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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."
Yes, there is lots of uranium around. But it's locked up in mines, in places such as Niger which are unstable. Japan investigated this seawater uranium source because it wanted a stable source of uranium - one that would not depend on vagaries of geology, mining, and international politics. Because seawater contains approximately the same amount of uranium throughout the world, there is no need to get the uranium - they would let the uranium come to them, via ocean currents. Its a viable idea, even before this newest chitin invention. From what I remember, the cost of ocean uranium recovery was only twice what the market price of uranium was when the Japanese documented this method, and they were confident they could make incremental progress on lowering the cost. I would assume that all of the Japanese research has been cancelled in light of the post-Fukushima madness.
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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