Preparation and characterization of acrylonitrile–butadiene–styrene/poly (vinyl acetate) membrane for CO 2 removal Hamidreza Sanaeepur a , Abtin Ebadi Amooghin b , Abdolreza Moghadassi c , Ali Kargari a,⇑ a Department of Petrochemical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Mahshahr Campus, Mahshahr, P.O. Box 415, Iran b Department of Chemical Engineering, Farahan Branch, Islamic Azad University, Farahan, Iran c Department of Chemical Engineering, Faculty of Engineering, Arak University, P.O. Box 38156-875, Arak, Iran article info Article history: Received 9 April 2011 Received in revised form 2 June 2011 Accepted 2 June 2011 Available online 23 June 2011 Keywords: Carbon dioxide separation Polymeric membrane ABS Poly vinyl acetate (PVAc) abstract CO 2 removal from different gas streams via the polymeric membranes has been propounded as an impor- tant issue in greenhouse gas emissions control, natural gas upgrading, and enhanced oil recovery. Here, polymeric blend membranes were prepared from acrylonitrile–butadiene–styrene (ABS) and poly vinyl acetate (PVAc), and their CO 2 /N 2 and CO 2 /CH 4 separation characteristics were investigated. The influence of different PVAc contents on gas separation performance and the effect of pressure, ranging from 1 to 8 bar, on CO 2 permeability were studied. Furthermore, the morphology of the membranes was analyzed by FTIR, XRD, DSC and SEM. It was shown that the highest CO 2 permeability of 5.72 Barrer for the mem- brane containing 10 wt.% PVAc, the highest CO 2 /CH 4 selectivity was 29 in 20 wt.% PVAc and CO 2 /N 2 was 40.41 in 30 wt.% PVAc contents. These results comprised from different effective factors such as PVAc ace- tate polar groups, compactness in polymer matrix at the presence of high molecular weight PVAc, and the acrylonitrile and flexible butadiene contents of ABS. Furthermore, in the transmembrane pressure of 2–8 bar the CO 2 permeability approximately descended with the pressure increase for PVAc content of 0–40 wt.%, and it ascended for 50–60 wt.%. Generally, the prepared membranes can be taken into account as better membranes for CO 2 /N 2 separation than CO 2 /CH 4 . Ó 2011 Elsevier B.V. All rights reserved. 1. Introduction In the past decades, membrane technology has been propounded as a favorite alternative for the conventional industrial processes such as chemical absorption, physical absorption, pressure swing adsorption, temperature swing adsorption, and cryogenic distillation. Due to the economical considerations and excellent operating conditions, membrane process has been considered as a viable method in industrial applications [1]. Polymeric membranes in gas separation have been noticed in many researches. Improvement of the membrane quality and per- formance (both high permeability and the capable selectivity) has been more noticeable. CO 2 removal from gas streams are taken into account as an important instance in industries; some examples are: CO 2 captur- ing from off-gas or flue gases for greenhouse gas emissions control (CO 2 /N 2 separation), natural gas upgrading, enhanced oil recovery, landfill gas recovery (CO 2 /CH 4 separation), etc. [2–6]. Poly vinyl acetate (PVAc) is an attractive cost-efficient, high- tonnage bulk commodity polymer [7]. Because of its low mechan- ical strength, PVAc cannot be used as an individual polymer in membrane fabrication. On the other hand, due to the existence of polar acetate groups in PVAc structure and the phase behavior of CO 2 exposed in PVAc (its structure varies in such a way that leads to a higher solubility of CO 2 with respect to the other vinyl hydro- carbon polymers), it could be a suitable option for CO 2 gas separa- tion membrane [8]. Therefore, it should be used in combination with the other polymers to form a copolymer. As a well-known example, copolymerization of PVAc with polyethylene forms ethyl- ene vinyl acetate (EVA). Because of its mechanical properties, chemical resistance, flexibility and processability, the EVA is ap- plied extensively in engineering and industrial fields [9,10]. Most approaches to VA containing copolymers are allocated to the preparation of the membranes which are utilized in liquid mix- ture separation. Pervaporation of ethyl acetate from aqueous solu- tion [11,12], methanol/MTBE [9], benzene/cyclohexane separation [13,14], and methyl substituted benzenes [10], are some of the ma- jor accomplished efforts. In recent years, some researchers have tried to prepare various types of VA containing gas separation membranes. Marais et al. [15,16], prepared an EVA/PVC blend membrane and investigated the O 2 , CO 2 and H 2 O permeabilities. They showed that the H 2 O/ CO 2 and H 2 O/O 2 selectivities increase by an increase in the vinyl acetate content. Mousavi et al. [17] studied the gas separation properties of ethylene vinyl acetate (EVA) membranes for 1383-5866/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.seppur.2011.06.003 ⇑ Corresponding author. Tel./fax: +98 21 66405847. E-mail addresses: Kargari@aut.ac.ir, Ali_Kargari@yahoo.com (A. Kargari). Separation and Purification Technology 80 (2011) 499–508 Contents lists available at ScienceDirect Separation and Purification Technology journal homepage: www.elsevier.com/locate/seppur