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Generation and Control of Electrohydrodynamic Flows in Aqueous Electrolyte Solutions
Published on: September 7, 2018
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Electroviscous Effects in Ceramic Nanofiltration Membranes.
Ali Farsi1, Vittorio Boffa1, Morten Lykkegaard Christensen2
1Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, 9220, Aalborg East, Denmark.
Summary
This study models γ-alumina nanofiltration membrane performance, predicting salt rejection and solvent flux using advanced equations. Findings reveal how ion adsorption impacts membrane permeability and suggests optimizing membranes for specific conditions.
Area of Science:
- Materials Science
- Chemical Engineering
- Physical Chemistry
Background:
- Nanofiltration membranes are crucial for water purification and separation processes.
- Understanding membrane surface charge and pore characteristics is key to predicting performance.
- γ-alumina membranes offer potential for various separation applications.
Purpose of the Study:
- To model and predict the salt rejection and solvent flux of γ-alumina nanofiltration membranes.
- To investigate the influence of ion adsorption and surface charge (ζ-potential) on membrane performance.
- To develop a predictive tool for optimizing membrane perm-selectivity.
Main Methods:
- Utilized the Donnan-steric pore model and extended Nernst-Planck equation for ion transport.
- Applied the Hagen-Poiseuille equation with electroviscosity for solvent flux modeling.
- Conducted ζ-potential measurements on γ-alumina particles to assess ion adsorption.
Main Results:
- Monovalent ions showed minimal adsorption, while divalent ions adsorbed significantly onto the γ-alumina surface.
- Ion adsorption led to pore shrinkage, particularly affecting membrane permeability for smaller pore sizes (<3 nm).
- An optimal ζ-potential was identified for maximizing salt rejection under specific low ionic strength conditions (<0.01 m).
Conclusions:
- The developed model accurately predicts nanofiltration membrane performance based on pore size and surface charge.
- Membrane permeability is significantly influenced by ζ-potential, especially for small pores and low ionic strengths.
- The model serves as a valuable tool for designing tailored γ-alumina membranes for specific separation tasks and conditions.
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