Clouding phenomena and thermodynamics of TX-100 + polyethylene glycol mixture: influence of several electrolytes

Abstract

Herein, the solution properties of Triton X-100 (TX-100) and polyethylene glycol (PEG) mixtures in H2O and salt (potassium, sodium, and ammonium) solutions have been observed through the cloud point (CP) detection technique. The present observation reveals that the values of CP of the TX-100 + PEG mixed solution, in the presence of different salts, undergo a decrease compared to the values found in H2O medium. The anion of common salts, such as sodium, potassium, and ammonium, was found to reduce the values of CP in the sample mixtures in the order: SO42− > Cl− > PO43−. The $$\Delta G_{{\text{c}}}^{0}$$ value was calculated as positive in all experimental cases, and this observation manifests a non-spontaneous nature of clouding system. The non-spontaneity of TX-100 + PEG clouding process was gradually declined with the enhancement of salt concentrations. The $$\Delta H_{{\text{c}}}^{0}$$ and $$\Delta S_{{\text{c}}}^{0}$$ values were found negative, which experience a decrease with the addition of more concentrated salt solutions in almost all of the cases studied. The negative values of $$\Delta H_{{\text{c}}}^{0}$$ and $$\Delta S_{{\text{c}}}^{0}$$ indicate the existence of exothermic interactions (hydrogen bonding and weak dipole–dipole forces) operating between TX-100 and PEG. A linear relationship was established between $$\Delta H_{{\text{c}}}^{0}$$ and $$\Delta S_{{\text{c}}}^{0}$$ with R2 values in the range of 0.9997–1.00.