Date | Feb 24, 2017:
Researchers are finding new ways of extracting uranium from sea water. The research may help the countries that lack resources to harness nuclear power from the oceans.
Since long, scientists have known that sea water contains dissolved uranium which combines chemically with oxygen to form uranyl ions with a positive charge.
How is uranium extracted?
To extract the uranyl ions, the scientists dip plastic fibers containing a compound called amidoxime into seawater. The uranyl ions stick to the amidoxime.
Once the strands are saturated, the plastic is chemically treated to free the uranyl, which then has to be refined for use in reactors the way it is done for ores derived from a mine.
What are the variables that decide how practical is the approach?
There are three main variables that help in deciding how practical the approach is:
- How much uranyl sticks to the fibres
- How quickly ions can be captured
- How many times the fibers can be reused
Researchers from the Stanford University in the US improved on all the three variables: capacity, rate and reuse.
They were able to create a conductive hybrid fiber by including carbon and amidoxime. They sent pulses of electricity down the fiber and altered the properties of the hybrid fibre so that more uranyl ions could be collected.
The lab tests that compared Stanfords amidoxime-carbon hybrid fibers with the presently available amidoxime fibres, was overseen by Postdoctoral scholar Chong Liu.
Tests conducted
The first thing she tested was how much uranyl each type of fiber could hold before reaching saturation.
The results showed that by the time the standard amidoxime fiber became saturated, Stanford's amidoxime-carbon hybrid fibers had already adsorbed nine times as much uranyl and were still not saturated.
The tests showed that the electrified fiber caught three times as much uranyl during an 11-hour test using seawater from Half Moon Bay, about an hour from Stanford and had three times the useful lifespan of the standard amidoxime.
Why were we not extracting uranium from the sea water before?
Trace amounts of uranium exists in seawater; however, efforts to extract that critical ingredient for nuclear power has resulted in production of insufficient quantities to make it a viable source for those countries that lack uranium mines.
A practical method for extracting that uranium, which produces higher quantities in less time, could help make nuclear power a viable part of the quest for a carbon-free energy future.
"Concentrations are tiny, on the order of a single grain of salt dissolved in a litre of water," said Yi Cui, a materials scientist at Stanford University in the US, according to PTI.
"But the oceans are so vast that if we can extract these trace amounts cost effectively, the supply would be endless," said Cui.
According to the scientists, a practical way to extract uranium from seawater is required to reduce the energy insecurity of nations that depend on nuclear power but lack uranium within their own borders.
The research was published in the journal Nature Energy.
(Source: http://indiatoday.intoday.in/)