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Updated: Jun 12, 2026
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Merging Ion Concentration Polarization between Juxtaposed Ion Exchange Membranes to Block the Propagation of the Polarization Zone
Published on: February 23, 2017
Experimental studies and modeling on concentration polarization in forward osmosis
Jian-Jun Qin1, Sijie Chen, Maung Htun Oo
1Technology and Water Quality Office, Public Utilities Board, 82 Toh Guan Road East, #C4-03, 608575 Singapore, Republic of Singapore. QIN_Jianjun@pub.gov.sg
Summary
Concentration polarization significantly limits forward osmosis flux, primarily due to internal effects. Optimizing draw solutions and membrane properties can enhance water flux in FO processes.
Area of Science:
- Chemical Engineering
- Water Treatment Technologies
- Membrane Science
Background:
- Concentration polarization (CP) is a critical challenge in forward osmosis (FO), impacting process efficiency.
- The combined effects of dilutive internal CP (DICP) and concentrative external CP (CECP) are thought to limit FO flux.
Purpose of the Study:
- To differentiate the individual contributions of DICP and CECP to FO flux limitations using modeling.
- To validate modeling predictions through pilot-scale studies.
Main Methods:
- Developed and applied a concentration polarization model derived from previous research.
- Conducted bench-scale FO experiments using drinking water as feed and varying NaCl/MgSO(4) draw solutions.
- Investigated the influence of draw solution concentration and velocity on FO flux.
Main Results:
- Modeling indicated DICP caused a 99.9% flux reduction with 0.5 M NaCl draw solution, even under turbulent flow.
- Draw solution selection was identified as a key factor for improving DICP.
- Modeling results showed strong agreement with experimental data.
Conclusions:
- The developed model accurately predicts water flux and aids in draw solution selection for FO.
- Higher water flux is achievable with draw solutions possessing greater diffusion coefficients or thinner FO membrane substrates.
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