Measurement and correlation of solubilities of succinic acid in high sodium salt solution

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.