有很好的相关性，可用于计算高浓度钠盐体系中丁二酸的溶解度数据。

Succinic acid is dissociated in fermentation broth, and inorganic salts with high concentration are formed in acidifying crystallization process, which could affect the succinic acid solubility and have influence over crystallization yield finally. The effects of pH and temperature on succinic acid solubility in high sodium salt solution were studied, the results show that free water molecules are attracted by sodium chloride and the saturated solubility of succinic acid decreases obviously with the increase of sodium chloride concentration in the solution. Based on above study, the saturated solubility of succinic acid at various pH were determined, the saturated solubility decreases with the decrease of pH at 277.2~333.2 K, which indicates that the dissociated state of succinic acid and accumulation of sodium chloride affect the solubility of succinic acid observably. The experiment data were also correlated with Yaws equation; using the temperature and pH as the independent variables, the solubility equations were derived. The average relative errors of the equation are lower than 3.0%, the results show that the solubility equation of Yaws mode could correlate experimental values well, which could estimate the succinic acid solubility in high sodium salt solution.