Gremwatch - 17-5-2017 at 14:43
I have been making some Ferrous Chloride in preparation to make some Ferrofluid and I noticed this odd black material forming in the reaction mixture
during the first batch. I have attached a picture of the filter paper I used to remove it from the mixture and I was wondering what you all might
think it might be. I originally thought it might be carbon from the steel but it almost appears crystalline.
Also during the second batch using the same iron source but after washing the iron and the jar the reaction is going in I noticed the black
substance precipitating on the upper surface of the jar instead of precipitating in the solution. I have attached a picture of this as well.
The iron source is misc nails and screws from an old tin can I found in my barn. And the HCL is from muriatic acid bought from a pool supply store.
The HCL was diluted with an equal volume of well water before adding the nails.
JJay - 17-5-2017 at 17:42
I have dissolved iron and steels in hydrochloric acid a few times. Usually, I do see some extremely fine black material that doesn't dissolve yet
passes through filter paper... I have always assumed it is carbon. When you dissolve large pieces of steel, it can cling to the surface as a thin
layer of black paste and slow corrosion unless scraped off or removed by stirring. I've had some luck removing it from mixtures by filtering through a
cotton ball, but if that doesn't work, you could use sand or diatomaceous earth.