Effect of Hypochlorite Treatment on Performance of Hollow Fiber Membrane Prepared from Polyethersulfone/N-Methyl-2-Pyrrolidone/Tetronic 1307 Solution Nasrul Arahman, 1,2 Tatsuo Maruyama, 1 Tomohiro Sotani, 1 Hideto Matsuyama 1 1 Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkodai, Nada-Ku, Kobe 657-8501, Japan 2 Department of Chemical Engineering, Syiah Kuala University, Banda Aceh 23111, Indonesia Received 16 February 2008; accepted 15 May 2008 DOI 10.1002/app.28719 Published online 9 July 2008 in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: Polyethersulfone (PES) hollow fiber mem- brane was prepared by blending with nonionic surfactant Tetronic 1307 to improve its hydrophilicity. The mem- branes were posttreated by hypochlorite solution of 10, 100, 500, and 2000 ppm. The effect of hypochlorite treat- ment on the performance of PES membrane was investi- gated. Experimental results showed that the water permeability of treated membrane was two to three times higher than that of untreated membrane in case of blend membrane prepared from PES/N-methyl-2-pyrrolidone (NMP)/Tetronic 1307 solution. On the other hand, hypo- chlorite treatment has no effect on water permeability of the membrane prepared from PES/NMP solution. Ele- mental analysis and ATR–FTIR measurement results indi- cated that hypochlorite treatment led to decomposition and leaching out of Tetronic 1307 component from the membrane. The change of membrane surface structure by the hypochlorite treatment was confirmed by atomic force microscopy measurement. The hypochlorite treatment brought about no significant impact on the mechanical property of the membranes. This indicated that the hypo- chlorite treatment of PES membrane prepared with sur- factant was a useful way to improve the water permeability without the decrease of membrane strength. V V C 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 687–694, 2008 Key words: polyethersulfone; hollow fiber membrane; nonsolvent-induced phase separation; hypochlorite treat- ment; tetronic 1307 INTRODUCTION Microfiltration and ultrafiltration have been becom- ing an interesting methods for producing safety drinking water. These membrane processes have been attracting much attention throughout the world due to their highly efficient removal properties of particulates, virus, and bacteria. To be useful in industrial water treatment, membranes with high flux, high rejection, high mechanical stability, and good chemical resistance must be developed. 1 Poly- ethersulfone (PES) polymer is one of the polymers most frequently used in the preparation of micro- filtrtion and ultrafiltration membranes due to its excellent chemical resistance, good thermal stability, and mechanical properties. Many researchers have focused their efforts to minimize hydrophobic prop- erty of PES, which is the main drawback of this polymer. To improve the hydrophilicity, PES mem- brane was blended with the hydrophilic polymer additives, such as polyvinylpyrrolidone (PVP), cellu- lose acetate phthalate (CAP), and Pluronic F127 (polymeric surfactant). 2–4 On the other hand, the addition of large amount of hydrophilic polymer additive on the membrane preparation solution resulted in decrease of water permeability. 5 Hypochlorite posttreatment of PES membrane-con- taining polymeric additive has been introduced as a method to enhance water permeability. Qin et al. 2 reported in their investigation that water permeabil- ity of PES membrane blended with PVP was increased five times after soaked in hypochlorite so- lution of 4000 ppm for 48 h. Wienk et al. 6 also found the water permeability increase in PES/PVP blend membrane by increasing the immersing time in hy- pochlorite solution. They suggested that hypochlo- rite posttreatment may increase pore size of membrane by a reaction of hypochlorite with PVP. In our previous work, new surfactant Tetronic 1307 was added to the membrane preparation solu- tion as a membrane-modifying agent to improve the hydrophilicity of PES membrane. 7 Tetronic, which is commercially also available as Poloxamines, is a family of surfactants with X-shaped copolymers. It is Journal of Applied Polymer Science, Vol. 110, 687–694 (2008) V V C 2008 Wiley Periodicals, Inc. Correspondence to: H. Matsuyama (matuyama@kobe-u.ac.jp).