Liquid–liquid equilibrium and critical states for the system acetic acid + n-butanol + n-butyl acetate + water at 308.15 K

•LLE tie-lines and critical states of LLE for acetic acid–n-butanol–n-butyl acetate–water quaternary system at 308.15 K have been determined.•The LLE data for three ternary sub-systems with miscibility gap are presented.•The LLE data have been correlated by using NRTL model.

Liquid–liquid equilibrium (LLE) for the quaternary system acetic acid–n-butanol–n-butyl acetate–water and for the ternary sub-systems acetic acid–n-butyl acetate–water, n-butanol–n-butyl acetate–water and acetic acid–n-butanol–water were studied at 308.15 K and atmospheric pressure. Binodal surface and curves, tie-lines and compositions of critical points of LLE were determined. Experimental LLE data were correlated by NRTL model. Experimental LLE data were compared with the values calculated by NRTL models, these data are in good agreement.