Incorporating covalent organic framework nanosheets into polyamide membranes for efficient desalination

Incorporating multifunctional fillers into thin film composite (TFC) polyamide (PA) membranes have become a popular approach. Covalent organic framework nanosheets (CON) are expected as ideal fillers in the fabrication of TFC membranes owing to their intrinsic pores with tunable aperture size and large porosity. Herein, we report fabrication of TFC membranes by reacting piperazine (PIP) and trimesoyl chloride (TMC) in the presence of covalent triazine framework nanosheets (CTN) fillers. The incorporation of CTN in PA matrix created extra water channels in the form of pores and interfacial cavities, rendering the resultant PA-CTN TFC membranes ultra-high water flux (23.8 L m⁻² h⁻¹ bar⁻¹), an increase of 5 folds compared to pristine PA membrane and excellent Na₂SO₄ rejection of (>95%). Owing to the hydrophilic nature of CTN, the resultant PA-CTN TFC membranes also displayed higher hydrophilicity and improved anti-fouling properties. The approach in this study may not only offer some guidance on manipulating interfacial polymerization process through incorporating organic framework materials, but also offer some inspiration for the research and development of thin film composite membranes.