Water vapor condensation and collection by super-hydrophilic and super-hydrophobic VACNTs

Abstract

Vertically Aligned Carbon Nanotubes (VACNTs) are well known for their easy production and great modification possibilities, such as oxidation and exfoliation. Some functionalization methods can quickly change carbon nanotubes wettabillity from super-hydrophobic to super-hydrophilic. These last ones have great potential for fog harvesting or other humid gas mixture harvesting. In this work, we used these carbon nanotubes features to develop a super-hydrophobic/super-hydrophilic patterned surface to collect water droplets from humid air. This structure has been designed to biomimic the Stenocara beetle one. In this work we show that water condensation happens on self-cleaning super-hydrophobic surface and then the droplets are pumped by the super-hydrophilic surface. The super-hydrophobic surface was made by deposition of polyethylene on pristine VACNTs/steel screen. The super-hydrophilic surface was fabricated by deposition of functionalized VACNTs on carbon fiber felt. We performed the water collection measurement into a homemade chamber with fog-like humidity control. The best result reached was about 30 (L/m2)/h under controlled conditions.