Abstract
The solubility of α-form and β-form l-glutamic acid (L-GA) in aqueous (NH4)2SO4 solutions with 0–1.50 molal (NH4)2SO4 was determined at 288.15 K. And the solubility in aqueous solutions and actual L-GA fermentation mother liquor (GAFML) without and with 0.75 molal (NH4)2SO4 was determined at temperatures ranging from 278.15 to 333.15 K. The results showed that for all the cases (NH4)2SO4 exhibited salting-in effects on L-GA, and the solubility of stable β-form was lower than that of metastable α-form. The other coexisting solutes together with (NH4)2SO4 in the GAFML jointly increased the L-GA solubility. Specifically, 0.75 molal (NH4)2SO4 aroused 19.0–83.0% of total solubility increment at the temperature range and polymorph studied. Based on the data obtained, the dissolution enthalpy and the entropy of L-GA were estimated by Van’t Hoff correlation. The solubility data were correlated using empirical three parameter Van’t Hoff equation. The model demonstrated good fitting with the experimental data.
Published Version
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