Thickness-controlled polyamide membranes via centrifugal thin-film deposition for improved fouling and high-recovery performance

Nanofiltration for desalination and water reuse demands fouling-resistant and high-recovery operation, but is often constrained by permeability–selectivity trade-offs and heterogeneous polyamide growth during interfacial polymerization (IP). Here, we introduce centrifugal thin-film deposition (CTFD) as a controllable aqueous-phase delivery step that spreads piperazine uniformly before polymerization with trimesoyl chloride, limiting monomer infiltration into the porous support and suppressing nonuniform film growth. Molecular dynamics simulations show centrifugal confinement of piperazine near the reaction zone, consistent with experimentally improved film uniformity. CTFD produces ~10–50 nm polyamide layers with lower roughness (Ra ~40–45 nm) than a conventional membrane (Ra ~90 nm). The optimized membrane (0.1 wt.% piperazine; 3.198 kg m/s2) delivers ~136 LMH flux and 94.3% Na2SO4 rejection at 6 bar, fully recovers flux after hydraulic cleaning of sodium alginate fouling, and maintains >85% Na2SO4 rejection at high recovery with higher flux. This work offers an effective strategy to tune polyamide layer formation and transport resistance under sulfate-rich nanofiltration conditions where high permeability, fouling reversibility, and high-recovery operation are prioritized.