To improve conversion of n-butanol to the corresponding ester using acetic acid, the ionic liquid 1-allyl-3-butylimidazolium bis(trifluoromethanesulfonyl) imide ([ABIM]TFSI), which does not dissolve in the water by-product, and poly(vinyl alcohol) (PVA) or PVA-TEOS (tetraethoxysilane) hybrid membranes were employed when using evapomeation (EV), along with microwave heating. The effect on the conversion of n-butanol of each individual process variable as well as that of all of the variables used in combination was investigated, and the characteristics of each approach are discussed. (c) 2012 Elsevier B.V. All rights reserved.