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Membrane Water Treatment   Volume 6, Number 2, March 2015, pages 127-139
DOI: https://doi.org/10.12989/mwt.2015.6.2.127
 
Inverse HPLC approach for the evaluation of repulsive interaction between ionic solutes and a membrane polymer
Yoshiaki Kiso, Yuki Kamimoto, Katsuya Hosogi and Yong-Jun Jung

 
Abstract     [Buy Article]
    Rejection of ionic solutes by reverse osmosis (RO) and nanofiltration (NF) membranes is controlled mainly by electrochemical interaction as well as pore size, but it is very difficult to directly evaluate such electrochemical interaction. In this work, we used an inverse HPLC method to investigate the interaction between ionic solutes and poly (m- phenylenediaminetrimesoyl) (PPT), a polymer similar to the skin layer of polyamide RO and NF membranes. Silica gel particles coated with PPT were used as the stationary phase, and aqueous solutions of the ionic solutes were used as the mobile phase. Chromatographs obtained for the ionic solutes showed features typical of exclusion chromatographs: the ionic solutes were eluted faster than water (mobile phase), and the exclusion intensity of the ionic solute decreased with increasing solute concentration, asymptotically approaching a minimum value. The charge density of PPT was estimated to be ca. 0.007 mol/L. On the basis of minimum exclusion intensity, the exclusion distances between a salt and neutralized PPT was examined, and the following average values were obtained: 0.49 nm for 1:1 salts, 0.57 nm for 2:1 salts, 0.60 nm for 1:2 salts, and 0.66 nm for 2:2 salts. However, NaAsO2 and H3BO3, which are dissolved at neutral pH in their undissociated forms, were not excluded.
 
Key Words
    reverse osmosis; nanofiltration; polyamide; ionic solute; electrochemical interaction; HPLC
 
Address
(1) Yoshiaki Kiso, Katsuya Hosogi:
Department of Environmental and Life Sciences, Toyohashi University of Technology, Tempaku-cho, Toyohashi 441-8586, Japan;
(2) Yuki Kamimoto:
EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan;
(3) Yong-Jun Jung:
Department of Environmental engineering, Catholic University of Pusan, Oryundae-ro, Geumjeong-gu, Busan, 609-757, Korea.
 

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