Dual-Layer PVA-HNT/PTFE Membranes for Boosted Antiwettability and Stability in Membrane Distillation

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Membrane distillation (MD) requires membranes with high anti-wettability and stability for practical applications.
• Existing membranes often suffer from wetting and fouling, limiting their performance and lifespan.

Purpose of the Study:

• To fabricate and evaluate a novel hydrophilic-hydrophobic dual-layer membrane for enhanced MD performance.
• To investigate the effect of halloysite nanotube (HNT) loading on membrane properties and performance.

Main Methods:

• Fabrication of dual-layer membranes using poly (vinyl alcohol)/halloysite nanotube (PVA-HNT) and polytetrafluoroethylene (PTFE) layers.
• Characterization of membrane properties, including water transport and anti-wettability.
• Performance evaluation in MD using saline solutions and landfill leachate, assessing flux, salt rejection, and fouling resistance.

Main Results:

• The optimized dual-layer membrane (5 wt% HNT) achieved a stable water vapor flux of 7.6 kg/m²·h and >99.95% salt rejection.
• The dual-layer membrane demonstrated superior resistance to pore wetting compared to pristine PTFE membranes.
• Significant improvements in antifouling properties were observed, with a 15.3% flux decrease over 50 hours versus 70.5% for PTFE.

Conclusions:

• The developed hydrophilic-hydrophobic dual-layer membrane offers enhanced anti-wetting and anti-fouling capabilities for MD.
• HNT incorporation in the PVA layer provides tunable water transport and improves overall membrane stability.
• This novel membrane design presents a promising solution for challenging water treatment applications using MD.