Fluorine-functionalized mesoporous alumina materials with superhydrophobic surfaces

Mesoporous alumina has been widely used in catalysis, adsorption, and drug delivery, in which the specific application of mesoporous alumina depends on the functionalization of its surface. However, mesoporous alumina has been rarely studied in the functionalization of superhydrophobic surfaces, which limits the wide application of mesoporous alumina. To address this limitation, we developed a fluorinated alumina material with a superhydrophobic surface by grafting 1H,1H,2H,2H-perfluorodecyltriethoxysilane onto the surface of mesoporous alumina. The water contact angle of fluorinated alumina reached as high as 163.00°. As compared with mesoporous alumina, the specific surface area of fluorinated alumina was much smaller, dropping from 136 m2/g to 44 m2/g. Meanwhile, fluorinated alumina had a large surface roughness (Rq = 35.7 nm). Interestingly, with the increase of the amount of fluorinated silane in the grafting reaction, the water contact angle of fluorinated alumina initially increased and then decreased. The high flux (6.084*106 L/m2·h·pa) and great separation efficiency (>99%) were obtained with great repeatability in the in oil-water separation. Even this fluorinated alumina can efficiently separate the water-in-oil emulsions. Therefore, this work opens a new platform for the application of superhydrophobic mesoporous alumina in oil-water separation.