Investigation of alumina nanoparticles role on the critical flux and performance of polyvinyl chloride membrane in a submerged membrane system for the removal of humic acid

In this work, the polyvinyl chloride/alumina (PVC/Al2O3) ultrafiltration (UF) nanocomposite membranes were prepared with different amounts of Al2O3 within a range of 0–2 wt.%. Neat PVC and optimum nanocomposite membranes were evaluated in a submerged membrane system for the removal of humic acid (HA). The Fourier transform infrared (FTIR) spectroscopy confirmed the presence of hydroxyl group (OH) on the surface of the PVC nanocomposite membrane. Results revealed that the nanocomposite membrane with 1.5 wt.% of Al2O3 nanoparticles has the highest value in porosity and hydrophilicity when compared to other samples. The results obtained from the field emission scanning electron microscopy (FE-SEM) images showed that as Al2O3 was added to the membrane structure, more pores and larger pores were formed on the membrane surface. A higher critical flux was obtained by the PVC/Al2O3 (1.5 wt.%) nanocomposite membrane due to change in the surface characteristics. Antifouling analysis under subcritical conditions for neat PVC membrane showed that the main portion of the total fouling ratio was irreversible fouling ratio (IFR), while the nanocomposite membrane with 1.5 wt.% of Al2O3 nanoparticles significantly decreased IFR. Finally, the nanocomposite membrane had a higher HA rejection than the neat PVC membrane.