Patterned Hybrid Wettability Surfaces for Fog Harvesting

Area of Science:

• Materials Science
• Environmental Science
• Chemical Engineering

Background:

• Fresh water scarcity is a critical global challenge impacting human survival.
• Nature-inspired strategies, particularly fog harvesting by arid organisms, offer potential solutions.
• Superhydrophilic and superhydrophobic patterning is key to efficient water collection from atmospheric moisture.

Purpose of the Study:

• To design and fabricate a composite membrane for efficient fog harvesting.
• To mimic the synergistic water collection mechanisms observed in natural organisms.
• To develop an alternative strategy for mitigating fresh water shortages.

Main Methods:

• Fabrication of a porous polyacrylonitrile (PAN) substrate using non-solvent-induced phase separation (NIPS).
• Creation of a hybrid wettability surface by chemically modifying the PAN substrate with 1H,1H,2H,2H-perfluorooctyltrichlorosilane, using an iron mesh as a mask to create patterned hydrophilic and hydrophobic regions.
• Tuning the hydrophilic/hydrophobic area ratio by adjusting the mesh number of the iron mask.

Main Results:

• The composite membrane exhibited a concave-convex morphology and hybrid wettability.
• Optimized fog harvesting efficiencies of 40.3 and 74.2 mg·cm⁻²·min⁻¹ were achieved at fog yields of 0.05 and 0.1 L·min⁻¹, respectively.
• The fog harvesting process involves efficient condensation, coalescence, and rapid droplet transportation.

Conclusions:

• The developed composite membrane effectively harvests fog, demonstrating significant potential for water resource management.
• The biomimetic design, combining superhydrophilic and superhydrophobic properties, enhances fog collection efficiency.
• This research presents a viable alternative strategy to combat the increasing scarcity of fresh water.