Study on pervaporation performance of hydrophobically modified carbon-based membrane materials

Abstract

Abstract Based on the appropriate pore size, the surface of the carbon membrane was hydrophobically modified to preferentially adsorb alcohols, so as to achieve the purpose of enriching alcohols in the penetrant. This operation is significant for expanding the application of carbon membranes for gas separation. In this work, a hydrophobic silica sol was synthesized using tetraethyl orthosilicate (TEOS) and methyltriethoxysilane (MTES) as mixed silicon sources, and it was impregnated and coated on a rolled carbon membrane. The material was then dried and thermally treated to obtain the hydrophobic carbon membrane. The preparation procedure of silica sol was also investigated, and the surface chemical structure and morphology of the hydrophobic carbon membrane were characterized by contact angle (CA), Fourier Transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM). The pervaporation performance of the hydrophobic carbon membrane was inspected with both ethanol/water and isopropanol/water mixed solution. The results showed that the hydrophobic carbon membrane has favorable pervaporation performance. With the elevation of temperature, the total flux significantly increased while the selectivity slightly decreased. The increase of alcohol (ethanol and isopropanol) content also enhanced total flux, but the selectivity reduced prominently. The phenomena indicated that a relatively ideal effect had been achieved.