Production Techniques and Chemistry > Colloidal Gold Production

Colloidal Gold first try.

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tony14:
I'd bought purest salt/citrate/cinnamon I could find. 1mg Au ingot. Used brass as K and rod to hold clip for ingot.

Q: Presumably brass is ok for electrodes?

I used Kephra's method (but changed salt as I saw somewhere he had upped it) and Cassia cinnamon made to his method that I've been using for Colloidal Silver.

500ml DW
Salt: 240mg (actually 250mg - difficult to get right)
Citrate: 200mg (actually 260mg for same reason)
Cinnamon: 1.5ml (30 drops for me) - should have been 2ml - just a try.
Large K; 1mg Au ingot spaced to get 350mA at 31V (turned out @ 10mm - need more volts? - Add booster - Booster works off 12V & only $AUS17: Google: DC-DC 600W 10-60V to 12-80V Boost Converter Step-up Module car Power Supply)

Heated water in nukerator to @ 75C; onto hotplate; added Salt; citrate and stirbarred for 5mins then added 30d cinnamon (1.5ml) Colour changed cinnamon-like.

Waited for 85C, electrodes in. Current adjusted for 350mA and ingot had to be lowered to @ 60% immersed. (Bit worrying as plated-tin alligator-hold-clip almost in the bubbling around ingot - need more volts to lift ingot/move apart.)
Started Google-timer, stirbar running slow.

At @ 7mins 85C and quite red colour. Colour got deeper red and @ 15mins current started falling - 320mA @ 17mins - 300mA @ 19mins (now 95C) Stopped at 20mins. Colour clear and deep ruby-red - YAY!
(Seems current falling indicates salt-gone, it's done??)
Nuked it for 2mins - then - bugger! The stirbar!

Weighed ingot and it was still 1mg?? Must have bought a dodgy mini scale? Ingot definitely looked very clean below the water level mark, so I put a 56mg weight on the scale and the ingot had lost @ 26mg - non-linearity - or gravity in Oz?

Shared batch with wifey, tasted 'neutral,' maybe slightly cinnamon and when poured the colour was somewhat paler so maybe not long enough?

I think I stopped too soon as it's only 14mA-mins but the colour was so deep ruby red (cinnamon?) it was exciting & I didn't want any purple & current falling seemed important?

It's hard to show colour with my 'phone camera but would welcome any comments.

Thanks for all the methodology, seems I'm on my way and wifey can get off the multitude of tablets she's on!

tony

Shadsu:
You had more luck than me.
I had something red only in my third try. :)

kephra:

--- Quote from: tony14 ---I think I stopped too soon as it's only 14mA-mins but the colour was so deep ruby red (cinnamon?) it was exciting & I didn't want any purple & current falling seemed important?
--- End quote ---
ma-minutes does not apply to making gold.  The end point occurs when the solution runs out of chloride.

tony14:

--- Quote from: kephra on March 21, 2019, 01:08:04 PM ---
--- Quote from: tony14 ---I think I stopped too soon as it's only 14mA-mins but the colour was so deep ruby red (cinnamon?) it was exciting & I didn't want any purple & current falling seemed important?
--- End quote ---
ma-minutes does not apply to making gold.  The end point occurs when the solution runs out of chloride.

--- End quote ---

Thanks Kephra. I must be getting confused?
In your 20mA experiment you quote mA-mins (12V - 72ma-mins/ml; 40V - 42mA-mins/ml) and one post followed instructions achieving almost 42mA-mins/ml so my 14mA-mins/ml seemed weird as the resulting colour/clearness seemed too good?
Again, I used 500ml DW and I saw advice of 'double water quantity=double time' and I only ran for the 20mins advised for 250ml yet the result was good? This makes me even more confused.

What 'chloride'? Presumably this is sodium chloride that gets used-up and conductivity decreases reducing the formation of gold chloride, so, does the current falling indicate the end of the reaction and can be used as an 'end-point'?

tony

kephra:

--- Quote ---In your 20mA experiment you quote mA-mins (12V - 72ma-mins/ml; 40V - 42mA-mins/ml) and one post followed instructions achieving almost 42mA-mins/ml so my 14mA-mins/ml seemed weird as the resulting colour/clearness seemed too good?
--- End quote ---
I think you are thinking of someone else. I have always said ma-minutes is useless as an indicator because gold requires 3 electrons to be made into gold chloride and dissolve, and there is no guarantee that the same gold atom will collect all three. 

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