Oil-mists coalescence performance of fibrous filters with superoleophilic and superoleophobic surface.

• Effect of superoleophilic and superoleophobic treatment on coalescence performance was investigated experimentally. • The superoleophilic filter shows a significant reduction on wet pressure drop at saturation stage. • Effect of the fiber surface energy on the morphology of liquid bridge was discussed. • Coalescence performance of combination filter containing superoleophilicity and superoleophobicity was studied. • The drainage layer strategy has no advantage for improving coalescence performance. The surface wettability of fibers in coalescing filter has a critical effect on filter's performance. In this study, we employed common glass fiber filters as model and prepared superoleophilic and superoleophobic surface filters via a facile dip-coating method. The superoleophilic treatment shows a considerable reduction in pressure drop. The wet pressure drop at saturation decrease from 12.91 kPa to 8.56 kPa after superoleophilic coating. The filtration efficiency of fine particles (<100 nm) increase owing to coating treatment. The combinations of superoleophilic and superoleophobic filter and drainage strategy were also evaluated. The results show that the combination has no advantage due to emergency turn of wettability. The drainage layer with appropriate rank could enhance the drainage rate at unsaturation stage. However, the drainage strategy is never a good idea to improving coalescence performance because it brings the extra pressure drop. [ABSTRACT FROM AUTHOR]