Kojic Acid in Fourteen Mono-Solvents: Solubility Data, Hansen Solubility Parameter and Thermodynamic Properties

In this research, solubility of kojic acid in fourteen mono-solvents was obtained by laser monitoring approach at various temperatures under 0.1 MPa. The mole solubility of kojic acid exhibited a positive relation with temperature. Moreover, the solubility sequence of kojic acid at 298.15 K is: dimethyl sulfoxide (DMSO) > N-methylpyrrolidone (NMP) > N, N-dimethylacetamide (DMAC) > N, N-dimethylformamide (DMF) > 2-methoxyethanol > 2-ethoxyethanol > acetic acid > methanol > 1,4-diox ane > ethanol > water > n-propanol > acetone > ethyl acetate. The Hansen solubility parameter (HSP) and solvents polarity were applied to explore this solubility behaviour. The experimental solubility data was correlated with five thermodynamic models including two-Suffix Margules, NRTL-SAC, NRTL, modified Apelblat equation and UNIQUAC model, and the calculated results indicated that all of models had great fitting effects with the measured solubility data. Furthermore, the solution thermodynamic properties (Delta(dis)G degrees, Delta H-dis degrees, Delta S-dis degrees) of kojic acid in investigated solvents were calculated by van't Hoff equation. The positive values of Delta H-dis degrees and Delta S-dis degrees indicated that the dissolution process of kojic acid in all the measured solvents was endothermic and entropy-driven. (C) 2020 Elsevier Ltd.