Thin-film composite membranes with mineralized nanofiber supports for highly efficient nanofiltration

Nanofiltration has exhibited broad application prospects in the field of precise separation attributed to its unique sieving performance for ions and small molecules, high permeation flux and low energy consumption. However, it remains a great challenge for current nanofiltration membranes (NFMs) to improve the permeability while maintaining the high rejection for divalent (or multivalent) ions. In this work, we design and fabricate a novel thin-film composite (TFC) nanofiltration membrane, for which an electrospun polyacrylonitrile nanofiber membrane is adopted as the support after modified by a zirconia mineral layer via surface biomimetic mineralization method, and then an ultrathin selective layer of polyamide (PA) with wrinkled structure is constructed on it via interfacial polymerization. The hydrophilic mineralized nanofiber surface can help to decrease the thickness of the PA layer significantly. Meanwhile, the abundant zirconia particles acting as templates will generate a wrinkled structure for PA layer, providing an improved effective filtration area. Therefore, the resultant NFMs exhibit a high water flux of 38.2 L m−2 h−1 (under 4 bar) accompanied with excellent rejection rate for divalent anions (e.g. 97.6% for SO42−) and cations (e.g. 92.4% for Mg2+). This study could pave an avenue to develop highly efficient NFMs for comprehensive separation applications.