Crumple-textured polyamide membranes via MXene nanosheet-regulated interfacial polymerization for enhanced nanofiltration performance

Nanofiltration (NF) membranes based on polyamide (PA) chemistry have been broadly utilized in saline water desalination and advanced treatment of drinking water. The creation of a nanomaterial interlayer between the support and PA film is known as a promising strategy to improve the filtration performance of traditional PA NF membranes. However, an ultrahigh selective PA NF film featuring ultrathin and crumple-like morphology is still in great challenge. Herein, a highly efficient NF membrane with both enhanced water permeance and salt rejections was prepared via a brush-painting MXene-assisted interfacial polymerization (MA-IP) process. An ultrathin and crumple-textured PA film with ~15 nm thickness was constructed on the MXene-painted polyethersulfone support. The effects of MXene painting cycles on the performance of the support and subsequent PA layer were systematically characterized. The presence of the MXene layer increased the hydrophilicity and PIP adsorption of the pristine support, leading to an accelerated IP reaction rate. The resultant NF membranes exhibited rougher surface, greater hydrophilicity, higher electronegativity and denser skin layer. Excellent water permeability of 27.8 ± 2.1 L m⁻² h⁻¹ bar⁻¹ together with satisfactory α(NaCl/Na₂SO₄) of ~480 was obtained for the MXene-interlayered NF membrane, overcoming the trade-off effects between water permeance and salt selectivity. The MA-IP strategy of this work is expected to provide a new approach for fabricating low-pressure NF membranes for brackish water desalination.