Synthesis and characterization of superhydrophobic fluorinated mesoporous silica for oil/water separation

The classical mesoporous silica (MS) has been widely applied in various fields, including catalysis, adsorption, biology, drug delivery, and so on. In fact, the specific applications of MS were dependent on its surface functionality. However, the hydrophobic MS has not been well established to date. In this work, the hydrophobic MS was developed through the surface grafting of the perfluoroalkyl group using the fluorinated organosilane (1H,1H,2H,2H-perfluorodecyltriethoxysilane). Specifically, the corresponding structure, surface areas, pore-volume, and thermal properties of hydrophobic MS samples were characterized. After the surface grafting, the structure of fluorinated MS remained unchanged. However, the specific surface area decreased from 808 m 2 /g to 390 m 2 /g, and its pore size reduced from 6.2 nm to 4.3 nm. With the increase of fluorosilane content, the MS samples were gradually converted from an initial hydrophilic surface to a superhydrophobic surface with a contact angle up to 156.50°. Moreover, a typical “hills and valleys” surface type for the fluorinated MS was observed due to the obvious surface particle attachment. In the oil-water mixture and the water-in-oil emulsion separation, the separation efficiency was greatly high (>99%) with great stability. Therefore, the fluorinated MS would be expected to provide a potential solution for oil-water remediations. • A superhydrophobic mesoporous silica was developed by surface grafting. • After surface grafting, both surface area and pore size were decreased. • Superhydrophobic fluorinated MS has a contact angle of 156.50. • The oil-water mixture separation efficiency with fluorinated MS was >99%.