Sciencemadness Discussion Board

Potential Extraction of Useful or Noteworthy Compounds from Fluorescent Light Phosphor

SaccharinSlayer751 - 1-4-2019 at 17:05

I have recently acquired several kilos worth of crushed fluorescent lamp tube glass coated with whatever mix of chemicals they use in the white phosphor. I've done a bit of research on what could potentially be in this phosphor but couldn't find much information. It seems likely that there are some rare earth metals in there that might be interesting to extract but I'm not sure if they are in significant enough amounts. Just looking for any info that anyone has regarding what this stuff is made of and whether or not it would be reasonable to try to isolate anything from it. If so I'll plan on starting a seperate thread documenting that process if it succeeds. All I'm looking for is something akin to a list of potential ingredients with rough percent compositions. Thanks! :D

Sulaiman - 1-4-2019 at 17:23

Dr.Bob - 2-4-2019 at 09:23

Older lamps used to contain berylium compounds, which were quite toxic, so be careful if these are older ones. The phosphors vary by brand, type and size, but most are inorganic salts with some rare earth metal salts, and some other ones. I would wash the solids off of the glass first with plain water to get most of the rare earths as a slurry. You can filter or decant the soluble portion and test it for what percentage of the weight it contains, it might be very low, as the phosphors are mostly insoluble in plain water. Then I would check the solids for their elemental composition to se if they are worth anything.

SaccharinSlayer751 - 2-4-2019 at 17:49

Luckily the lamps I'm working with are quite modern so the only big risks are small amounts of mercury vapor and fine dust. Just today I crushed the glass bits some more and ran them through a strainer to get ~800g of white phosphor mixed with some small glass shards. Everything is really insoluble in water and forms a super stubborn colloidal suspension that takes ages to even partially settle :mad:, so I'm trying to avoid water washing and filtration/evaporation. I think my best bet now is to wash with some HCl to dissolve everything I really want and then possibly precipitate out the calcium impurity with some sulfuric acid. The only question is, are rare earth sulfates soluble enough?

CharlieA - 3-4-2019 at 16:14

I am just curious (I know, it killed the cat) as to why you are doing this. That is, do you have specific compounds/elements that you hope to extract? Do you have any way to analyze the phosphors for what compounds/elements may be present? (Here I wish I could help you, but I don't have a mass spectrometer...darn it!) At any rate, I look forward to your attempts and what you discover. Good luck. Charlie

Felab - 3-4-2019 at 23:07

This video might help you:

CharlieA - 4-4-2019 at 16:09

Thanks for the link. Interesting video , by an SM member. Now I've subscribed to his channel. I hope you'll post your experiences, if you try this.

SaccharinSlayer - 7-4-2019 at 16:10

Felab, that video was exactly the kind of thing I was looking for. My goal is going to achieve the highest separation possible between rare earth metal salts, and this provided some really great insight.