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Improving Uranium Extraction From Seawater, Inspired by Shrimp
New submitter Celarent Darii writes "Prospects for harvesting Uranium from seawater turned interesting by using shrimp shells as a sort of catalyst."
Researchers at ORNL presented their findings from a test of a chitin net for harvesting Uranium at the ACS fall meeting. From the ORNL press release: "In a direct comparison to the current state-of-the-art adsorbent, HiCap provides significantly higher uranium adsorption capacity, faster uptake and higher selectivity, according to test results. Specifically, HiCap's adsorption capacity is seven times higher (146 vs. 22 grams of uranium per kilogram of adsorbent) in spiked solutions containing 6 parts per million of uranium at 20 degrees Celsius. In seawater, HiCap's adsorption capacity of 3.94 grams of uranium per kilogram of adsorbent was more than five times higher than the world's best at 0.74 grams of uranium per kilogram of adsorbent. The numbers for selectivity showed HiCap to be seven times higher."
It's not economically feasible now, but the energy balance works out. Even with the previous method that was only 1/5th as efficient, you got much more energy out of the uranium than was required to collect it.
Seawater moves around, and the process still isn't that efficient, so you wouldn't have any problems with decreased concentration.
The reason this is valuable is not so much that it's economical today, as that there's enough uranium in the ocean to provide all our electricity needs for millions of years.
30 to 150 million cubic metres per second. So 12 minutes of Gulf Stream flow would contain enough uranium to supply our present needs for a year.
Though if you could tap the entire Gulf Stream you'd have another source of energy at hand...
Wikipedia says there's 3.3 mg uranium per m^3 of seawater and the volume of the world's oceans adds up to 1.3*10^18 m^3, which means that there's 4.4*10^12 kg of uranium in the oceans, or roughly 400 kg per human in a world with 10 billion humans. That's a lot of uranium...
I don't suppose much is known about the rate at which it replenishes, but I bet scientists will be able to find out about that long before we begin to see measurable depletion of seawater uranium on a global scale.
However, rivers bring more uranium into the sea all the time, in fact 3.2x10^4 tonne per year.
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