Desalination 14x (2002) 000–000 Presented at the International Congress on Membranes and Membrane Processes (ICOM), Toulouse, France, July 7–12, 2002. 0011-9164/02/$– See front matter © 2002 Elsevier Science B.V. All rights reserved PROOF ICOM 502 *Corresponding author. The relationship between flux decline of NF membranes with NOM transport characteristics: convection vs. diffusion Sangyoup Lee a , Jihee Moon a , Seong-Keun Yim b , Seung-Hyeon Moon a , Jaeweon Cho a* a Department of Environmental Science and Engineering, Kwangju Institute of Science and Technology (K-JIST), Oryong-dong, Buk-gu 500-712, Gwangju, Korea Tel. +82 (62) 970-2443; Fax +82 (62) 970-2434; email: choj@kjist.ac.kr b R&D Center, Kolon Engineering & Construction, Yongin, Korea Received 20 February 2002; accepted 6 March 2002 Abstract Recent studies have shown that NF membranes can effectively remove natural organic matter (NOM). However, NOM also serves as an organic foulant to membranes, resulting in flux decline. In this study, the flux decline of NF membranes was analyzed through the transport characterization of NOM in NF membrane pores. The transport of NOM through NF membrane pores was influenced by either convection or diffusion, depending on the applied hydrodynamic operating conditions, as represented by the ratio J 0 /k (J 0 represents the initial pure water flux, and k is the mass transfer coefficient) [1]. Different behaviors of flux decline, and flux recovery of tested membranes could be obtained: depending on which transport mechanism (either convection or diffusion) dominates during NOM filtrations. The removal (or rejection) behavior of NOMs, by NF membranes, was evaluated with respect to the ratio J 0 /k under a dominant transport condition, along with the performance of the flux decline effects. Keywords: Natural organic matter (NOM); NF membrane; Diffusion and convection transport 1. Methods and materials The properties of the tested membranes are shown in Fig. 1 In terms of zeta potential against varying pH, and form the ATR-FTIR spectra, it can be seen that, the HL membrane exhibits higher negative surface charge compared to the ESNA membrane, with greater intensities, with respect to ionizable carboxylic functional groups (–COOH) (1210–1320 cm –1 ), as shown from the IR spectrum. The HL membrane also exhibits higher pure water permeability than the ESNA membrane (2.99 vs. 1.88 L/d-m 2 -kPa) even with similar molecular