Tailoring the crumpled structures of a polyamide membrane with a heterostructural MXene-TiO2 interlayer for high water permeability

Thin-film composite (TFC) nanofiltration (NF) membrane having excellent permeability and desired rejection is needed for water reuse and desalination. However, it remains a tremendous challenge to boost permeability while sustaining the rejection of the membrane. Herein, a novel TFC NF membrane possessing a thin and crumpled polyamide (PA) selective layer was fabricated using heterostructural MXene-TiO2 as interlayer through a conventional interfacial polymerization (IP) reaction. The heterostructural MXene-TiO2 was obtained by the in situ MXene oxidation with peroxymonosulfate (PMS), which effectively regulated the nanostructure of the interlayer and avoided the over-stacking of the nanosheets, promoting the rapid transport of water molecules. Moreover, the large specific area and numerous edges of MXene-TiO2 boosted the adsorption and release of amine monomers on the substrates, facilitating the crumpled structure formation. In this way, the obtained membrane with 30.25 nm in thickness achieved a 98.29 % rejection for MgSO4 and an enhanced water permeance of 11.10 L m−2 h−1 bar−1, about 2.5 times that of TFC0 NF membrane. Our work presents a novel approach of feasibility to engineer a TFC NF membrane with outstanding performance for water treatment.