Antifouling hybrid ultrafiltration membranes with high selectivity fabricated from polysulfone and sulfonic acid functionalized TiO₂ nanotubes

In this work, antifouling hybrid ultrafiltration membranes were manufactured using polysulfone (PSf) and sulfonic acid functionalized TiO₂nanotubes (TNTs-SO₃H). TNTs-SO₃H were first synthesized by performing a coupling reaction between 3-mercaptopropyl trimethoxysilane and hydroxyl groups on TiO₂nanotubes with in situ oxidation using 30 wt% H₂O₂solution. Hybrid membranes containing TNTs-SO₃H up to 5 wt% were then prepared from the blend solutions of PSf/TNTs-SO₃H via a non-solvent induced phase separation (NIPS) method. The hybrid membranes were characterized using contact angle, Fourier transform infrared spectroscopy, scanning electron microscopy and surface zeta potential studies. The antifouling capability of hybrid membranes with bovine serum albumin and humic acid (HA) as model foulants were investigated in detail. Hybrid membranes exhibited better water permeability and antifouling performance during filtration of foulant solutions. The ultrafiltration of HA solutions of different concentrations was carried out at pH = 7 and 1 bar feed pressure, with the removal of HA from aqueous solution being controlled through the charged behaviour, porosity and exclusion of HA by hybrid membranes. The maximum removal of HA from 20 ppm aqueous solution was achieved using the hybrid membrane MTS-5 containing 5 wt% TNTs-SO₃H.