9 ms·
Hydrophilic disc uses solar power to separate salt from water
- beat 7y agoOne cool thing about this is that it looks inexpensive and simple, as well as functional. If a square meter can generate enough clean water for a person per day, islands of it could support entire cities.
- pg_is_a_butt 7y agoconsidering frances solar road crumbled after 3 years, you'll probably be rebuilding an entire island at least once per year and after most big storms... those workers are going to be thirsty.
- jbob2000 7y agoThis doesn't make for a good drinking water, this creates distilled water that would drain your body of minerals if you drank it. You now need to expend energy to gather those minerals from somewhere else and then put them in the water. Is the energy spent gathering those minerals more than other desalination processes?
- option_greek 7y ago>You now need to expend energy to gather those minerals from somewhere else and then put them in the water Did you mean the white stuff coming out :)
- jbob2000 7y agoIs that just salt? Or a heterogeneous mixture of salt and minerals? You want just the minerals, no salt. How do you separate the salt from the minerals in that "white stuff"?
- simongr3dal 7y agoMost likely the NaCl crystals will have grown larger than the other salts and minerals, so the right progression of sieves will separate it well enough.
- ncmncm 7y agoSalt is a mineral. You need it. There are minerals in your food. You don't need to get them all from your water. Anywhere is as good as anywhere else.
- DennisP 7y agoDoes reverse osmosis retain the minerals? And wouldn't the minerals in food compensate for their lack in water?
- jbob2000 7y agoNo, reverse osmosis filters out most minerals. But reverse osmosis filters aren't always used for drinking water. And yes, minerals in food can compensate.
- wrycoder 7y agoPeople pay good money for “sea salt” to use on their food. That’s just the dried residue from this process, assuming clean sea water to begin with. It’s common to add a bit of salt and Epsom salts to water when brewing - the harder water improves the taste. You get your minerals from food, not water. I doubt your premise about leaching body minerals by drinking distilled water (or rainwater!).
- HillaryBriss 7y ago> People pay good money for “sea salt” true. and if the salt produced by this process if free of micro plastics, people might pay even more
- driverdan 7y agoThat's an urban legend. We get nutrients and minerals from the food we eat.
- DanBC 7y agothe World Health Organistion seems to think that it's important (but also reasonably easy to fix). https://www.who.int/water_sanitation_health/dwq/nutrientschap12.pdf https://www.who.int/water_sanitation_health/dwq/nutrientscha...
- robocat 7y agoThe first sentence is probably true, the second seems false. "Results of experiments in human volunteers evaluated by researchers for the WHO report (3) are in agreement with those in animal experiments and suggest the basic mechanism of the effects of water low in TDS (e.g. < 100 mg/L) on water and mineral homeostasis. Low-mineral water markedly: 1.) increased diuresis (almost by 20%, on average), body water volume, and serum sodium concentrations, 2.) decreased serum potassium concentration, and 3.) increased the elimination of sodium, potassium, chloride, calcium and magnesium ions from the body"
- sitharus 7y agoA very large number of people get their water from captured rain water stored in tanks. I do myself. It's not mineral-free but it's certainly very low in dissolved minerals. I appear to be alive, as do many others.
- jjtheblunt 7y agohttps://en.wikipedia.org/wiki/Solar_still https://en.wikipedia.org/wiki/Solar_still is a lower tech solar solution?
- goda90 7y agoOne cool application of solar stills is when you can't find any liquid water, no matter how salty or dirty, but you can cut up parts of plants and seal them in plastic to collect the moisture from the plants. Obviously not scalable, but it can be a useful survival technique.
- aidenn0 7y agoActually the Navy survival kit still seems to even have similar space efficiency if a 1/3m^2 footprint allowed for 2.4L per day. That would translate to 7.2L per M^2 per day which is right around the 6-8L mentioned in the article.
- Retric 7y ago“This device can produce six to eight liters (1.6 to 2.1 gal) of clean water per square meter (of surface area) per day” That’s really bad from a density standpoint. You’re talking ~8,000 gallons per day per acre of land. Solar powered reverse osmosis is something like 1/500th the space. If the can get installed costs below 1$ per square meter it might be interesting, but even just land costs are likely to be an issue.
- SCAQTony 7y agoBut what do you do with the salt and brine that is toxic to soil used in the farming? The wind will scatter the salt in all directions.
- wbl 7y agoYou dump the brine into well-mixed ocean areas.
- JBReefer 7y agoYou sell it, salt is required for mammals.
- ryanmarsh 7y agoFunny how our bodies need water and salt, both are in such abundance but in a problematic way. Max recommended salt intake is less than 1 teaspoon per day. You need 2 liters of water per day. There's nearly 6 teaspoons of salt in 1 liter of sea water. That's quite a bit of excess salt. Kind of a bummer really. Wish we had a gland that got rid of excess salt then we could just drink sea water.
- umvi 7y ago> Wish we had a gland that got rid of excess salt then we could just drink sea water. If such a gland existed, it would probably require a lot of energy to work. Plus, what would the gland do with all of the salt it is filtering just send it to your kidneys/bladder? I'm imagining kidney-stones formed from all the excess salt your body is trying to get rid of
- inflatableDodo 7y agoReminds me of dye chromotography, I wonder if you can get different salts to turn up at different places on the edge? Might be able to get useful concentrations of lithium out of it that way.
- wollstonecraft 7y agoHydrophilic anything in the environment quickly fouls to hydrophobic.
- ncmncm 7y agoEven when supplied via wicking?
- tom_mellior 7y agoDo I understand it correctly that this doesn't actually produce liquid water but only somewhat more humid air in the general area above the device? I wonder how much additional effort it takes to actually get the water into a container.
- carapace 7y agoTo me it looked like moisture was condensing inside the column and maybe collecting in the bottom.
- tom_mellior 7y agoYeah, I saw the condensation in the column, but since that's where the salt water comes in I figured it would be related to that. The article talks about "steam that builds up on the disc", which I understood to mean its upper surface. The university's press release at https://www.monash.edu/news/articles/water-solutions-without-a-grain-of-salt https://www.monash.edu/news/articles/water-solutions-without... says: "Researchers created a disc using super-hydrophilic filter paper with a layer of carbon nanotubes for light absorption. A cotton thread, with a 1mm diameter, acted as the water transport channel, pumping saline water to the evaporation disc. The saline water is carried up by the cotton thread from the bulk solution to the centre of the evaporation disc. The filter paper traps the pure water and pushes the remaining salt to the edges of the disc." My best guess at what this means is that some of the water is turned into vapor (not really steam at 100 C, I guess?) and that this evaporation drives the capillary effect that keeps bringing in new water. Some other part of the water, the part that "the filter paper traps", could then drip out into the column. Maybe? Or maybe this prototype is really more about just demonstrating that salt can be collected, and doesn't care about capturing the water. Here's the original article, paywalled at UKP 42.50: https://pubs.rsc.org/en/content/articlelanding/2019/ee/c9ee00692c/unauth#!divAbstract https://pubs.rsc.org/en/content/articlelanding/2019/ee/c9ee0...