Facile Preparation of Fluoroalkyl End-Capped Vinyltrimethoxysilane Oligomer/Sand Composites Possessing Superoleophilic/Superhydrophobic Characteristic: Application to Oil/Water Separation and Selective Removal of Fluorinated Aromatic Compounds from Aqueous Methanol Solution

Abstract

Fluoroalkyl end-capped vinyltrimethoxysilane oligomer [R F -(CH 2 -CHSi(OMe) 3 ) n -R F : n = 2, 3, R F = CF(CF 3 )OC 3 F 7 : R F -(VM) n -R F ], was applied to the facile preparation of the corresponding oligomer/sand (Ottawa sand: OS) composites [R F -(VM-SiO 3/2 ) n -R F /OS] through the sol-gel reaction of the oligomer in the presence of micro-sized OS particles (590 - 840 μm) under alkaline conditions at room temperature. FE-SEM (Field Emission Scanning Electron Micrograph) images showed that the obtained composites con-sist of the R F -(VM-SiO 3/2 ) n -R F oligomeric nanoparticles and the micro-sized OS particles. Interestingly, the R F -(VM-SiO 3/2 ) n -R F /OS composites thus obtained can provide the superoleophilic/superhydrophobic characteristic on the composite surface, applying to the separation of not only the nated micro-sized controlled silica gel (μ-SiO 2 ) composites (average particle size: 9.5 μm), which were prepared under similar conditions. In addition to the separation of oil/water, the fluorinated OS composites provided higher and more selective removal ability for the fluorinated aromatic compounds from aqueous solutions than that of the μ-SiO 2 composites.