Polysulfone nanocomposite membranes for water filtration and microcystin removal: Mechanical characterisation and multi-scheme homogenisation analysis

Polysulfone (PSf) membranes containing polyvinylpyrrolidone (PVP) and either cerium dioxide (CeO₂) or laboratory-milled bentonite were investigated through structural characterisation, filtration testing and micromechanical analysis. Six formulations were fabricated by non-solvent-induced phase separation: pristine PSf, PSf/PVP and four nanocomposites with 0.5 or 1.0 wt% filler relative to the casting solution. Characterisation combined microscopy, spectroscopy, diffraction, wettability, water uptake, porosity, flux, fouling, tensile testing and dynamic mechanical analysis (DMA). The incorporation of nano-CeO₂ and nano-bentonite into the PSf/PVP membrane altered the surface morphology, increased surface hydrophilicity, and decreased the total fouling ratio. The PSf/PVP 1 wt% bentonite membrane exhibited the highest water uptake (74.67%) and the highest pure water flux (~230 L m −2 h −1 ), indicating enhanced affinity toward water and improved water filtration performance. Young's modulus ranged from 20.9 MPa (PSf/PVP) to 84.1 MPa (PSf/PVP with 1.0 wt% bentonite). The highest total microcystin removal, 76.36%, was achieved with 0.5 wt% bentonite. The storage modulus (E′) ranking of the samples, measured by DMA, remained unchanged over 25–120 °C, and each sample retained 83.5–84.3% of its 25 °C value at 120 °C. Seven analytical approaches were compared using the measured PSf/PVP tensile modulus as an effective matrix reference. At nominal filler fractions, spherical Mori–Tanaka estimates were 21.08–21.92 MPa, compared with measured nanocomposite tensile moduli of 25.63–84.07 MPa. Combined with FTIR evidence and bentonite swelling, these results are consistent with chemical interphase formation and swelling-induced crosslinking, rather than classical load transfer, as the likely dominant stiffening mechanisms.