Impacts of several salts on the clouding development, nature of interactions and associated physico-chemical variables of mixture of promethazine hydrochloride and conventional nonionic surfactant

Abstract

Herein, in the presence of electrolytes, the cloud points (CPs) of the mixture of a conventional uncharged amphiphile (triton X-100 (TX-100)) and promethazine hydrochloride (PMH; phenothiazine medicine) were measured and explained in great details. The CP values of the employed surfactant + PMH system were reduced with enhancing salts contents (NaCl, Na2SO4, NH4Cl, and (NH4)2SO4)), while the CP values of the study system followed the trend: Na2SO4 < NaCl and (NH4)2SO4 < NH4Cl. The different thermodynamic parameters of phase separation, including standard free energy (ΔG 0 c), enthalpy (ΔH 0 c), and entropy (ΔS 0 c) changes were also calculated and discussed elaborately. The values of free energy change (ΔG 0 c) were obtained to be positive, indicating that the clouding phenomena are non-spontaneous. Different transfer properties (free energy (ΔG 0 c.t), enthalpy (ΔH 0 c,t ), and entropy (ΔS 0 c,t ) of transfer), intrinsic enthalpy gain (ΔH 0,*c) and compensation temperature (T c) of the inspected system have also been assessed and discussed.