Different from enhancing permseleclivity of calion exchange membrane (CEM) by he common surface modification, this study reports an annealing treatment strategy to enhance the density of PVA-based CEM by tuning crystallinity, which can improve pore-size sieving effect for ions. X-ray diffraction (XRD) suggests that these membranes possess controllable crystallinity ranging from 11.8% to 43.9%. AFM analysis implies that after annealing treatment crystalline regions increase remarkably and distribute uniformly in membrane. When they are applied to electrodialysis (ED) for acid recovery from H+/Zn2+ solution, it is experimentally evidenced that the permselectivity (P-H+(Zn2+)) and Zn2+ leakage are dependent on crystallinity. The optimal membrane with a crystallinity 43.9% exhibits a favorable permselectivity of 0.007 between Zn2+ and H+ and only 0.01% of Zn2+ leakage, which are better than that of monovalent cation exchange membrane modified by surface modification. (C) 2014 Elsevier B.V. All rights reserved