Effect of modified PVDF hollow fiber submerged ultrafiltration membrane for refinery wastewater treatment E. Yuliwati a,b , A.F. Ismail a,b, ⁎, T. Matsuura a,c , M.A. Kassim a , M.S. Abdullah a a Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, 81310 UTM, Skudai Johor, Malaysia b Faculty of Petroleum and Renewable Energy Engineering, Universiti Teknologi Malaysia, 81310 UTM, Skudai Johor, Malaysia c Department of Chemical Engineering, Industrial Membrane Research Laboratory, University of Ottawa, Ont., Canada KIN 6N5 abstract article info Article history: Received 1 January 2011 Received in revised form 16 March 2011 Accepted 17 March 2011 Available online 27 April 2011 Keywords: PVDF membrane Ultrafiltration Surface hydrophilicity Hollow fiber Submerged ultrafiltration process was studied for treatment of refinery wastewater using PVDF hollow fiber membranes. The membranes were prepared via the phase inversion method by dispersing LiCl·H 2 O and TiO 2 in the dope to study the effects of surface properties on membrane performance. The comparison of the performance and morphology was conducted on prepared PVDF composite membranes with various LiCl·H 2 O and TiO 2 contents. The hollow fiber membranes were characterized by field emission scanning electron microscope (FESEM) and energy dispersive x-ray (EDX), average pore size and effective porosity measurements, contact angle measurement, permeability and rejection test. Maximum results were observed for membrane hydrophilicity, membrane porosity and average pore size when the TiO 2 concentration was 1.95%. It was also found that interactions between the membrane surface and suspended solid constituents strongly influenced the membrane fouling. The maximum flux and rejection of refinery wastewater were 82.5 L/m 2 h and 98.8%, respectively, when the PVDF composite membrane with TiO 2 content of 1.95% is used at pH = 6.9. © 2011 Elsevier B.V. All rights reserved. 1. Introduction A stringent environmental regulations and legislation have driven a great effort to seek alternative technologies for wastewater separation, which have the following important features: enhanced efficiency, self- sustainability, and absence of hazardous wastes. Several common techniques have been improved for removing soluble and insoluble of organic and inorganic contaminants from refinery wastewater, such as gravity settling separation and mechanical coalescence, coagulation and air flotation, electrostatic and electrocoagulation separation. However, these methods would lead to a huge production of sludge and complicated operation problems. Membrane technologies have enjoyed great popularity over the last 30 years and been extensively used in separation facilities to separate liquid/liquid or liquid/solid mixtures due to the flexibility and ability to remove the contaminant from wastewater to very low levels [1,2]. Moreover, because of its suitable pore sizes (usually in the range of 2–50 nm) and capability of removing emulsified oil droplets and other organic contaminant, ultrafiltration has been demonstrated as an efficient method in refinery wastewater treatment [3–5]. The ultrafiltration membrane is mainly classified into two kinds, namely, polymeric membranes and inorganic membranes. Due to the distinct advantages such as temperature and wear resistance, well- defined stable pore structure, and chemical inertness, the inorganic membranes such as, ceramic and carbon membranes are quite suitable for processes involving high temperatures and harsh chemical environ- ments and have been successfully applied to the refinery wastewater treatment [6–8]. However, inorganic membranes display some inherent disadvantages and majority of them are related to their relatively high cost arising from the expensive materials, the complicated fabrication procedure and the low membrane surface [9]. Hence, the cheap and easy-fabricating polymeric membranes are still dominating the mem- brane market. It should be pointed out that the serious membrane fouling caused by nonspecific adsorption and/or deposition of the foulant onto the membrane surfaces, often results in a substantial decline of the permeate flux with operation time and consequently limits their wide application in the wastewater treatment [10]. Many investigations have demonstrated that modifying membrane surface, such as hydrophilicity, pore size, porosity and, surface charge effectively inhibited the nonspecific adsorption and consequently decreases membrane fouling and significantly increases the permeate flux [11–14]. Polyvinylidene fluoride (PVDF) is regarded as one of the most attractive polymer materials in microporous membrane industry. The molecular structure of PVDF homopolymer with alternating CH 2 and CF 2 groups along the polymer chain forms a unique polymer. It provides extraordinary mechanical properties, high chemical resistance, good thermal stability and excellent membrane forming abilities [15]. Therefore, PVDF is a suitable material to make membranes, which Desalination 283 (2011) 214–220 ⁎ Corresponding author at: Advanced Membrane Technology Research Center (AMTEC), Universiti Teknologi Malaysia, 81310 UTM, Skudai Johor, Malaysia. Tel.: +60 7 553 5592; fax: +60 7 558 1463. E-mail address: afauzi@utm.my (A.F. Ismail). 0011-9164/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2011.03.049 Contents lists available at ScienceDirect Desalination journal homepage: www.elsevier.com/locate/desal