Thin-film composite polyamide membranes are currently used in reverse osmosis (RO) yet they are inherently limited from their poor rejections towards small uncharged pollutants and easily damaged by chemical oxidants used in water treatment. In this work, we show that hydrophobic nanoporous membranes with entrapped nanobubbles layer inside the pores can facilitate pressure- driven desalination with high selectivity and oxidation resistance. Superhydrophobic alumina membrane with 20 nm pore size demonstrated >99.8% rejection of NaCl under the operating pressures of up to 44.8 bar. Unlike polyamide membranes, the membrane exhibits high rejection of small uncharged compounds with >98% for boron and urea and >95% for N- nitrosodimethylamine (NDMA). Desalination performance of the membrane was unaffected by high exposures to chlorine (1000 ppm in 36 hours) and ozone (25 ppm in 1 hour) that compromised the selective properties of polyamide membranes. We also found that reducing thickness to 1 ?m allows the membrane to circumvent the permeability-selectivity trade-off that restricts conventional polyamide membrane. Finally, we demonstrate the scalability of the process for desalination and water reuse using large-area polytetrafluorethylene membranes. Overall, the membranes introduced in this work overcome the limitations in selectivity and chemical resilience that plague current RO membranes, paving the way for more energy efficient, cost-effective, and compact aqueous separations.
This presentation is available to AMTA Members only.
- Duong Nguyen
- University of Colorado Boulder
- AMTA Fellowship Recipients: Advancements in Membrane Research - Part 2, Online
- AMTA Fellowship Recipients Series
- Vapor-Gam Reverse Osmosis, Ultra-Selective, Oxidant-Resistant