Fabrication and Enhancing the Water Flux and Antifouling Performance of Polyvinyl Chloride Membrane Using Halloysite/Zinc Oxide Nanocomposite Incorporation

Hypothesis: Poly(vinyl chloride) (PVC)-based ultrafiltration membrane was fabricated and modified through incorporation of halloysite nanotube/zinc oxide (HNT/ZnO) nanocomposite into the membrane matrix. The effect of using the prepared nanocomposite in the membrane structure on the surface hydrophilicity, porosity, water content, surface roughness, separation rate, flux, fouling resistance, and membrane flux recovery was evaluated.
Methods: The HNT/ZnO nanocomposite was synthesized via a co-precipitation method and subsequently characterized using field-emission scanning electron microscopy (FESEM), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), and X-ray diffraction (XRD) analyses. The ultrafiltration membranes were fabricated using the phase inversion technique. The physicochemical and morphological properties of the prepared membranes were investigated by the FESEM, ATR-FTIR, energy-dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM). In addition, membrane porosity, water uptake, surface roughness, contact angle, pure water flux, and flux recovery ratio (FRR) were evaluated.
Findings: The results demonstrated that modification of the membrane with the HNT/ZnO nanocomposite significantly enhanced the surface hydrophilicity and increased the pure water flux by approximately three times compared with the pristine PVC membrane. Increasing the nanocomposite loading up to 0.75% (by wt) improved key membrane properties, including hydrophilicity, porosity, water uptake, and mean pore size, thereby enhancing the overall filtration performance. The highest flux recovery ratio (FRR ≈ 64.4%) was achieved for the modified membrane containing 0.75% (by wt) nanocomposite, whereas further increases in nanocomposite concentration resulted in a decline in FRR values. Moreover, the modified membrane exhibited substantially higher protein solution flux and superior antifouling performance compared with the pristine PVC membrane. Evaluation of membrane performance in milk protein concentration and reuse applications revealed that the modified ultrafiltration membrane possessed higher permeability and greater fouling resistance than the unmodified membrane. These findings highlight the potential of HNT/ZnO-incorporated PVC ultrafiltration membranes for efficient protein separation and sustainable membrane-based wastewater treatment applications.