Fouling-resistant ceramic-supported polymer membranes for ultrafiltration of oil-in-water microemulsions

Fouling-resistant ultrafiltration ceramic-supported polymer (CSP) ultrafiltration membrane was developed for the treatment of oil-in-water (o/w) microemulsions. The CSP zirconia-based membrane was prepared via free-radical graft polymerization of vinylpyrrolidone onto the membrane surface. Pore reduction of about 25–28% was encountered upon modification as revealed by hydraulic permeability measurements. Oil rejection was higher for grafted membranes with smaller resultant pore size. Atomic force microscopy imaging of polymer-modified surfaces showed complete surface coverage by the polymer chains. The native zirconia membrane was irreversibly fouled after treating the o/w microemulsion for a brief period, while the CSP membranes maintained its pre-filtration hydraulic permeability even after many filtration runs. The present surface modification was found to be effective in preventing irreversible membrane fouling despite significant membrane surface roughness. Relative to the native membrane, oil rejection of the CSP membrane increased more than two-fold for the range of studied oil droplet size (18–66 nm), while surfactant rejection remained low for both the native and modified membranes.