Long-term stability of PVDF-SiO2-HDTMS composite hollow fiber membrane for carbon dioxide absorption in gas–liquid contacting process

Hybrid polyvinylidene fluoride-silica-hexadecyltrimethoxysilane (PVDF-SiO2-HDTMS) membranes were fabricated via a non-solvent-induced phase-inversion method to create stable hollow-fiber membranes for use in the membrane contact absorption of carbon dioxide (CO2). The surface properties, performance characteristics, and long-term performance stability of the prepared membranes were compared and analyzed. The outer surfaces of the prepared membranes were superhydrophobic because of the formation of rough nanoscale microstructures on the surfaces and their low surface free energy. The addition of inorganic nanoparticles improved the mechanical strength of the PVDF-SiO2-HDTMS. Long-term stable operation experiments were carried out with a mixed inlet gas (CO2/N2 = 19/81, v/v) at a flow rate of 20 mL/min. The absorbent liquid in these experiments was 1 mol/L diethanolamine (DEA) at a flow rate of 50 mL/min. The mass transfer flux of CO2 through the PVDF-SiO2-HDTMS membrane decreased from an initial value of 2.39 × 10-3 mol/m2s to 2.31 × 10-3 mol/m2s, a decrease of 3% after 20 days. The addition of highly stable and hydrophobic inorganic nanoparticles prevented pore wetting and structural damage to the membrane. The PVDF-SiO2-HDTMS membrane was found to have excellent long-term stable performance in absorbing CO2.