To overcome low solubility of naproxen (NAP), deep eutectic solvents (DESs) based on choline chloride (ChCl) with glycerol (G) and oxalic acid (OA) as green solvents have been used up to 0.9 mole fraction of DES at T = (298.15 to 313.15) K.
DESs were prepared by combination of the two components with the molar ratios: ChCl/glycerol (1:2) and ChCl/oxalic acid (1:1). The solubility of NAP in the aqueous DESs solutions was measured at different temperatures with shake flask method.
The solubility in these solvents increased with increasing the weight fraction of DESs, especially in ChCl/OA. The solubility data were correlated by e-NRTL, Wilson and UNIQUAC models. Also, the thermodynamic functions, Gibbs energy, enthalpy, and entropy of dissolution were obtained.
Oxalic acid based DES exhibits higher solubility than glycerol based DES. The thermodynamic models were successfully used to correlate solubility data. In addition, the results show that, the main contribution for NAP solubility in the aqueous DES solutions is the enthalpy.