Orderly stacked 3D-nanohelices interlayer boosts performance of reverse osmosis membranes for effective water purification

Reverse osmosis (RO) membrane with high water permeance and selectivity is highly desirable for effective water purification. However, current RO membranes are typically limited by the trade-off phenomenon between water permeance and selectivity. In this study, we first synthesized a 3D nanohelices with nanoscale gaps spacing, then constructed high-performance RO membranes by incorporating the 3D nanohelices as an interlayer. The 3D nanohelices-interlayered RO membrane exhibited ultra-high pure water permeance (∼3.6 ​L ​h −1 ​m −2 ·bar −1 ) and outstanding NaCl rejection (∼98.7 ​%), outperformed the performance of current available RO membranes. Importantly, the 3D nanohelices-interlayered RO membrane demonstrated superior removal of neutral small-molecule nitrosamine pollutants (∼69.9 ​%, ∼87.6 ​%, ∼89.9 ​% and∼95.0 ​%), including N -nitrosodimethylamine, N -nitrosomethylethylamine, N -nitrosopyrrolidine, and N -nitrosodiethylamine, compared to the control (∼46.8 ​%, ∼79.0 ​%, ∼86.7 ​% and ∼93.2 ​%). We revealed that the gutter effect induced by the 3D nanohelices, which shortened the water transport pathway (nano-gaps served as transport channels for water molecules), was the primary mechanism behind the enhanced water permeance of the 3D nanohelices-interlayered RO membrane. The steric hindrance effects of the polyamide layer and the nanoscale selective gaps within the 3D nanohelices synergistically governed the RO membrane rejection of salts and small-molecule pollutants. Our study provides a promising strategy for the rational design of RO membranes for highly effective water purification. • 3D-nanohelices interlayer delivers ultra-high RO membrane water permeance. • 3D-nanohelices create nano-gap channels, shortening water transport pathways. • The membrane effectively removes neutral nitrosamine pollutants (95.0 ​%). • Synergistic steric hindrance and nano-scale gaps ensure selective solute rejection.