Toward Thermodynamic Predictions of Aqueous Vitamin Solubility: An Activity Coefficient-Based Approach

Research on water-soluble vitamins is still required, especially due to the diversity of their structures that influence strongly physicochemical properties of water–vitamin mixtures. Such influences are still underexplored. Further, solubility of vitamins in aqueous environment is of crucial importance for life sciences and process design, but still experimental data of vitamin solubility is rather limited in literature. In this work, solubilities of the vitamins ascorbic acid, riboflavin, nicotinic acid, folic acid, and cyanocobalamin were predicted with Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT). PC-SAFT parameters for vitamins were estimated by fitting them to solubility-independent data, namely experimental liquid-density data and osmotic-coefficient data of aqueous vitamin solutions measured in this work. PC-SAFT predicted solubilities were validated by new experimental solubility data at T = 298.15 K and p = 1 bar. PC-SAFT predictions were in quantitative agreement to experimental vitamin solubility in water. Further, PC-SAFT allowed predicting the temperature influence on the solubility of vitamins in water with reasonable accuracy.