Fluorine-free and hydrophobic hexadecyltrimethoxysilane-TiO2 coated mesh for gravity-driven oil/water separation

Superhydrophobic and superoleophilic meshes have attracted great attention in oil/water separating application. However, superhydrophobic surfaces are not only complicated in preparation but also easy to break in practical applications. In this paper, we prepared fluorine-free hydrophobic hexadecyltrimethoxysilane (HDTMS)-TiO2 coated meshes with properties of cost-effectiveness, easy to manufacture, and high separation efficiency by a liquid phase deposition method. The surface topography, composition, and functional groups of the meshes were characterized by field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Fourier transform microscopic infrared spectrometer (FT-IR) spectrum, respectively. A new gravity-driven oil/water separator was designed for the separation experiments. The separation efficiency of the hydrophobic HDTMS-TiO2 coated meshes maintained over 97.8% after 35 separating cycles. This study indicated that the superhydrophobicity of the separating mesh was nonessential for the highly efficient oil-water separation. The fluorine-free hydrophobic HDTMS-TiO2 coated meshes provided an economical and beneficial solution to treat industrial oily wastewater mixtures and environmental oil spills.