Bismuth compounds have many different uses in things like cosmetics, pigments and pharmaceuticals.
The most notable use of bismuth in pharmaceuticals is its use in Pepto-Bismol.
In Pepto-Bismol, it appears as a compound known as bismuth subsalicylate.
Each pill actually contains quite a lot of this molecule
and in this video we're gonna pull out the bismuth metal from it.
For the extraction of bismuth from Pepto-Bismol pills, all that's needed are the pills themselves, muriatic acid
also known as hydrochloric acid, and aluminium foil.
I used 120 pills of Pepto-Bismol,
about 260 ml of 31.45% hydrochloric acid,
and about 5 grams of aluminium foil.
The pills from the five bottles were emptied into a mortar.
Then, using a pestle, they were crushed up into as fine powder as possible.
It was kind of difficult but in the end I was left with a decent powder.
To a suitable container was added 1300ml of distilled water.
This was followed by the addition of 260ml of 31.45% hydrochloric acid.
Because foaming in this experiment can be an issue,
I opted to transfer it to a larger 4 litre Erlenmeyer Flask.
With strong stirring, the bismuth powder is added.
You'll notice that when the bismuth powder is added, the pink colour quickly disappears.
Depending on the dye that's used in the pills to make them pink,
the solution might turn white like mine did, or it might stay a pink color.
After all the bismuth powder had been added, a decent amount of foaming occurred
but since I had such a large Erlenmeyer flask, this wasn't an issue.
In this reaction, we're reacting the active ingredient of Pepto-Bismol which is
bismuth subsalicylate with hydrochloric acid to produce bismuth chloride and salicylic acid.
Salicylic acid is a side product in this reaction and since it's not very soluble in water,
it precipitates out and we'll need to filter it off.
I kept it stirring for 30 minutes to make sure that all of the bismuth subsalicylate had reacted.
The mixture is then filtered through a coffee filter using a funnel.
So now we have a solution that contains a decent amount of bismuth chloride
and we're ready to convert it to bismuth metal using aluminium.
The solution that comes through is still white and a little cloudy but that's okay.
The moment that the aluminium is added, black bismuth metal will start to precipitate out.
The aluminum reacts with the bismuth chloride to form aluminum chloride and the bismuth metal.
The solution is also still quite acidic due to the HCl so that will also react with the aluminum.
The aluminium was slowly consumed and more aluminium was added until the reaction was complete.
To test if the reaction is complete, a small drop of the solution can be wiped on a piece of foil.
If a clear solution produces a black precipitate, then there's still bismuth chloride in solution.
If it stays clear as shown here, then the reaction is complete.
If there is still bismuth chloride in the solution, it might look something like this.
When the reaction was complete, the large pieces of aluminum that remained were removed.
The mixture is then stirred and allowed to stand for about 30 minutes to allow for the HCl to react with any remaining aluminum.
The bismuth is then filtered off using a coffee filter.
I found a coffee filter actually worked best and anything with a finer grade took way too long to filter.
Once it was filtered, it was washed with water to remove any water soluble salts
and then it was washed with methanol to remove any salicylic acid that remained.
Then instead of waiting for it to dry, I wrapped it up in the filter paper and
squeezed all the water out of it and squish the bismuth into a hard ball.
The still wet ball of bismuth metal was transferred to a metal crucible and then heated using a torch to drive off the water.
Once it had cooled, the ball was crushed into smaller fragments.
You'll see here that some of the bismuth has turned yellow.
This is because when the bismuth was heated only slightly, it became bismuth oxide.
The bismuth powder and the fragments have a very high surface area
and heating them only slightly allows them to quickly react with oxygen in the air.
To prevent the oxidation, the bismuth metal must be melted under an inert atmosphere.
Using an inert atmosphere isn't the easiest for the average person so I found a way around this.
When heated up slightly, the bismuth reacts with the oxygen to form bismuth oxide
but when heated extremely hot, the bismuth oxide will break down to reform bismuth metal and the oxygen.
So you can see here when I heat the metal to red-hot, the bismuth will start to liquefy.
Be aware that this does release toxic vapors and it isn't exactly the most efficient method.
Here I knock down the exposure so you can more easily see the red hot globs of bismuth metal.
Once everything that was going to liquefy liquefied, the bismuth metal was poured out.
After cooling, this is what the final bismuth looked like.
This was about 5 grams of bismuth metal which represents an extremely low yield of bismuth.
The yield was a very bad 22% but even if it were 100% it still wouldn't be a great way to get bismuth metal.
The best way would be to simply buy it online.
For the same price that I paid for the pills, I could easily get over 200 grams of nearly pure bismuth metal from somewhere like eBay.
Alternatively, you can dry the bismuth in an oven, crush it up and obtain the black bismuth powder.
It's best to heat it up in something that will transfer the heat well
otherwise it won't be able to get hot enough in order to break down the bismuth oxide.
My torch just was not hot enough to decompose the bismuth oxide in the crucible.
And instead of melting, it's simply all oxidized and never melted.
Also, the bismuth oxide can be easily turned back into the black bismuth powder by pretty much repeating the experiment.
So it can be dissolved in dilute hydrochloric acid to make the bismuth chloride like before
and then reprecipitated by reacting it with aluminum metal.