Membranes with ZIF-8 regulated MXene nanosheet stacks for efficient molecular sieving.

Thin film nanocomposite (TFN) membranes synthesized by introducing nanofillers into a polyamide layer have attracted increasing attentions. However, due to the aggregation of the nanofillers, the fabricated TFN membranes inevitably suffer from a reduced stability. In this work, a novel nanofiltration (NF) selective layer with in-situ formed ZIF-8 was fabricated by an integrated vacuum filtration and interfacial polymerization (IP) method. The d -spacing of MXene nanosheets could be well tailored by controlling the content of in-situ formed ZIF-8 nanoparticles, thus optimizing the surface morphology and chemical composition of the as-prepared NF membrane. The highly hydrophilic MXene nanosheets and controllable ZIF-8 size enabled the molecular sieving ability of the selective layer. Compared with the pristine thin film composite membrane, the optimal membrane exhibited an excellent pure water permeability up to 40.8 L m−2 h−1 bar−1 while maintaining high rejections (>99.0 %) for Congo red, reactive blue 19, xylene brilliant cyaninG250 and methyl blue, respectively. Furthermore, the membranes preserved low salt rejections for Na 2 SO 4 , NaCl, MgSO 4 and MgCl 2. This novel fabrication strategy provides new insights to augment the interlayer distance of 2D nanosheets and broadens the prospects to employ nanofillers inside a membrane matrix for efficient dye/salt separation. [Display omitted] • 2D MXene nanosheets were supplied as nanofillers and blockers on membranes surface though a 0D/2D heterojunction structure. • The d-spacing of MXene were further turned by an in-situ growth of ZIF-8 nanoparticles. • The aggregation of ZIF-8 nanoparticles was avoided. • The membranes exhibit excellent separation performance for dye/salt mixtures. [ABSTRACT FROM AUTHOR]