Hydrophilic modification of Al2O3 microfiltration membrane with nano-sized γ-Al2O3 coating

To reduce the membrane fouling of oil-water emulsion, the commercial Al2O3 microfiltration membrane (MF) was modified with nano-sized Al2O3 grains by in-situ hydrolysis method. The nano coating formed by the Al2O3 grains and the modified MF were characterized. The results show that the nano-sized Al2O3 grains were only deposited on the surfaces of the Al2O3 grain in the MF. The coating does not act as a filter layer, just changes the character of the membrane surface which becomes more hydrophilic. The coating decreases the mean pore sizes of the modified MF by 12.5%, but increases the pure water flux by about 27% due to the existence of the boundary slip. The hydrophilic coating prevents the modified MF from being fouled using stable emulsion as feed. The water flux of the modified MF increases 20% than the unmodified one. The effects of cross-flow velocity on the flux and the oil rejection are also discussed.