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Oil-Water Separations

brushoilwaterOil-contaminated water is an unavoidable result of oil production and other industrial processes. Many membranes can readily pass water while rejecting even the smallest oil droplets, but membrane fouling with adsorbed oil leads to low productivity or high energy costs in these separations. This work is investigating the fouling resistance of new hydrophilic membrane coatings as well as the mechanism by which these coatings reject oil and resist fouling.

Polyelectrolyte brushes swell in water to provide a surface that does not wet with oil. Graduate student Zhefei Yang is investigating how this resistance to oil adsorption varies with the charge of the surfactant that stabilizes the oil-in-water emulsion. He found that the polymer brush must have a charge opposite to that of the surfactant to resist oil fouling. In the presence of an oppositely charged surfactant, adsorption of the surfactant may cause the brush to become less hydrophilic and collapse (see Langmuir20153111790–11799).  Current work is exploring how zwitterionic polymer brushes resist oil adsorption.  

Zhefei Yang
Graduate student Zhefei Yang develops hydrophilic polymer brushes to resist oil fouling.
An EPA STAR program (Grant R835183) funded work developing hydrophilic coatings for crossflow filtration, and this project is a collaboration with Professor Volodymyr Tarabara's group in Environmental Engineering at MSU. An NSF PIRE grant (OIS 1243433) funds research on visualization of oil droplet coalescence and development of methods to visualize oil droplets at the membrane surface. This is also a collaborative effort with Professor Tarabara's group.