An aqueous solution is obtained as permeate through a polyimide membrane from a 1-hexanol/water biphase mixture with higher aqueous fraction than 0.52 under conditions of 0.15 MPa of pressure and 40 degrees C. Continuous separation of the aqueous phase from the mixture can be performed at 0.6 of aqueous fraction and 0.15 MPa, and a stable aqueous phase flux of 5.39 x 10(-8) m(3).m(-2) s(-1) obtained.