Sciencemadness Discussion Board

Photoreduction of Uranyl Nitrate

Subcomputer - 29-9-2014 at 07:27

There's a possibility I'm getting over my head with this one, but here goes.

It's my understanding that one of the effects of UV light on the Uranyl ion is a reduction from Uranium (VI) to (IV). This has been previously used in photography, i.e. the "Uranotype" process.

Getting to my question, in the photographic processes, the Uranyl Nitrate was never "pure" - it was often mixed with other photosensitive metals that were reduced in the process, coated on paper with undescribed impurities, etc. What would happen in a large crystal of Uranyl Nitrate, with an adequate UV source, over a significant length of time?

careysub - 29-9-2014 at 09:58

Quote: Originally posted by Subcomputer  
There's a possibility I'm getting over my head with this one, but here goes.

It's my understanding that one of the effects of UV light on the Uranyl ion is a reduction from Uranium (VI) to (IV). This has been previously used in photography, i.e. the "Uranotype" process.

Getting to my question, in the photographic processes, the Uranyl Nitrate was never "pure" - it was often mixed with other photosensitive metals that were reduced in the process, coated on paper with undescribed impurities, etc. What would happen in a large crystal of Uranyl Nitrate, with an adequate UV source, over a significant length of time?


The uranyl nitrate crystal would fluoresce brightly, but I don't know if it would show a reaction the way silver nitrate crystals darken with sunlight exposure.

Behavior in solid crystal form is generally quite different from aqueous solution for most materials.

You might find it interesting to investigate the Westinghouse Lamp Division process developed and used during the Manhattan Project for photochemical reduction of uranyl nitrate to potassium uranous fluoride:
http://www.google.com/patents/US2690421
It was dropped from use after several months.

But what was old is (relatively) new, here is an Oak Ridge paper from the 1980s investigations UV uranyl niitrate reduction:

http://www.osti.gov/scitech/servlets/purl/10193761

[Edited on 29-9-2014 by careysub]

Subcomputer - 29-9-2014 at 13:28

Thank you, that does give me some help, particularly the discussion of reoxidation and scavengers in aqueous solution.

I was going to mention solution, but the concept of defining a "pure" solution got too complex in my mind what with molarity, possibility of oxygenation, discussion of excess nitrate, uranyl, etc. that it slipped my mind.

I just realized that this subforum being what it is, a crystal could indeed be special if I were to broaden the hypothetical from the assumed depleted stock to natural source or a more exciting isotope.

I think for now I'll look at reoxidation - maybe be able to figure out some experiments with it in solution, but the various papers such as the Westinghouse Lamp Division process that attempt to make functional use of this are very intriguing as a next step.