Electrospinning in membrane contactor: manufacturing Elec-PVDF/SiO2 superhydrophobic surface for efficient flue gas desulphurization applications

In membrane contactors, maintaining a high SO2 absorption flux and an excellent wetting resistance are crucial for hazardous gas removal. In this study, we adopted an electrospinning strategy to fabricate highly robust superhydrophobic dual-layer Elec-PVDF/SiO2 composite membrane contactors used for flue gas desulfurization. The composite membrane contactor consisted of a durable and ultrathin three-dimensional (3D) superhydrophobic surface and a porous supporting layer, where the formulation was optimized by regulating the PVDF concentration, solvent ratio and SiO2 particles content in electrospinning solution. The scanning electronic microscopy (SEM), EDS-mapping, water contact angle (WCA) and surface roughness of as-prepared Elec-PVDF/SiO2 composite membrane contactors were conducted to explore the physical and chemical structure. The SiO2 nanoparticles were uniformly loaded in Elec-PVDF/SiO2 composite membrane contactor, and constructed micro-nano dual-coarse lotus-leaf-like morphology, which noticeably elevated surface roughness (Ra). The SiO2 nanoparticles also functioned as hydrophobic modifiers, which boosted the WAC up to 155°. The SO2 absorption fluxes and SO2 removal efficiencies were investigated. In particular, the membrane contactor doped with 20 wt% SiO2 nanoparticles significantly elevated the stability of desulfurization performance. Besides, the membrane mass transfer coefficient (Km) and corresponding membrane mass transfer resistance (H/Km) were explored