Fabrication and Development of Polysulfone/Silica Nanoparticle Hollow Fiber Membrane Contactor for Gas Dehydration

Abstract

The wetting phenomenon is an undesirable characteristic of membrane contactors utilized for gas absorption applications. In this research, polysulfone hollow fibers (PSF) modified by silicone rubber coating (PDMS) loaded with hydrophobic silica nanoparticles (SiO₂) were studied as membrane contactors in order to dehumidify the feed gas using diethylene glycol (DEG) as the sorbent liquid. The study aimed to evaluate how the addition of nanoparticles influenced the membrane's structure, hydrophobicity, roughness, and separation performance, particularly flux and efficiency. Findings revealed that surface modification raised the contact angle pressure of water and DEG from 72° to 154° and 58° to 127°, respectively, and enhanced the liquid entry pressure of water and DEG from 6.1 to > 10 bar and 3.7 to 6 bar, respectively. The effect of liquid velocity on water vapor absorption flux was minimal, indicating no mass transfer resistance in the liquid phase. However, increased gas phase velocity significantly improved absorption flux and efficiency. Initially, the neat membrane had a higher absorption flux due to its effective porosity, but its performance dropped over time, failing by day 20. The results of the stability test demonstrated that a wetting ratio ranging from 1% to 2%, achieved after 11 to 16 days, led to a reduction in flux by 30% to 55%. Conversely, the optimum silicone rubber-coated membrane loaded with silica nanoparticles maintained a wetting ratio under 1% and showed more stable flux with respect to the reference membrane for 42 days (a 6 weeks test) due to enhanced surface characteristics. The optimum membrane depicted a flux of 1.8 × 10⁻² mol/m² s, which is 1 to 2 orders of magnitude higher than the previous studies. It was anticipated that, by modifying the surface properties of the contact membrane, the long-term performance of the contact membrane would be enhanced to have a significant growth compared to the pure membrane and the open literature reports. The results show that the applied technique for fabricating hollow fiber membrane contactors can be a promising technique in gas conditioning processes.