4 ms·

Suddenly a new element on the table piqued my interest. Selenium [0]. Seems relatively abundant, already used in glass and semiconductor making, but a tad toxic

Suddenly a new element on the table piqued my interest. Selenium [0]. Seems relatively abundant, already used in glass and semiconductor making, but a tad toxic like arsenic etc. Any chemists weigh-in on Se ? [0] https://en.wikipedia.org/wiki/Selenium https://en.wikipedia.org/wiki/Selenium

pomian 3y ago
Selenium is a fascinating element. Very necessary for healthy life, UpTo to a level, then it may be toxic. Different areas of the planet have more present in the soil. So on some places, it is added as a supplement to feed(especially animals - horses cows), but if that feed is given to an animal that doesn't need the supplement, it may kill it. (See polo pony kerfuffle.) There are various states of selenium which makes analysis, and chemistry complex. Se^-2,0,+2,+4, and even +6. Similar(but not) to sulphur and in strange ways to iron. Certain oxidation states are more reactive(obviously) and therefore are more toxic. But when dealing with environmental issues, finding which state of selenium is present, is extremely difficult, and requires very complex laboratory procedures. Total selenium does not answer most questions. Chemistry can be fun!
gilleain 3y ago
A couple of biochemical points about selenium: * Selenocysteine <https://en.wikipedia.org/wiki/Selenocysteine https://en.wikipedia.org/wiki/Selenocysteine> is the 21st amino acid - essentially cysteine with selenium instead of sulfur. * Selenoenzymes are used in humans for peroxide metabolism and in the thyroid
pfdietz 3y ago
Selenium is actually not very abundant. It's the 69th most abundant element in the Earth's continental crust, at an average concentration of about 50 ppb. It's less abundant than silver and only 10x more abundant than platinum. https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth...
- nonrandomstring 3y ago
  > less abundant than silver Hmmm. So are these proposed batteries viable? Are they mostly Sulphur and a bit of Selenium (and presumably some other stuff)?
  - pfdietz 3y ago
    Here's the USGS 2023 Mineral Commodities Summary for Selenium. https://pubs.usgs.gov/periodicals/mcs2023/mcs2023-selenium.pdf https://pubs.usgs.gov/periodicals/mcs2023/mcs2023-selenium.p... World production for 2022: 3,200 tonnes World reserves: 81,000 tonnes There's not a whole lot available. It occurs at 0.5 to 12 ppm in coal, so large amounts of coal ash might be a future resource. It's not economic to extract that now, vs. current secondary extraction from copper anode slimes.
    - pfdietz 3y ago
      I will add that the concentration of Se in carbonaceous chondrites is around 20 ppm. Eventually we might mine asteroids for it.
ajb 3y ago
(Not a chemist) Yeah selenium is fun, it's used in photocopiers - the drum which the image is copied over is made of it. The drum is charged, then the light projected onto it caused the selenium to conduct, allowing the charge on those areas to leak away. Then toner particles are allowed to stick to the charged areas, and printed on to paper. Well, that's how they used to work. They are all multi function now so use a CCD scanner and printer combination.

pomian 3y ago

Selenium is a fascinating element. Very necessary for healthy life, UpTo to a level, then it may be toxic. Different areas of the planet have more present in the soil. So on some places, it is added as a supplement to feed(especially animals - horses cows), but if that feed is given to an animal that doesn't need the supplement, it may kill it. (See polo pony kerfuffle.) There are various states of selenium which makes analysis, and chemistry complex. Se^-2,0,+2,+4, and even +6. Similar(but not) to sulphur and in strange ways to iron. Certain oxidation states are more reactive(obviously) and therefore are more toxic. But when dealing with environmental issues, finding which state of selenium is present, is extremely difficult, and requires very complex laboratory procedures. Total selenium does not answer most questions. Chemistry can be fun!

gilleain 3y ago

A couple of biochemical points about selenium: * Selenocysteine <https://en.wikipedia.org/wiki/Selenocysteine https://en.wikipedia.org/wiki/Selenocysteine> is the 21st amino acid - essentially cysteine with selenium instead of sulfur. * Selenoenzymes are used in humans for peroxide metabolism and in the thyroid

pfdietz 3y ago

Selenium is actually not very abundant. It's the 69th most abundant element in the Earth's continental crust, at an average concentration of about 50 ppb. It's less abundant than silver and only 10x more abundant than platinum. https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust https://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth...

nonrandomstring 3y ago
> less abundant than silver Hmmm. So are these proposed batteries viable? Are they mostly Sulphur and a bit of Selenium (and presumably some other stuff)?
- pfdietz 3y ago
  Here's the USGS 2023 Mineral Commodities Summary for Selenium. https://pubs.usgs.gov/periodicals/mcs2023/mcs2023-selenium.pdf https://pubs.usgs.gov/periodicals/mcs2023/mcs2023-selenium.p... World production for 2022: 3,200 tonnes World reserves: 81,000 tonnes There's not a whole lot available. It occurs at 0.5 to 12 ppm in coal, so large amounts of coal ash might be a future resource. It's not economic to extract that now, vs. current secondary extraction from copper anode slimes.
  - pfdietz 3y ago
    I will add that the concentration of Se in carbonaceous chondrites is around 20 ppm. Eventually we might mine asteroids for it.

ajb 3y ago

(Not a chemist) Yeah selenium is fun, it's used in photocopiers - the drum which the image is copied over is made of it. The drum is charged, then the light projected onto it caused the selenium to conduct, allowing the charge on those areas to leak away. Then toner particles are allowed to stick to the charged areas, and printed on to paper. Well, that's how they used to work. They are all multi function now so use a CCD scanner and printer combination.