Lecture notes for actinide chemistry
- Nuclear Energy reactions
- Can change the bad bi-products to things with a longer half life (the bottom right of the periodic table)
- Bunsens idea of using spectroscopy helped to determine whether elements were new or not. Rather than maybe just looking different
- The idea of the lathinites and actinites being similar became a bit of a stumbling block
- Adding electrons to 4f going across lanthinite series. Orbitals are added to the core, they do not become involved in the chemistry, looks like adding a proton to the nucleus
- Gap between +3 and +4 oxidation states is large so +4 is unlikely to exist
- Cerrium has the most stable +4 energy
- The energy levels of 5f and 4f are similar in energy? Can make actinites more lathnite and vice versa?
- 19/10/22 10:05:26
- Plutonium has an ambiguous oxidation state because there is not much potential between ions
- enrichment of Uranium to a nuclear cycle level is hard
- There’s a bottleneck of what to do with decommissioned nuclear warheads and general nuclear related materials
- Radium 1920’s very prevalent, pretty mad. 10 min on previous uses of radium
- 02/11/22 10:04:44
- Need to do some review on radioactivity.
- Most of uranium comes from Canada and Australia
- can make lots of new elements in nuclear reactor, things like Californium.
- Plutonium ground state has valence fluctuations, meaning it’s a weird element,
- Plutonium photos have different number of f electrons (colour changes)
- 07/11/22 14:02:22
- Heavy water is D20 which I assume is deuterium, which surely requires a ridiculous amount of energy to make?
- Cesium and Strontium causing main health problems from leftover elements (graph in slides) of plutonium.
- Becquerel (in relation to radiation of wastage in the UK) is 1 disintegration per second.
- 09/11/22 10:02:23
- Assume actinide migration into the environment (because we’re operating long time scales), just looking at how to mitigate it.
- Plutonium can’t really be understood relative to the environment because it’s only been around really since the 40’s.
- 16/11/22 10:13:31
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Unlikely that Lanthanide’s enter I4 oxidation state, apart from maybe Cerrium.
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As you go across series of actinides oxidation state reducing. Because of the change in f orbitals and d orbitals. You expect lanthanide behaviour from late actinides.
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What to do with bad amount of Pu at 15cm depth
- Reducing environment, Pu won’t be oxidised. Soil and wind erosion through colloid spreading is the big issue at low depths.
- Higher oxidation states more soluble in water (more colloids). High to low pH.
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Look at defining oxidation states. Like the common form of ions.
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Notes
- The most common oxidation state for lanthanides is +3, but only for some of the actinides.
- Actinides are the elements from 89 to 103. They are all radioactive but Uranium and Thorium have particularly long half lives.
- All actinides are f block elements except final one.
- There are several ways that nuclear waste can be immobilized, including:
- Lanthanides in some cases can have +2 and +4 oxidation states.
- If actinides have other oxidation states, it’s normally higher than +3.
- The similarity in properties of the lanthanide series makes them hard to separate.
- The first four elements in the actinide series are naturally occurring.
- In transuranic elements which are also known as man made elements, the properties resemble those of lanthanides. The +3 oxidation state of transuranic elements are stable. They also show +2 oxidation state like lanthanides.
Encapsulation: Nuclear waste can be sealed in a container, such as a drum or a canister, and surrounded by a durable material, such as concrete or clay. This method is typically used for low-level waste with low levels of radioactivity.
Vitrification: Nuclear waste can be melted and converted into a glass-like material, which can be solidified and stored in a container. Vitrification is often used for intermediate-level waste with moderate levels of radioactivity.
Ceramification: Nuclear waste can be mixed with a ceramic material and formed into a solid block or pellet. Ceramification is often used for high-level waste with high levels of radioactivity.
PUREX, reprocessing of Pu and U
The extraction with tributyl phosphate (TBP) in the PUREX process (Plutonium and Uranium Recovery by Extraction) is based on the differences in the chemical properties of plutonium and uranium. TBP is a solvent that selectively extracts one of the elements based on its chemical properties.
In the PUREX process, the spent nuclear fuel is dissolved in an acid solution, such as nitric acid, to create a solution containing the plutonium and uranium. TBP is then added to the solution to extract the plutonium and uranium. The TBP forms a complex with the plutonium and uranium, binding to the metal ions and separating them from the acid solution.
The TBP is then stripped from the extracted plutonium and uranium, leaving a solution containing the other element. The solution is then passed through a second extraction and stripping cycle to separate the remaining element.