Liquid–liquid equilibria of hydrophilic alcohol + sodium hydroxide + water systems: Experimental and correlation

Binodal data for ethanol, 2-propanol and 1-propanol + sodium hydroxide (NaOH) + water systems were experimentally determined at 283.15, 298.15 and 313.15 K, respectively. An empirical equation was used to correlate the binodal data. On the basis of the empirical equation with binodal data and the lever rule, the tie-lines data for the investigated systems at 298.15 K were obtained via the MATLAB and then correlated by Othmer-Tobias and Bancroft equations. Temperature and salting-out effects on this type of ATPS were investigated. It was found that an increase in temperature leads to an expansion of the two-phase area. The salting-out ability of NaF is stronger than that of NaOH. Additionally, the phase-forming abilities of the investigated hydrophilic alcohols were discussed by both the effective excluded volume (EEV) of the investigated salt and the location of the binodal curves of the investigated systems. The phase-forming abilities of the investigated hydrophilic alcohols follow the order: 1-propanol > 2-propanol > ethanol.