Synthesis, characterization and desalination study of novel PSAB and mPSAB blend membranes with Polysulfone (PSf) Mahesh Padaki a , Arun M. Isloor a, ⁎, Ahmad Fauzi Ismail b , M.S. Abdullah b a Membrane Technology Laboratory, Chemistry Department, National Institute of Technology-Karnataka, Surathkal, Mangalore 575 025, India b Advanced Membrane Research Center (AMTEC), Universiti Teknologi Malaysia, 81310 UTM, Skudai, Johor, Malaysia abstract article info Article history: Received 18 December 2011 Received in revised form 21 February 2012 Accepted 12 March 2012 Available online 10 May 2012 Keywords: NF membrane PSAB Desalination DIPS method The present paper describes the synthesis of poly sulphonyl amino benzamide (PSAB) and methyalated poly sulphonyl amino benzamide (mPSAB) polymer, using terephthalic acid chloride and substituted 4-amino- 1-benzensulphonmide in N-methyl-2-pyrrolidone. Polymers were characterized by FT-IR, NMR and GPC. Polysulfone composite membranes were prepared using these novel poymers by DIPS (Diffusion Induced Phase Seperation) method. These composite membranes are useful for water purification with special emphasis on sea water desalination. Newly prepared membranes were studied for salt rejection, water flux, molecular weight cut off by PEG solution, effect of the pH on water swelling and salt rejection and flux decline was also studied. 30 to 70% of the salt rejection was observed in all membranes. Effect of the dilution on salt rejection was studied using different concentration of NaCl solution varying from 1000 ppm to 3500 ppm. All the membranes showed 80% rejection for PEG having 1000 Da molecular weight. Contact angle and water swelling was measured to determine hydrophilicity of the membrane. Water swelling and salt rejection in different pH was also studied. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Nanofiltration membrane is a kind of membrane used in pressure driven filtration processes whose pore size lies between reverse osmo- sis and ultrafiltration membranes. In recent years, NF membranes are gaining more importance amongst the polymer chemists for the filtra- tion process owing to its advantages such as low operating pressure, high flux, and high retention of multivalent ions [1]. Nowadays NF membranes are commonly employed in water purification applications, such as ultra pure water production, water softening, desalination, waste water treatment [2–11]. One also finds its application in the separation of organics, heavy metal from water. Industrially they are important in pigment industries and pharmaceutical industries. NF separation is achieved by charge and size exclusion [12]. Charge on the membrane is positive below the iso-electric point and negative above it. The charge exclusion of ions is dependent on the charge of the membrane, the ionic strength and the valency of the ions. The latter two influence the membrane charge density and the iso-electric point. The size exclusion is dependent on the membrane structure, more dense structure leading to lower permeation. Presently, lot of research is going on for preparing efficient NF mem- branes. Bolong et al. in [13] 2010, reported that, charged membranes are more effective for removal of bisphenols from waste water. Abu Seman et al. [14] in 2011 developed membranes with antifouling properties and studied the performance of nanofiltration membranes modified by interfacial polymerization. Miao et al. [15] in 2006 prepared and char- acterized N,O-carboxymethyl chitosan (NOCC)/polysulfone (PSf) com- posite nanofiltration membranes. In that, ultrafiltration membrane of polysulfone was used to convert nanofiltration membrane by coating NOCC. Zhang et al. [16] in 2006 reported investigations on the structure and performance of a polypiperazine amide/polysulfone composite mem- brane. Polypiperazine was cross linked to the polysulfone membrane. Many literatures have reported polysulfone or modified polysulfone as the material for the NF membrane [17,18] due to its advantages such as high chemical resistance; tolerance to wide range of pH and ease of making composites with other polymers. Hydrophobic property of polysulfone affects on the productivity of the membrane [19]. In NF membranes, main challenge is to increase the flux and salt rejection while minimizing the operating pressure. According to Nowak (1989), transport and separation properties of Polysulfone membranes depend on the substrate composite with polysulfone [20]. Hydrophilic polymer is required to blend with polysulfone to increase the performance of the membrane. Keeping these challenges in view, we have designed NF blend membranes of different weight proportion of novel polymers and polysulfone by DIPS (Diffusion Induced Phase Separation) method. The main aim of this research is to increase the efficiency of the NF by using charged membranes. Poly(sulfonyl-amino-benzamide) and methylated poly(sulfonyl amino benzamide (PSAB and mPSAB) novel polymers were prepared. The novel polymer was characterized by FT-IR and NMR. Blend Desalination 295 (2012) 35–42 ⁎ Corresponding author. Tel.: + 91 824 2474000 3206; fax: + 91 824 2474033. E-mail address: isloor@yahoo.com (A.M. Isloor). 0011-9164/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2012.03.014 Contents lists available at SciVerse ScienceDirect Desalination journal homepage: www.elsevier.com/locate/desal