Water activities of binary and ternary aqueous aluminium salts and poly(ethylene glycol) solutions at T=303.15 K: Experimental and correlation

In this study, water activity measurements by isopiestic method have been carried out on some aqueous electrolyte solutions of both binary aqueous systems (Al(NO3)(3), Al-2(SO4)(3) and AlCl3), ternary aqueous systems (polyethylene glycol + AlCl3 + water) and (polyethylene glycol + Al(NO3)(3) + water) at T = 303.15K. Furthermore, constant water activity curves, for ternary systems, have been plotted to study the salt effect. A relation between the salting-in effect of salt on the polymer aqueous solution and the slopes of constant water activity curves was reported. It was found that the slopes of constant water activity curves have a positive deviation from the linear isopiestic relation. In addition, the experimental water activity has been correlated successfully with some segment-based local composition models such as Wilson model, Non-Random Two Liquid (NRTL) model and the segment-based Non-Random Factor (NRF) model. The agreement between the correlation and the experimental data is good. (C) 2015 Elsevier B.V. All rights reserved.