LAUSR

Scarce knowledge on the behavior of vitamins in aqueous solutions in the presence of additives is often a limiting factor for industrial applications such as process design and optimization. Knowing the pH-solubility profiles of vitamins is fundamental for understanding and controlling their behavior in aqueous solutions. In the present work, pH-dependent solubilities of the vitamins ascorbic acid (VC), riboflavin (VB2), nicotinic acid (VB3acid), folic acid (VB9), and cyanocobalamin (VB12) were measured at T=298.15 K and p=1 bar. These results were compared with the pH-solubility profiles obtained with modified Henderson-Hasselbalch equations using pKa values from the literature. Further, the solubilities of poorly soluble VB2, VB9, and VB12 were increased by the addition of covitamins VC, VB3acid, and nicotinamide (VB3amide). As observed, VB3amide increases the vitamin solubility much stronger than VC and VB3acid. These covitamins are called “hydrotropes” in several works of literature, and they increase...