What is the possible cause of H2SO4 photoluminescence under UVA lamp (395 nm)? Is it SO2? Or is it something else (e.g. organics)?
I know that SO2 is measured by UV fluorescence, but I couldn't find confirmation, that it glows under this specific wavelength.
Here are some examples:
1. First batch of 96% H2SO4 (delivery)
2. Second batch from the same day (delivery; lesser glow)
3. A recovered and ready to be reused 96% H2SO4 (after denitration)
My initial guess was that it is indeed SO2, because after addition of few drops of H2O2 the fluorescence is gone. But due the fact that I'm making
piranha solution this way, the organic contamination cannot be ruled out.
Cheers. walruslover69 - 15-2-2024 at 13:02
I have synthesized fluorescent carbon nanoparticles by simply heating organic compounds in sulfuric acid 100-150C, they look quite similar. It could
be that that H2O2 is oxidizing them to CO2. Not definitive, but it is possible some decomposed organic material, is causing your fluorescence. palico - 15-2-2024 at 16:27
I think are just organic impurities.Bender84 - 17-2-2024 at 10:05
Thank you very much for the answers.
Believe it or not, but a few days earlier, I was preparing CQDs using the hydrothermal method with ascorbic acid and urea. When I first noticed that
the acid glows under UV light, I immediately thought of CQDs! It seemed absurd to me, though, so I focused on SO2.
It might be a silly question, but do you know if there are any guidelines regarding the quality of sulfuric acid in terms of its turbidity or
chemical content of organic matter if it is to be used in the nitration process? Also, which would be a better measure of the amount of organic
contaminants in the acid, COD (Chemical Oxygen Demand) or TOC (Total Organic Carbon)?SnailsAttack - 15-3-2024 at 16:27
I frequently see a similar ghostly-green fluorescence in many of my impure chemicals; alkaline battery electrolyte, oxalis clover extract, clamshell
calcium acetate, etc. It's most likely organic but I'm not really sure what it is.SnailsAttack - 15-3-2024 at 16:32
