Polyamide nanofiltration membranes mediated by mesoporous silica nanosheet interlayers display substantial desalination performance enhancement

Abstract

Recently, thin-film nanocomposite membranes with interlayered structures (TFNi) have demonstrated great promise for breaking the permeance-selectivity trade-off in nanofiltration (NF). Here, we first report the polyamide (PA) nanofiltration membranes mediated by mesoporous silica nanosheet (MSNS) interlayers. According to the characterizations and chemical analysis, it suggested that the inclusion of MSNS greatly affected the PA membrane surface topography and chemical structure, leading to an enhancement in surface roughness, hydrophilicity, and negative charge and a reduction in crosslinking degree and thickness of the PA layer. Ultimately, the fabricated optimal membrane displayed a favorable combination of high water permeance of 22.5 L m−2 h−1 bar−1 (2.5 times higher than pristine PA) and satisfactory Na2SO4 rejection of 97.8 %, superior to most of the TFNi membranes reported so far when compared by NaCl/Na2SO4 permeation selectivity versus water permeance. Additionally, the MSNS aided design endowed the TFNi membranes with drastically improved antifouling property and high operational stability. Also, the structural advantages of MSNS were highlighted by conducting a control experiment with zero-dimensional (0D) silica nanoparticles. This work is expected to stimulate the use of silica-based nanomaterials for preparing high-performance NF membranes for efficient desalination.