Carbon nanotube blended polyethersulfone membranes for fouling control in water treatment Evrim Celik, Hosik Park, Hyeongyu Choi, Heechul Choi* Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, South Korea article info Article history: Received 3 May 2010 Received in revised form 13 July 2010 Accepted 19 July 2010 Available online 27 July 2010 Keywords: Ultrafiltration Fouling control Multi-walled carbon nanotubes Polyethersulfone Composite membrane Hydrophilicity abstract Multi-walled carbon nanotube/polyethersulfone (C/P) blend membranes were synthesized via the phase inversion method. The resultant membranes were then characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and contact angle. The C/P blend membranes appeared to be more hydrophilic, with a higher pure water flux than the polyethersulfone (PES) membranes. It was also found that the amount of multi-walled carbon nanotubes (MWCNTs) in the blend membranes was an important factor affecting the morphology and permeation properties of the membranes. After 24 h of surface water filtration with 7 mgC/L TOC content, the C/P blend membranes displayed a higher flux and slower fouling rate than the PES membranes. Subsequent analyses of the desorbed foulants showed that the amount of foulant on bare PES membranes was 63% higher than the C/P blend membrane for 2% MWCNTs content. Thus, the carbon nanotube content of the C/P membranes was shown to alleviate the membrane fouling caused by natural water. ª 2010 Published by Elsevier Ltd. 1. Introduction Membrane technology has been commonly used worldwide for the removal of suspended solids such as microorganisms and a fraction of dissolved solids (Choi et al., 2005). Based on this technology, separation, concentration, and purification have become industrially viable because of the high separa- tion efficiency of these membranes. Moreover, their low energy requirement, low space requirement, and simplicity of operation promote their use in separation processes (Arthanareeswaran et al., 2004). However, fouling is still a major problem limiting the wider application of membrane operations (Cheryan, 1986), which can be defined as the reversible or irreversible deposition of retained solutes such as particles, colloids, emulsions, macromolecules, salts, etc. on or in the membrane (Mulder, 1997). Membrane surface chemistry is a very important factor determining the performance of ultrafiltration operations (Reddy and Patel, 2008). The nature of these membranes easily induces macromolecules to deposit because of their hydro- phobic regions (Blanco et al., 2006). To this end, it is well known that increasing the membrane hydrophilicity can effectively minimize membrane fouling (Wang et al., 2006), though charged membranes can also be used to reduce membrane fouling (Mulder, 1997). As such, methods such as surface graft polymerization, chemical grafting, and radiation induced grafting have been developed in attempts to increase the surface hydrophilicity of membranes (Shi et al., 2007; Wang et al., 2006). In addition, there has been a great deal of interest in the use of organiceinorganic hybrid membranes as a potential next generation membrane material. It is expected that such * Corresponding author. Tel.: þ82 62 715 2441; fax: þ82 62 715 2434. E-mail address: hcchoi@gist.ac.kr (H. Choi). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/watres water research 45 (2011) 274 e282 0043-1354/$ e see front matter ª 2010 Published by Elsevier Ltd. doi:10.1016/j.watres.2010.07.060