Thermodynamic properties of metamizol monohydrate in pure and binary solvents at temperatures from (283.15 to 313.15) K

Abstract The thermodynamic properties of metamizol monohydrate in pure solvents (methanol, ethanol, n-propanol and isopropanol) and two binary mixed solvent systems including (methanol + ethanol) and (methanol + isopropanol) were measured from 283.15 K to 313.15 K by gravimetric method under atmospheric pressure thought as 0.1 MPa. The modified Apelblat equation, the CNIBS/R-K equation, the Hybrid model and the NRTL model were used to correlate the solubility of metamizol monohydrate, respectively. The results show that the solubility of metamizol monohydrate in all the tested solvents increases with the rising temperature which means that it has temperature dependence. What's more, the effects of solvent components of the binary solvent mi x tures on solubility were discussed, it illustrates that the increasing of the molar fraction of methanol gives the system a greater dissolving power. Furthermore, according to the NRTL model, the enthalpy, the Gibbs energy and the entropy of the mixing process were also obtained and discussed.