Facile Preparation of Sulfonated Polysulfone Composite Membranes with High Hydrophilicity and Visible-Light Driving Self-Cleaning Performance

The photo-Fenton reaction can efficiently degrade organic pollutants and thus is applied intensively for clearing out membrane fouling. However, the pollutant removal efficiency is greatly limited by the redox cycle rate of Fe²⁺/Fe³⁺ and the rapid recombination rate of the photogenerated electrons and holes. In order to overcome these drawbacks, a sulfonated polysulfone composite membrane was designed and prepared by incorporating titanium dioxide (TiO₂) nanoparticles into a sulfonated polysulfone membrane and sequentially forming β-FeOOHs on the membrane surface. It was found that the synergy of TiO₂ and β-FeOOH enhanced the hydrophilicity and improved the pure water flux of the composite membrane. As a result, the composite membrane exhibited superior separation performance for methylene blue and rhodamine B cationic dyes. The rejection rate was larger than 99.5%, and the pure water flux was larger than 125.7 L m^-2 h^-1, largely surpassing that of nanofiltration membranes. Meanwhile, the composite membrane exhibited an excellent self-cleaning performance, achieving a flux recovery rate over 99.7% after visible-light driving Fenton reaction treatment. The rejection rate still remained above 97.2% after 5 cycles of filtration and recovery, indicating the strong treatment ability of the membrane for dye wastewater.