Multifunctional electrospun polysulfone nanofibrous membranes incorporating functional inclusions for efficient complex oil–water separation
This dissertation aimed to developed electrospun nanofibers (ENs) using polysulfone (PSU) as based polymer, with and without polyvinylpyrrolidone (PVP), for oily wastewater treatment. Nanoparticle incorporation (TiO₂, ZnO, and Ag) in PSU (M-series) and PSU/PVP (MPseries) ENs, generated rough fibers with diameters in ~279–660 nm range, markedly enhanced thermal stability with char yield increased from ~4.8% to 67.6% at ~1000 °C. The surface wettability of the ENs was tuned, with M-series ENs becoming strongly hydrophobic and underwater oleophobic (water contact angle ≈138–150°; underwater oil contact angle ≈130–160°), and MP-series ENs exhibiting superhydrophilic/underwater oleophobic behavior (underwater oil contact angle ≈140–160°; water uptake time ≈1–several s). These tailored surface properties enabled efficient gravity-driven emulsion separation, with water-in-oil membranes achieving fluxes up to 1333 L·m⁻²·h⁻¹ and water rejection of ≈92–98%, where higher nanoparticle loading increased water rejection (𝑟=0.71) but reduced flux (𝑟 = −0.833), while oil-in-water membranes delivered fluxes of ≈338–481 L·m⁻²·h⁻¹ and oil rejection of ≈83–87%. Cyclic filtration tests showed progressive fouling, with M7 exhibiting the most stable water-in-oil performance over 10 cycles and MP4 retaining ≈67% oil rejection after 5 oil-in-water cycles. Beyond emulsion treatment, M-series ENs showed minimal changes in contact angles under harsh conditions, indicating good structural stability, while selected MP-series ENs (MP2, MP4, MP6, MP8) achieved ≈95–98% methylene blue removal within 90 min, demonstrating dual-function separation and adsorption capability. Overall, this study demonstrates the versatility of electrospinning in producing tunable PSU ENs, where PSU, PVP, and nanoparticle selection can alter overall ENs properties, and tune their surface toward different emulsion types.
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