Good news! Desalination is salvation!
"... With an innovative material design, the Yale and Nanjing researchers have developed a reverse osmosis membrane that not only desalinates water but is also resistant to chlorine as well as fouling. Rather than using the industry gold standard of polyamide to develop these membranes, the researchers instead used polyester. The choice of material is critical, as this polyester membrane allows for substantial water permeability, has a high rejection for sodium chloride and boron, and a complete resistance toward chlorine. The ultrasmooth, low-energy surface of the membrane also outdoes polyamide membranes in preventing fouling and mineral scaling.
Further, the team designed the membranes so that they could be easily adopted by the industry. ..."
From the editor's summary and abstract:
"Editor’s summary
Reverse osmosis membranes have been dominated by polyamide chemistry, which has sufficient performance in terms of water permeability and salt rejection but is vulnerable to degradation in the presence of chlorine or other strong oxidants. Polyesters are not typically used for water filtration membranes because they suffer from hydrolytic degradation when immersed in aqueous solution. Yao et al. show that the polymerization of 3,5-dihydroxy-4-methylbenzoic acid with trimesoyl chloride yields a polymer membrane with impressive resistance to hydrolytic degradation in acidic or basic conditions (up to pH 9) and a complete resistance to chlorine. ...
Abstract
Thin-film composite reverse osmosis membranes have remained the gold standard technology for desalination and water purification for nearly half a century. Polyamide films offer excellent water permeability and salt rejection but also suffer from poor chlorine resistance, high fouling propensity, and low boron rejection. We addressed these issues by molecularly designing a polyester thin-film composite reverse osmosis membrane using co-solvent–assisted interfacial polymerization to react 3,5-dihydroxy-4-methylbenzoic acid with trimesoyl chloride. This polyester membrane exhibits substantial water permeability, high rejection for sodium chloride and boron, and complete resistance toward chlorine. The ultrasmooth, low-energy surface of the membrane also prevents fouling and mineral scaling compared with polyamide membranes. These membranes could increasingly challenge polyamide membranes by further optimizing water-salt selectivity, offering a path to considerably reducing pretreatment steps in desalination."
No comments:
Post a Comment