Flux improvement, rejection, surface energy and antibacterial properties of synthesized TiO2-Mo.HNTs/PVC nanocomposite ultrafiltration membranes

Abstract

The present work demonstrates the preparation of modified halloysite loaded with titanium dioxide (TiO₂) nanoparticles and its use as a nanofiller in a poly(vinyl chloride) (PVC) hybrid ultrafiltration (UF) membrane for advanced water treatment. Modification of raw halloysite nanotubes (rHNTs) with 3-aminopropyltriethoxysilane (APTES) was performed, after which TiO₂ nanoparticles were synthesized using titanium(IV) isopropoxide (TIP) solution on the surface of the modified HNTs (Mo.HNTs) using the sol–gel method. Novel hybrid UF membranes (TiO₂-Mo.HNTs/PVC) were prepared by blending of TiO₂-Mo.HNTs nanofiller in different concentrations using a classical phase inversion method. Pure water flux of the hybrid UF membrane (197.5 ± 3.6 L m⁻² h⁻¹ in 2 wt% hybrid UF membrane) improved consistently with an increasing amount of nanofiller in the membrane matrix. The hydrophilicity of the membrane samples increased (contact angle as low as 68.8° ± 5.6° in 3 wt% hybrid UF membrane) and interfacial surface free energy was also high (−ΔG_SL 98.22 mJ m⁻² in 3 wt% membrane), as compared to the membrane without nanofiller. The rejection of BSA and HA by all TiO₂-Mo.HNTs/PVC (1–3 wt%) membranes was greater than 80%. TiO₂-Mo.HNTs played an important role in stopping pollutants during membrane filtration; and antibacterial activity of the TiO₂-Mo.HNTs/PVC hybrid UF membranes against E. coli was high (95–97.5% in 2 wt% and 3 wt% hybrid membrane). Thus TiO₂-Mo.HNTs played an important role in the separation processes.