Kojic acid in fourteen mono-solvents: Solubility data, Hansen solubility parameter and thermodynamic properties

Highlights: • Solubility of kojic acid in fourteen pure solvents was measured. • The miscibility of kojic acid in solvents was revealed by Hansen solubility parameter. • Experimental solubility was discussed and correlated by five thermodynamic models. • The thermodynamic properties were evaluated by van't Hoff equation. 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-dioxane > 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 (Δ_disG^o, Δ_disH^o, Δ_disS^o) of kojic acid in investigated solvents were calculated by van't Hoff equation. The positive values of Δ_disH^o and Δ_disS^o indicated that the dissolution process of kojic acid in all the measured solvents was endothermic and entropy-driven.