NanoH2O is a Los Angeles-based startup that has developed a new membrane material for use in reverse osmosis (RO) desalination. While RO is an established technology, its economic viability hinges on the properties and performance of the membrane.
NanoH2O’s CEO, quoted in this Greentech Media article, put it this way: “A more productive membrane allows less energy to be used and provides higher throughput.”
The company owns at least five U.S. patents and applications relating to its membrane technology, which uses nanomaterials to boost permeability. This is important because a more permeable membrane allows more fresh water through with less pressure from an energy-driven pump.
U.S. Patent No. 8,177,978 (’978 Patent) is entitled “Reverse osmosis membranes” and directed to reverse osmosis membranes incorporating nanoparticles and processes for preparing the membranes. In different embodiments, the nanoparticles are incorporated into various layers of the membrane.
In Figure 1 of the ’978 Patent, RO membrane (10) has nanoparticles (16) dispersed in the aqueous phase layer (14) on the upper surface of the support membrane (12). The organic phase layer (18) interacts with the aqueous layer (14), and polymerization occurs at the interface of these two layers.
According to the ’978 Patent, the nanoparticles release metal species, resulting in improved fouling resistance and increased flux:
In some embodiments, nanoparticles may be selected for their ability to release metal species such as alkaline earth or aluminum ions. Such particles may be dispersed within either the aqueous layer 14 or the organic phase layer 18, or both. Additional nanoparticles may also be present to impact surface properties or further increase performance, for example to improve fouling resistance. . . .By dispersing aluminum releasing nanoparticles 16 in the aqueous or polar solvent 14 and/or organic phase layer 18 before interfacial polymerization, increased flux is often observed, especially when nanoparticles 16 are processed to enhance solubility of metal ions.
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The membrane (10) shown in Figures 2-4 has nanoparticles or other insoluble carriers (16) in difference locations, i.e., in the organic phase / layer (18), in both the aqueous layer (14) and the organic layer (18), and/or in a layer between the aqueous layer (14) and the support membrane (12).
In one embodiment, RO membrane (10) has nanoparticles (22) in the fabric layer (20) that forms the backing of the membrane, making the backing more mechanically robust so it can be made thinner than conventional backings. There are also nanoparticles (16), which may be the same or different from nanoparticles (22), in the discrimination layer (24).
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According to the Greentech Media piece, NanoH20 plans to build a manufacturing facility in China, where its desal technology is badly needed.