Advanced multi-functional regenerative and self-healing tight ultrafiltration membrane for dye/salt wastewater efficient purification

Membrane fouling and membrane damage during membrane operation significantly reduce the permeate flux and separation efficiency, and the preparation of ultrafiltration membranes with renewable and self-healing properties is particularly critical for the sustainable recycling of water resources. Herein, we report a novel tight ultrafiltration membrane, which achieves self-healing properties by incorporating modified β-cyclodextrin (β-CD) monomers into the membrane, forming hydrogel by utilizing UV-induced graft polymerization and covalently binding to the membrane substrate, and then utilizing modified Azo to self-assemble into the hydrophobic cavities of the β-CD via host–guest interactions to construct host–guest chemistry to achieve regenerative anti-fouling properties. In addition, the chemical damage caused by UV-induced during the regeneration process is somewhat avoided by the modified azobenzene (Azo) and β-CD. Taking the renewing membrane as an example, the regeneration test shows that the membrane still has high flux recovery (FRR = 92.5 %) and stable separation performance after three regenerations. Physical self-healing tests showed that the dye/salt rejection recovery of the renewing membrane was greater than 95 % for all four common dyes and salts. In the case of chemical damage, a new peak appears in the XPS at 165.4 eV, demonstrating of the reliability of the actual self-healing of chemical damage. Meanwhile, the results of the mechanical properties of the renewing membrane before and after damage show that the membrane can still maintain high mechanical properties after physical self-healing has occurred. This novel anti-fouling and self-healing tight ultrafiltration membrane for practical high salinity textile wastewater separation has a broad application prospect.