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Volume 1, Number 2, April 2010

This study examined the effects of feed water chemistry and membrane fouling on the rejection of trace organics by a loose nanofiltration membrane. One ionisable and one non-ionisable trace organics were selected for investigation. Results reported here indicate that the solution pH and ionic strength can markedly influence the removal of the ionisable trace organic compound sulfamethoxazole. These observations were explained by electrostatic interactions between the solutes and the membrane surface and by the speciation of the ionisable compound. On the other hand, no appreciable effects of solution pH and ionic strength on the rejection of the neutral compound carbamazepine were observed in this study. In addition, membrane fouling has also been shown to exert some considerable impact on the rejection of trace organics. However, the underlying mechanisms remain somewhat unclear and are subject to on-going investigation.

Key Words
nanofiltration; trace organics; operating conditions; water recycling; membrane fouling.

Long D. Nghiem; School of Civil, Mining & Environmental Engineering The University of Wollongong, Australia NSW 2522

Surface modification of microfiltration and ultrafiltration membranes has been widely used to improve the protein adsorption resistance and permeation properties of hydrophobic membranes. Several surface modification methods for converting conventional membranes into low-protein-binding membranes are reviewed. They are categorized as either physical modification or chemical modification of the membrane surface. Physical modification of the membrane surface can be achieved by coating it with hydrophilic polymers, hydrophilic-hydrophobic copolymers, surfactants or proteins. Another method of physical modification is plasma treatment with gases. A hydrophilic membrane surface can be also generated during phase-inverted micro-separation during membrane formation, by blending hydrophilic or hydrophilichydrophobic polymers with a hydrophobic base membrane polymer. The most widely used method of chemical modification is surface grafting of a hydrophilic polymer by UV polymerization because it is the easiest method; the membranes are dipped into monomers with and without photo-initiators, then irradiated with UV. Plasma-induced polymerization of hydrophilic monomers on the surface is another popular method, and surface chemical reactions have also been developed by several researchers. Several important examples of physical and chemical modifications of membrane surfaces for low-protein-binding are summarized in this article.

Key Words
surface modification; ultrafiltration; microfiltration; fouling; biofouling; low-protein-binding.

Akon Higuchi; Department of Chemical and Materials Engineering, National Central University, No. 300, Jhongda Rd., Jhongli, Taoyuan, 32001 Taiwan
Department of Reproduction, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo 157-8535, Japan
Cathay Medical Research Institute, Cathay General Hospital, No. 32, Ln 160, Jian-Cheng Road, Hsi-Chi City, Taipei, 221, Taiwan
Miho Tamai and Yoh-ichi Tagawa; Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology,
B-51 4259 Nagatsuta-cho, Midori-ku, Yokohama , Kanagawa 226-8501, Japan
Yung Chang; Department of Chemical Engineering, R&D Center for Membrane Technology, Chung Yuan Christian University, 200, Chung-Bei Rd., Chungli, Taoyuan 320, Taiwan
Qing-Dong Ling; Cathay Medical Research Institute, Cathay General Hospital, No. 32, Ln 160, Jian-Cheng Road, Hsi-Chi City, Taipei, 221, Taiwan
Institute of Systems Biology and Bioinformatics, National Central University, No. 300, Jhongda RD., Jhongli, Taoyuan, 32001 Taiwan

This work presents inexpensive inorganic precursor formulations to yield submicron range symmetric ceramic microfiltration (MF) membranes whose average pore sizes were between 0.1 and 0.4

Key Words
ceramic membrane; submicron; kaolin; oil-in-water; sintering.

B.K. Nandi, B. Das, R. Uppaluri and M.K. Purkait; Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati - 781039, Assam, India

This work focuses on the application of nanofiltration (NF) to the concentration of a pharmaceutical product, Clavulanate (CA−), from clarified fermentation broths, which show a complex composition with six main identified ions (K+, Cl−, NH4 +, H2PO4 −, SO4 2− and CA−), glucose and glycerol. The solutes transport through the NF membrane pores was investigated using the SEDE (Steric, Electric and Dielectric Exclusion) model. This model was applied to predict the rejection rates of the initial feed solution and the final concentrated solution (10-fold concentrated solution). The best results were achieved with a single fitted parameter,

Key Words
nanofiltration; multi-ionic solutions; transport model; membrane charge; concentration polarization.

A.I. Cavaco Morao; 1nstituto Superior Tecnico, Department of Chemical and Biological Engineering, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
A. Szymczyk; Universite Europeenne de Bretagne, France
Universite de Rennes 1, CNRS, Laboratoire des Sciences Chimiques de Rennes, UMR 6226 CNRS/UR1/ENSCR, Chimie et Ingenierie des Procedes, 263 Av. du General Leclerc,
Bat. 10 A, CS 74205, F-35042 Rennes, France
P. Fievet; Institut UTINAM, UMR CNRS 6213, Universite de Franche-Comte, 16 route de Gray,Besancon Cedex 25030, France
A.M. Brites Alves; 1nstituto Superior Tecnico, Department of Chemical and Biological Engineering, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal

The effect of external recycle on the performance of dialysis in countercurrent-flow rectangular membrane modules was investigated both theoretically and experimentally. Theoretical analysis of mass transfer in parallel-flow device with and without recycle is analogous to heat transfer in parallel-flow heat exchangers. Experiments were carried out with the use of a microporous membrane to dialyze urea aqueous solution by pure water. In contrast to a device with recycle, improvement in mass transfer is achievable if parallel-flow dialysis is operated in a device of same size with recycle which provides the increase of fluid velocity, resulting in reduction of mass-transfer resistance, especially for rather low feed volume rate.

Key Words
dialysis; external recycle; parallel flow.

Ho-Ming Yeh, Tung-Wen Cheng and Kuan-Hung Chen; Department of Chemical and Materials Engineering, Tamkang University, Tamsui, Taipei 25137, Taiwan

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