Superhydrophobic Surface-Constructed Membrane Contactor with Hierarchical Lotus-Leaf-Like Interfaces for Efficient...

An organic-inorganic polyvinylidene fluoride/polyvinylidene fluoride-silica (PVDF/PVDF-SiO₂) mixed matrix membrane contactor is fabricated via a facile and efficient hydrophobic modification method. The solubility parameters of the PVDF particle are precisely regulated, the PVDF particles are blended with SiO₂ nanoparticles to form PVDF-SiO₂ suspension, and then the suspension is introduced onto the surface of the PVDF substrate by an in situ spin coating strategy. The PVDF particles are partly etched and incorporated to construct the adhesive PVDF-SiO₂ core-shell layer on the PVDF substrate, which results in a more stable PVDF-SiO₂ coating layer on the substrate. The surface structure is precisely regulated by changing the etching morphology of PVDF particles and amount of doped PVDF and SiO₂ particles, forming an integrated porous PVDF-SiO₂ layer and constructing hierarchical lotus-leaf-like interfaces. The resultant PVDF/PVDF-SiO₂ membrane contactors display the relatively regular distribution of pore size with ∼420 nm and excellent hydrophobic property with a water contact angle of ∼158°, which noticeably lightens wetting phenomena of membrane contactors. The SO₂ absorption fluxes can reach as high as 1.26 × 10^-3 mol·m^-2·s^-1 using 0.625 M of ethanolamine (EA) as liquid absorbent. The high stability of the SO₂ absorption flux test indicates the excellent interface compatibility between the PVDF-SiO₂ coating layer and the PVDF substrate. The versatile organic-inorganic layer exhibits super hydrophobic property, which prevents wetting of membrane pores. In addition, the membrane mass transfer resistance (H/K_m) and membrane phase transfer coefficient (K_m) are explored.