Equilibrium study and diversified models of drug Norfloxacin in eight pure organic and binary solvents at T = (278.15–328.15) K

Research on relevant solid–liquid equilibrium of drug Norfloxacin (NFLX) in different solvents is necessary for an elementary study of industrial implantation. In this work, the solid–liquid equilibrium of NFLX in ethanol, 1-butanol, isopropanol, acetone, acetonitrile, ethyl acetate, N-hexane, N,N-dimethylformamide single pure solvent and in (N,N-dimethylformamide + ethyl acetate) binary solvent mixtures were probed under atmosphere pressure at desired temperatures from 278.15 K to 328.15 K. The Gibbs energy, enthalpy, and entropy of solution were obtained from these solubility data. The modified Apelblat model, the Buchowski–Ksiazaczak λh model, Redich-Kister (CNIBS/R-K) model, Jouyban-Acree model, ideal model and the Van't Hoff analysis were applied to depict and forecast the diversification tendency of solubility. The satisfactory simulation results were obtained. Moreover, the thermodynamic functions for NFLX dissolution from calculation, using the van't Hoff and Gibbs equations, imply that in each studied solvent and in binary solvent mixtures, the process of NFLX dissolution is endothermic. Based on the above analysis, N,N-dimethylformamide is checked as the best solvent and ethyl acetate can be used as an effective anti-solvent in the crystallization process of NFLX.