Do I have colloidial gold?

[icejj]

Hello. I am wondering if this is colloidal gold, and need help identifying if it is colloidal gold or not. First, I got rid of base metals from gold filled material via dilute nitric. Then, I dissolved the gold foils from gold filled material in hcl and peroxide. After that, I dropped the gold with sodium metabisulfite and gave the solution some heat to speed up the drop. I was then left with this brownish colored solution. The solution was green before the drop. Any type of help would be greatly appreciated.

****post was edited for spelling errors***

 

[eaglekeeper]

Have you done a stannous test after you heated the solution.

 

[icejj]

Have you done a stannous test after you heated the solution.

Yes, the test was negative.

 

[Lino1406]

Hello. I am wondering if this is colloidal gold, and need help identifying if it is colloidal gold or not. First, I got rid of base metals from gold filled material via dilute nitric. Then, I dissolved the gold foils from gold filled material in hcl and peroxide. After that, I dropped the gold with sodium metabisulfite and gave the solution some heat to speed up the drop. I was then left with this brownish colored solution. The solution was green before the drop. Any type of help would be greatly appreciated.

****post was edited for spelling errors***

This conditions do not promote colloid production

 

[Yggdrasil]

Hello. I am wondering if this is colloidal gold, and need help identifying if it is colloidal gold or not. First, I got rid of base metals from gold filled material via dilute nitric. Then, I dissolved the gold foils from gold filled material in hcl and peroxide. After that, I dropped the gold with sodium metabisulfite and gave the solution some heat to speed up the drop. I was then left with this brownish colored solution. The solution was green before the drop. Any type of help would be greatly appreciated.

****post was edited for spelling errors***

What is the pH?

Edit to add:
It may be Iron from the filling.

 

[icejj]

The pH looks to be around 6.2-6.8. Maybe it's lower than 6.2 but I don't know if the strips that I have can test lower than that?

 

[Yggdrasil]

The pH looks to be around 6.2-6.8. Maybe it's lower than 6.2 but I don't know if the strips that I have can test lower than that?

That is strange, are you sure it is Peroxide and not Bleach that you have used?
Anyway the solution is best precipitated at about pH 2.
This brown color is also what I get if I use Copperas in stead of SMB.
How much Gold precipitated if any, how much did you expect and what do the Stannos say?

 

[icejj]

Yes it was peroxide that I used. Any idea on why the pH would be so high? I'll get some new pH strips to make sure Im getting an accurate reading. About 8.25 grams precipitated. I was expecting about twice as much to precipitate, but I knew that it could be considerably less due to the lack of markings on some of the material. Stannous text was negative.

 

[icejj]

This conditions do not promote colloid production

Do you know what would have needed to happen in this scenario in order to produce it?

 

[Lino1406]

Do you know what would have needed to happen in this scenario in order to produce it?

High shear, high speed stirring, surface active additive...

 

[nickton]

Why use smb before dissolving with aqua regia?

 

[nickton]

Okay. Sounds to me like you did things somewhat out of order, unless you just wanted to to use a lot more nitric than you had to.

First of all to remove gold from base metals you should use a bubbler in hcl, with a little bit of peroxide just to get the reaction started. When gold foils are removed and base metals for the most part dissolved, you then filter your AP solution (which is really I believe called Cupric chloride at this point). Next you put foils into clean hcl, after some rinses, and add small amounts of nitric acid until all gold is in solution. Then you filter again and drop your gold with smb.

You should not be adding hcl to nitric in order to make aqua regia. You should add nitric to hcl.

 

[nickton]

Also peroxide and hcl will not put gold into solution ( or "dissolve" go!d foils)

 

[Yggdrasil]

Also peroxide and hcl will not put gold into solution ( or "dissolve" go!d foils)

HCl and Peroxide is an excellent way of dissolving Gold, Pt and Pd.
But you need strong Peroxide, I use 20-30% ish and it do not work well for solid metal.

 

[icejj]

Okay. Sounds to me like you did things somewhat out of order, unless you just wanted to to use a lot more nitric than you had to.

First of all to remove gold from base metals you should use a bubbler in hcl, with a little bit of peroxide just to get the reaction started. When gold foils are removed and base metals for the most part dissolved, you then filter your AP solution (which is really I believe called Cupric chloride at this point). Next you put foils into clean hcl, after some rinses, and add small amounts of nitric acid until all gold is in solution. Then you filter again and drop your gold with smb.

You should not be adding hcl to nitric in order to make aqua regia. You should add nitric to hcl.

Out of order? How so? I believe that it is common practice to use dilute nitric on gold filled material, although HCL can be used with a bubbler as well (more cost effective than dilute nitric, although slower). Question: is HCL+bubbler faster than HCL+heat? I did want to start experimenting with using HCL to get rid of base metals, but I'd like to know what type of time frame I'd be working with when going that route if possible.

**Post was edited for terminology correction

 

[Yggdrasil]

Out of order? How so? I believe that it is common practice to use dilute nitric on gold filled material, although HCL can be used with a bubbler as well (more cost effective than dilute nitric, although slower). Question: is hcl+bubbler faster than hcl+heat? I did want to start experimenting with using hcl to get rid of base metals, but I'd like to know what type of time frame I'd be working with when going that route if possible.

It is HCl not hcl, in Chemistry these things matter.
Copper do not dissolve in HCl, but with an air bubbler, the dissolved Oxygen in the HCl oxidize the Copper and this is in turn is dissolved in HCl and creates Cupric Chloride which in turn Oxidize more Copper.
Dilute Nitric works well too, but for many the Nitric is too expensive and hard to get.

 

[markscomp]

is there any way that you could post the simple rules up front before someone joins --- like a super prerequisite to entry

and the reading of Hoke's and the waste disposal are mandatory - it may make things a little easier for all!

things may not be as monotonous as we feel it is...

 

[J.Najam]

is there any way that you could post the simple rules up front before someone joins --- like a super prerequisite to entry

and the reading of Hoke's and the waste disposal are mandatory - it may make things a little easier for all!

things may not be as monotonous as we feel it is...

I think @Yggdrasil always mentions it for any newbies that do come here

 

[Marcel]

Colloidal Iron can be produced from iron using peroxide. It's not limited to producing colloidal gold; it can also produce other colloidal metals. I had a similar experience, where I obtained the same color, but as far as I can remember, it had no significant quantity or value.
I remember having the same color after using too much peroxide and some traces of base metals (Iron, Copper, Nickel) left in the beaker.

Colloidal iron in a solution typically has a brownish color. This is because colloidal particles are in the nanometer size range, which results in a characteristic optical effect known as the Tyndall effect. When light passes through a colloidal suspension, it is scattered by the particles, causing the solution to appear turbid and brownish in color. (From chemistry book in my bookshelf)

 

[icejj]

Colloidal Iron can be produced from iron using peroxide. It's not limited to producing colloidal gold; it can also produce other colloidal metals. I had a similar experience, where I obtained the same color, but as far as I can remember, it had no significant quantity or value.
I remember having the same color after using too much peroxide and some traces of base metals (Iron, Copper, Nickel) left in the beaker.

Colloidal iron in a solution typically has a brownish color. This is because colloidal particles are in the nanometer size range, which results in a characteristic optical effect known as the Tyndall effect. When light passes through a colloidal suspension, it is scattered by the particles, causing the solution to appear turbid and brownish in color. (From chemistry book in my bookshelf)

Thank you. This was very helpful.