Aqueous nicotine solutions: pH-measurements and salting-out effects - Analysis of the effective Gibbs energies of hydration and ionic strengths of the solutions

Abstract

This work is a continuation of previous studies on phase demixing - salting-out effects in aqueous nicotine solutions. Thus, pH measurements were performed, allowing a brief analysis of the existing hydrogen bond interactions. Salting-out effects the related experimental cloud point shifts provoked by the addition of two inorganic salts, potassium nitrate and sodium sulfate, which have not hitherto been studied, were determined. Analysis of the current and previously reported salting-out/or salting-in phenomena in nicotine aqueous solutions was performed. In this respect, five studied salts were included: four inorganic salts (sodium chloride, potassium nitrate, sodium sulfate and trisodium phosphate (Na3PO4)), and ionic the liquid 1-ethyl-3-methylimidazolium ethyl sulfate ([C(2)mim][EtSO4], commercial name ECOENG212 (R)). Based on pH measurements, the effective Gibbs energies of hydration and the ionic strengths of the respective ternary solutions were calculated and plotted against the related cloud-point shifts caused by the addition of the salts. For the studied salts, the results and diagram obtained within this work may be used to predict the cloud-points shifts, based on the related quantities of the salts added and/or the molar Gibbs energies of hydration and/or ionic strengths requested in each case.