#206 - Digital Twin Earth, Private Desalination, Texas oil, Nanocatalysts & a Janus Evaporator
Water Water Everywhere...
Hey Readers,
We have a short list of innovations and the usual dose of some-good, some-bad news to talk about this week. Let’s get into it…
Innovations Roundup
A Janus evaporator made of silver and bamboo fibers
First off - Solar desalination is better because it uses solar energy rather than fossil fuel-powered systems. A prevailing idea for solar based desalination is a device that floats on the surface of water and uses sunlight to heat up, evaporate and separate clean water from the salts in seawater. This in turn requires that one side of the device be super water absorbing i.e. superhydrophilic, with the other side needing to be good at letting water evaporate out, or water rejecting (superhydrophobic). Given the two-faced nature of such a device, they are aptly named after Janus. This latest version of a Janus evaporator comes from the folks at Lanzhou University of Technology in China. They built a contactless 3D Janus evaporator with a structure built by first creating a core made of nickel sponge decorated with silver nanoparticles (Ag-NSPs). This Ag-NSP sponge is then wrapped using bamboo fiber paper (BFP) which serves as the shell.
The superhydrophobic Ag-NSP core absorbs solar light and converts it to heat. This heat helps evaporate the water, without the water fouling the core (because hydrophobic i.e. water rejecting). Meanwhile, the superhydrophilic BFP shell not only provides a larger evaporation area (side surfaces as evaporation surfaces) but also forms a 2D water channel to ensure sufficient water supply. This entire contraption is floating out on the water on polystyrene foam (EPS) which isolates the core photothermal material from bulk water, minimizing heat transmission losses dramatically. The hydrophilic layer is in direct contact with the bulk water, allowing concentrated salt removed during desalination to be rapidly diluted into bulk solutions, thus avoiding the blockage of water transport channels. The hydrophobic layer prevents the upward transport of saline water, effectively inhibiting salt deposition on the hydrophobic photothermal surface. Not bad at all. Now to bring it up to commercial use
Nanocatalysts to remove PFOA by electrocatalysis
Scientists from the University of Rochester have developed new electrochemical approaches to clean up forever chemicals - nanocatalysts. They create these nanoparticles by focusing a laser into a liquid solution and in turn that carves out [NiFe]-layered double hydroxide nanocatalysts, from the solution. They then adhere the nanoparticles to carbon paper that is hydrophilic, or attracted to water molecules. That provides a cheap substrate with a high surface area.
Then in an aqueous electrocatalytic process these NiFe nanocatalysts on hydrophilic carbon fiber paper are immersed in a high concentration solution of Lithium hydroxide. When added to PFOA contaminated water, it completes the electrocatalytic circuit. Thus the nanocatalysts help break the pesky fluoride bond resulting in the complete electrocatalytic defluorination of potassium perfluorooctane sulfonate (PFOS). Once the fluorine bond is broken the lithium hydroxide reacts chemically with the fluorine and otehr ions forming inert easier to remove contaminants.
In Other News
Texas regulators last month approved water rights for a new, 2,500-acre reservoir to meet the growing needs of chemical plants, refineries and other industries on the Gulf Coast. To be clear that’s water rights for fossil fuel plants to use as needed and pollute eventually. Fail!
We’ve talked in the recent past about Catalonia and Spain in general being in a historic drought. So it should come as no surprise that the Catalan government has officially permitted the use of private desalination plants, but only on the grounds that it is proven that they can boost and maintain essential economic sectors. No mention of how they will get drinking water to those most in need though
Finally for this week we wanted to talk about a (literal) moon-shot project - the Digital Twin Earth Hydrology Platform, is an attempt to build a virtual replica of the terrestrial water cycle, combines new high-resolution satellite observations and cutting-edge modeling to build a test environment for the entire earth. That way, we can simulate the bad things to come and use it plan for the consequences. More power to this team of scientists attempting to build this view of the world.
That is it for this Friday, until next week,
Peace!