Dropping nano-gold from solution the EASY way!

[Alondro]

So, proof of concept result here! I was watching Sreetips older vid of him testing if hot sulfuric acid could dissolve gold at all, and watched as it merely TRANSIENTLY dissolved a smidgen of gold, only to redeposit it almost instantaneously on larger gold particles present, until much of the powder eventually merged into a couple large blobs.

I realized this could be a simple way to recover nanogold, which often forms when dropping gold from a dilute solution with metabisulfite. Since adding SMB causes the formation of sulfuric acid, and in a properly denoxed solution, there should remain a mix of HCl and sulfuric acid, I hypothesized that a similar effect could occur if this nanogold suspension with gold powder at the bottom of the beaker was gently simmered.

So, I had a tiny gold drop to perform, and deliberately added only about 80% of the SMB I calculated would be required, dropping most of the gold. Then I added the rest of the SMB a day later, and formed the reddish nanogold suspension (after allowing it to settle overnight again).

Then, I gently simmered it for about 2 hours. EUREKA!!! The solution became cloudier and cloudier as it simmered, then suddenly began to clear up and became very pale blue-green once cooled! All the nanogold had collected onto the gold powder and settled out! The gold powder particles have also become much larger, and made it VASTLY easier to wash as an additional bonus, since it settled out swiftly when disturbed (in only seconds!) and didn't float upon the surface tension.

Here are two pics taken just after the simmering. The solution went from the color of strong black tea (reddish-brown) to this pale color, which became totally clear once it had cooled and all the powder settled.

 

[Martijn]

i was told that the smaller gold will be cleaned from oxides and can clump togehter better when simmering in hot solution with a dash of H2SO4. but you think it's dissolving and growing back to larger pieces? Anyway, the result is the same. The theory you propose is quit interesting.

 

[BGDOCK]

I’m so lazy I just put it in the gold stock pot full of iron sulfate , HCl , sulfamic acid, etc and let it settle out in a week .

 

[orvi]

So, proof of concept result here! I was watching Sreetips older vid of him testing if hot sulfuric acid could dissolve gold at all, and watched as it merely TRANSIENTLY dissolved a smidgen of gold, only to redeposit it almost instantaneously on larger gold particles present, until much of the powder eventually merged into a couple large blobs.

I realized this could be a simple way to recover nanogold, which often forms when dropping gold from a dilute solution with metabisulfite. Since adding SMB causes the formation of sulfuric acid, and in a properly denoxed solution, there should remain a mix of HCl and sulfuric acid, I hypothesized that a similar effect could occur if this nanogold suspension with gold powder at the bottom of the beaker was gently simmered.

So, I had a tiny gold drop to perform, and deliberately added only about 80% of the SMB I calculated would be required, dropping most of the gold. Then I added the rest of the SMB a day later, and formed the reddish nanogold suspension (after allowing it to settle overnight again).

Then, I gently simmered it for about 2 hours. EUREKA!!! The solution became cloudier and cloudier as it simmered, then suddenly began to clear up and became very pale blue-green once cooled! All the nanogold had collected onto the gold powder and settled out! The gold powder particles have also become much larger, and made it VASTLY easier to wash as an additional bonus, since it settled out swiftly when disturbed (in only seconds!) and didn't float upon the surface tension.

Here are two pics taken just after the simmering. The solution went from the color of strong black tea (reddish-brown) to this pale color, which became totally clear once it had cooled and all the powder settled.

I personally doubt that it will redissolve and reprecipitate, however addition of acid changes surface charges of particles - enabling agglomeration.

Gold in acid is known to clump, and most of the precipitates tend to clump on simmering - this is somewhat general, but not certain.

Procedure you proposed work in most occasions, however we should generally beware of the situation when you produce the particles somewhere "in the middle" between nice microgold and fine nanogold. If you form these (usually black or at least transition between black/brown) on the spot by adding SMB/SO2/sulfite all in once and in excess, you will form relatively uniform particles - and from my personal experience this "fraction" of size is only clumped in hot acid with great difficulty (if it even is).

However, thumbs up for bringing this up Nicely written and performed. We need more basic "research" work to be done by members. Converting ideas into at least experiments

 

[Dreamer]

Interesting. Lately I've been boiling my precipitate gold after dropping with SMB and stannous negative to kill off the Sulfur Dioxide just because I can't stand the smell. After it cools the odor is barely noticable and the solution is nearly clear. Clean-up has been much easier as the sediment falls rapidly on each step. Your theory fits with my experience. Thank you Alondro.

 

[Alondro]

Interesting. Lately I've been boiling my precipitate gold after dropping with SMB and stannous negative to kill off the Sulfur Dioxide just because I can't stand the smell. After it cools the odor is barely noticable and the solution is nearly clear. Clean-up has been much easier as the sediment falls rapidly on each step. Your theory fits with my experience. Thank you Alondro.

Yeah, whether the particles are simply clumping, or the gold dissolves briefly and redeposits instantly from the unstable sulfate formed, the result is that it makes the gold powder much easier to handle!

 

[Amol Gupta]

So, proof of concept result here! I was watching Sreetips older vid of him testing if hot sulfuric acid could dissolve gold at all, and watched as it merely TRANSIENTLY dissolved a smidgen of gold, only to redeposit it almost instantaneously on larger gold particles present, until much of the powder eventually merged into a couple large blobs.

I realized this could be a simple way to recover nanogold, which often forms when dropping gold from a dilute solution with metabisulfite. Since adding SMB causes the formation of sulfuric acid, and in a properly denoxed solution, there should remain a mix of HCl and sulfuric acid, I hypothesized that a similar effect could occur if this nanogold suspension with gold powder at the bottom of the beaker was gently simmered.

So, I had a tiny gold drop to perform, and deliberately added only about 80% of the SMB I calculated would be required, dropping most of the gold. Then I added the rest of the SMB a day later, and formed the reddish nanogold suspension (after allowing it to settle overnight again).

Then, I gently simmered it for about 2 hours. EUREKA!!! The solution became cloudier and cloudier as it simmered, then suddenly began to clear up and became very pale blue-green once cooled! All the nanogold had collected onto the gold powder and settled out! The gold powder particles have also become much larger, and made it VASTLY easier to wash as an additional bonus, since it settled out swiftly when disturbed (in only seconds!) and didn't float upon the surface tension.

Here are two pics taken just after the simmering. The solution went from the color of strong black tea (reddish-brown) to this pale color, which became totally clear once it had cooled and all the powder settled.

Could you please provide a link to the video.