Performance and properties of modified poly (vinylidene fluoride) membranes using general purpose polystyrene (GPPS) by DIPS method Harsha P. Srivastava a , G. Arthanareeswaran a, ⁎, N. Anantharaman a , Victor M. Starov b a Membrane Research Laboratory, Department of Chemical Engineering, National Institute of Technology, Tiruchirappalli-620015, India b Department of Chemical Engineering, Loughborough University, Loughborough, LE11 3TU, UK abstract article info Article history: Received 30 November 2010 Received in revised form 15 February 2011 Accepted 18 February 2011 Available online 10 March 2011 Keywords: Poly(vinylidene fluoride) Polymer blend Thermal stability Treatment of distillery effluent An attempt has been undertaken to improve hydrophilic characteristics of poly(vinylidene fluoride) (PVDF) membrane by blending with amorphous polymer, polystyrene (GPPS) using conventional method of diffusion induced phase separation (DIPS). Blends of PVDF and GPPS have been prepared in 100:00, 95:05, 90:10, 85:15 and 00:100 ratio combinations. The morphology of blend membranes was investigated using scanning electron microscope (SEM), crystallite size and crystallinity was investigated using X-ray Diffractometer (XRD), pure water flux (PWF) and contact angle etc were also used. Pure water flux of 5% and 10% GPPS blend membranes went up to 14.0 and 16.5 Lm -2 h -1 as compared to10.9 Lm -2 h -1 for 100% PVDF membrane. Crystallinity and crystallite size of the PVDF–GPPS membranes reduced with increase in GPPS content in PVDF. However, according to our observation excess of 15% GPPS in blend membrane showed an incompatibility and heterogeneity in PVDF–GPPS membrane structure. The treatment of distillery effluent through 100% PVDF, 5% and 10% GPPS blend membranes was investigated and high molecular weight organics were separated. © 2011 Elsevier B.V. All rights reserved. 1. Introduction One of the most important challenges in long-term operation of membrane separation processes is the growth of foulant layer on membrane surfaces or fouling, which also may lead to the pore blocking. Fouling reduces the flux through the membrane, requires higher operating pressure, more frequent chemical cleaning, and results in a shorter membrane life. Design (modification) of membrane materials that resist fouling is therefore of utmost importance for sustainable use of membrane separation processes such as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO). Currently polymers are the most important available materials used for membrane formation. They provide a wide range of film forming and structure with desirable properties. Polymers can be modified to achieve tailored properties. Blending is a commonly used modification of polymers, which can provide desired properties such as solvent resistance, improved process character- istics, hydrophilicity, selectivity and high productivity [1]. Poly (vinylidene fluoride) (PVDF) is a polymer commercially available for membrane preparation, it has required mechanical, chemical and thermal properties. Being the member of vinyl family, PVDF provides the flexibility in membrane formation. However, PVDF has hydro- phobic character making its membranes prone for fouling. PVDF has low T g (glass transition temperature), in the range of -40 to -25 °C which effects its mechanical properties at above 75 °C. Membrane surface can be attached with hydrophilic functional group/compound by grafting [2] which increase hydrophilicity in PVDF. Researchers modified hydrophobicity of PVDF membrane by high energy radiation grafting [3], photo-radiation grafting [4], radio-chemical grafting [5] and plasma treatment [6,7]. PVDF is also copolymerized or blended successfully with polymers like poly methyl methacrylate (PMMA) [8], poly acrilonitrile (PAN) [9], with some active monomer like acrylic acid [10] and modified hydrophobicity of the resulting membranes. Polystyrene (PS) is homopolymer of styrene, member of vinyl with attached benzene ring and random presence of benzene ring create atactic character in polymer. General purpose polystyrene (GPPS) is atactic polystyrene which possess good mechanical, thermal and electrical properties but very poor ductility and impact property hence require the modification for potential applications. Polystyrene was successfully blended with various polymers [11–13] to enhance membrane properties. Physical blending of ultrafiltration (UF) mem- branes using hydrophilic monomers has been shown to be successful in increasing surface hydrophilicity and decreasing membrane fouling [9–11]. Kato et al. [11] prepared polystyrene–polycarbonate semi- miscible blend by casting from 1,4-dioxane solution. Deyrail et al. [12] reported the use of polystyrene as template in membrane preparation, from polyamide–polystyrene blend for gas diffusion. Cecile and Hsieh [13] utilized styrene copolymers for membrane preparation and achieved significant increase in hydrophilicity of membrane. Lehtinen Desalination 283 (2011) 169–177 ⁎ Corresponding author. Tel.: +91 431 2503118; fax: +91 431 2500133. E-mail addresses: arthanaree10@yahoo.com, arthanareeg@gmail.com (G. Arthanareeswaran). 0011-9164/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2011.02.042 Contents lists available at ScienceDirect Desalination journal homepage: www.elsevier.com/locate/desal