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Removal of organic contaminants by RO and NF membranesRejection characteristics of organic and inorganic compounds were examined for six reverse osmosis (RO) membranes and two nanofiltration (NF) membranes that are commercially available. A batch stirred-cell was employed to determine the membrane flux and the solute rejection for solutions at various concentrations and different pH conditions. The results show that for ionic solutes the degree of separation is influenced mainly by electrostatic exclusion, while for organic solutes the removal depends mainly upon the solute radius and molecular structure. In order to provide a better understanding of rejection mechanisms for the RO and NF membranes, the ratio of solute radius (r(i,s)) to effective membrane pore radius (r(p)) was employed to compare rejections. An empirical relation for the dependence of the rejection of organic compounds on the ratio r(i,s)/r(p) is presented. The rejection for organic compounds is over 75% when r(i,s)/r(p) is greater than 0.8. In addition, the rejection of organic compounds is examined using the extended Nernst-Planck equation coupled with a steric hindrance model. The transport of organic solutes is controlled mainly by diffusion for the compounds that have a high r(i,s)/r(p) ratio, while convection is dominant for compounds that have a small r(i,s)/r(p) ratio. c2005 Elsevier B.V. All rights reserved.
Document ID
20050218251
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Yoon, Yeomin
(Northwestern University Evanston, IL 60208-3111, United States)
Lueptow, Richard M.
Date Acquired
August 23, 2013
Publication Date
September 15, 2005
Publication Information
Publication: Journal of membrane science
Volume: 261
Issue: 1-2
ISSN: 0376-7388
Subject Category
Environment Pollution
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Life Sciences Technologies
Non-NASA Center

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