Journal of Membrane Science 343 (2009) 53–61 Contents lists available at ScienceDirect Journal of Membrane Science journal homepage: www.elsevier.com/locate/memsci Poly(vinyl alcohol)/polyelectrolyte complex blend membrane for pervaporation dehydration of isopropanol Qiang Zhao, Jinwen Qian ∗ , Quanfu An, Meihua Zhu, Minjie Yin, Zhiwei Sun Department of Polymer Science and Engineering, Key Laboratory of Macromolecule Synthesis and Functionalization (Ministry of Education), Zhejiang University, Hangzhou 310027, China article info Article history: Received 9 April 2009 Received in revised form 6 July 2009 Accepted 7 July 2009 Available online 14 July 2009 Keywords: PVA Pervaporation Isopropanol dehydration Blend membrane Polyelectrolyte complex abstract Poly(vinyl alcohol) (PVA) was blended with soluble polyelectrolyte complex (PEC) made from poly(diallyldimethylammonium chloride) (PDDA) and sodium carboxymethyl cellulose (CMCNa). Crys- tallinity, thermal transition, and thermal stability of the PVA/PEC blends were characterized by using wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and thermal gravity anal- ysis (TGA), respectively. Surface morphology, cross-section and phase structure of the blend membranes were examined by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Surface hydrophilicity and swelling behavior of the blend membranes were examined by water contact angle (CA) and swelling tests. Blend membranes were subjected to isopropanol dehydration, and effects of blend composition, feed composition and feed temperature on pervaporation performance are discussed in terms of phase structures of blend membranes. A performance of J = 1.35 kg/m 2 h, ˛ = 1002, was obtained for blend membrane containing 50 wt% PEC in dehydrating 10 wt% water–isopropanol at 70 ◦ C. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Membrane technologies are gaining increasing interest from both the scientific and applied points of view [1], and membrane separation is one of the most studied membrane technologies [2]. Gas separation [3,4], ultra-filtration [5–8], nano-filtration [9], reverse osmosis [10], membrane distillation [11], and per- vaporation [12–14] constitute the main scope of membrane separations. Membrane materials are of crucial importance for success- ful membrane separation technologies. Poly(vinyl alcohol) (PVA) is one of the most studied membrane materials due to its out- standing membrane forming ability, easy processing and abundant availability [15]. PVA membranes have been utilized in enzyme immobilization [16,17], gas separation [18], fuel cells [19] and pervaporation dehydration of organics [20–29]. However, due to the semi-crystalline character of PVA, permeation flux of PVA membranes in pervaporation dehydration is not satisfied. Strate- gies such as polymer blending [30,31] and organic–inorganic hybridization [32–37] were adopted to overcome this problem. Jiang and co-workers [38–40] designed a series of graphite ∗ Corresponding author. Tel.: +86 0571 87953780. E-mail address: qianjw@zju.edu.cn (J.W. Qian). filled PVA membranes and utilized them in separating ben- zene/cyclohexane mixtures and dehydrating organics. Huang and co-workers [41] blended chitosan with PVA and the membranes showed improved permeation flux. Aminabhavi and co-workers [42–45] blended poly(methyl methacrylate), sodium alginate and polyaniline with PVA and the selectivity of the blend membranes was improved as compared with pristine PVA membranes. These studies revealed useful illuminations on improving the pervapo- ration performance of PVA membranes. However, it is still quite necessary to further improve the permeation flux of PVA mem- branes. Recently, we reported a new method for fabricating novel homogeneous polyelectrolyte complex (PEC) membranes, whose permeation flux in organics dehydration was very promising [46–49]. These PEC membranes are composed of needle-shaped polyelectrolyte complex aggregates (PEC aggregates) and there are hydroxyl groups on these PEC aggregates. Hydrogen bond interactions should exist between PVA and PEC, due to which PVA is compatible with PEC. Hence, it is expected that the crys- tallinity of PVA membrane can be reduced, resulting in a lower mass transfer toward water and consequently higher fluxes. In this work, PVA was blended with soluble PEC to improve the pervaporation performance of PVA membranes. The relationship between structural characters of the PVA/PEC blend membranes and their pervaporation performances is also within the scope of this work. 0376-7388/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.memsci.2009.07.009