Patreon Preview - Lab notes on making potassium permanganate
Added 2023-09-08 03:31:28 +0000 UTCStill a work in progress, so let me know what you think. i'll probably add a few clips to flesh it out and reduce the "dead air time" at the beginning. I also need to write and insert the equations.
Feel free to ask any questions or request additions.
Comments
My source for Potassium Permanganate is "Pot Perm Plus". It's used to regenerate greensand filters for iron in well water. It's not cheap at ~$50 for 28 oz/800 grams, but I expect this container to last a lifetime, barring some new unforseen hyperfixation. :) I'd be willing to share from my stash if any other Patreon subscribers need some. With the caveat that I don't know if it would require Hazmat shipping, and if so how to do it. Still, thanks for the video. I enjoy watching it.
Elizabeth Greene
2023-09-12 17:45:42 +0000 UTCVery interesting! It seems temperature doesn't need to be too precise, just hot enough to get started. That's good to know. i'll keep using chlorine for improved yield, but it's good to know that carbon dioxide is very good as well. I'll be sure to mention its a safer alternative.
NurdRage
2023-09-08 13:37:19 +0000 UTCSo, your final yield is about what I routinely get. Starting for 25 g of 80% manganese dioxide, (i.e. 20 g of pure product), I collect about 8 to 9 g of KMnO₄. Knowing most of the manganese dioxide filtered out during the procedure is recyclable for further batches. I don’t use an oven. I use a blowtorch. The reaction is over in about 10 min, which is much quicker than the few hours you left the oven on. The blowtorch must be set to gently melt the initial mix of potassium hydroxide and potassium chlorate. Then as you add manganese dioxide in several steps, the temperature in increased and when all the manganese dioxide has been added, the blowtorch is set to full and blown over the thick paste until it reddens. The resulting mass, after cooling, is dissolved in water (it is already dark purplish at this point. If the mixture is green, then the yield is miserable, and that’s what you experienced in your first run → too much hydroxide remaining stabilises the manganate (pH ~ 14), whereas with less hydroxide, the manganate disproportionates immediately in water). I don’t bubble chlorine to oxidise the product, but carbon dioxide that I conveniently generate from a mixture of baking soda and citric acid in a RBF with water dripping from a funnel. More OTC and completely non-toxic. Ideally, the best way is to stop when the pH has reached around 10, in which case almost all (traces of) manganate has disproportionated back into manganese dioxide and permanganate. The solution is hot-filtered to eliminate manganese dioxide, evaporated (in my case down to ~ 150 ml), re-filtered hot and then left to cool down to ~ - 10°C to maximise the yield. The solution, being concentrated in ions, won’t freeze until it reaches ~ -10°C. [Follow-up] About manganese dioxide from batteries. I used that at first. It is contaminated with carbon. I’m not sure whether you can get rid of carbon by blowtorching the impure manganese dioxide, resulting in carbon turning into CO₂ and you’re left with pure MnO₂. It might work. I didn't try it. What is however certain, is that the carbon will burn in the crucible when heated with the potassium chlorate. The heat generated by the burning of the carbon soot is so high that the paste will turn red hot, and a sort of ‘hot wave' can be seen progressing from the point the potassium chlorate started to decompose to the antipodal point. If you load the crucible with a notable excess of potassium chlorate, I’m fairly certain you can burn away all the carbon and be left with pretty pure KCl. The problem being that, at the end, your yield is lower because you have to make for that additional KCl by increasing the amount of water you cool down, so that your final permanganate is not contaminated. Manganese dioxide from batteries is also difficult to process, because it is densely packed, and cannot really be turned up into powder unless it is thoroughly rinsed and crushed in water, because manganese dioxide from batteries is soaked in a brine of sodium hydroxide.
Mono Keras
2023-09-08 11:23:59 +0000 UTCI have recently been making my own KMnO4 from manganese dioxide, so I’ll watch this and let you know
Mono Keras
2023-09-08 09:08:19 +0000 UTCThis is very cool!
Michael Aichlmayr
2023-09-08 05:23:59 +0000 UTC
