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"... A new membrane could provide help, by dramatically improving a water filtering technology already used to clean up pollution from industrial sources and farms, researchers reported last week in Nature Sustainability. If they can be scaled up and commercialized, the authors argue, the new filters could sharply reduce the cost of turning wastewater into safe drinking water. ...
The sale of nanofiltration membranes is already a $1 billion business annually, according to the market research firm MarketsandMarkets. But a challenge for manufacturers has been controlling the range of pore sizes, which limits the membranes’ ability to exclude some contaminants ...
One option for cleaning up this wastewater is using “nanofiltration” membranes, which feature plastic films shot through with holes roughly 1 nanometer across to filter out pollutants such as organic compounds, metals, and microbes. (Desalination plants use even more finely perforated “reverse osmosis” membranes, with holes 0.1 nanometer across, to filter out dissolved salts.)
Now, ... have come up with a way to make membranes with consistent 1-nanometer pores. The researchers started with two polymer building blocks: long, polelike molecules and short, connecting segments. When placed in solution with a porous plastic film, the poles and connector segments lined up on the film. The connectors bonded to specific sites on the poles, creating a sheet with ring-shaped voids, a bit like a chain-link fence. Stacking numerous sheets, the researchers formed a solid membrane. ..."
From the abstract:
"Membrane nanofiltration is widely used in various chemical separation and water purification processes. However, obtaining high water permeance and high solute removal selectivity for achieving energetically efficient precise separation in nanofiltration membranes remains challenging due to their inherent pore heterogeneity. Here we introduce a cinnamate-mediated polymerization method to fabricate nanofiltration membranes with highly homogenized and well-tailored nanopores to address this challenge. Our experimental data and molecular dynamics simulation results show that cinnamate-mediated polymerization can manipulate monomer diffusion and intermolecular void size to create a homogenized and tailored selective layer in a highly homogenized membrane. The obtained membrane exhibited a high water permeance of 104.3 l m−2 h−1 bar−1, which is substantially higher than that of the pristine membrane synthesized without cinnamate mediation, superior molecular sieving ability, excellent salt/dye separation factor and good operational stability, outperforming state-of-the-art membranes. Overall, this work enables the design and fabrication of nanofiltration membranes that combine other mutually exclusive properties for energetically efficient water purification applications towards a sustainable water–energy nexus."
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