Nanosilica-incorporated polyethersulfone-polytetrafluoroethylene dual-layer hollow fibers for direct contact membrane distillation

Abstract

This study advances membrane distillation by innovating a dual-layer hydrophilic-hydrophobic hollow fiber membrane, significantly enhancing vapor transfer and reducing conductive heat loss in direct contact membrane distillation (DCMD). Building on prior research that optimized polytetrafluoroethylene (PTFE) particle size (0.5 µm) and concentration (6 wt%) in polyethersulfone (PES)-PTFE membranes, this research incorporates silica nanoparticles to achieve super-hydrophobization of the outer layer. Concentrations of 0.2, 0.4, and 0.6 wt% silica nanoparticles were assessed for their impact on the membrane's structure and function, using scanning electron microscopy, liquid entry pressure, water contact angle, and mercury intrusion porosimetry. The most effective configuration was found with 6 wt% PTFE and 0.6 wt% silica nanoparticles, achieving a water flux of 18 kg m²/h and a salt rejection rate of 99.99% at 90 °C in DCMD. This integration of silica nanoparticles significantly enhances membrane hydrophobicity and separation efficiency, marking a novel advancement in membrane technology with practical implications. The performance improvement over varying salt concentrations and extended durations suggests the potential of these silica-enhanced membranes in addressing global desalination challenges, opening avenues for further research in nanoparticle-enhanced water purification methods.

Graphical abstract