Hierarchically porous silica particles: One-pot synthesis, tunable hydrophilic/hydrophobic properties, prospects for selective oil adsorption

Submicron spherical silica particles were synthesized via base hydrolysis of tetraethoxysilane (TEOS) and phenyltriethoxysilane (PTEOS) in a presence of cetyltrimethylammonium bromide. It was shown that the replacement of a part of TEOS with PTEOS in the reaction mixture led to formation of particles containing hierarchical micro-mesoporous structure with specific surface area of up to similar to 1170 m(2) g(-1). The amount of PTEOS leads to the increase of water contact angle of the particles from 10 degrees to 155 degrees which causes a gradual change in their surface properties from hydrophilic to superhydrophobic. The static adsorption capacity of the particles was measured for water, toluene and methyl isobutyl ketone and was found to be affected by both the amount of OH- or C6H5-groups on the surface and the characteristics of porosity. In particular, the adsorption capacity for non-polar volatile organics increases with the increase of the hydrophobicity of particles. It was found that synthesized superhydrophobic silica particles efficiently and quickly absorb oil from water surface and then can be easily removed mechanically.