We prepared Zinc tellurite glasses samples with Gold (AuCl) nano-particle by using Platinum crucible.......Now there is gold nano-particle inside the crucible that can not be cleaned by using HF.....What can we do to clean it????
Dear kasim,
Gold will dissolve in aqua regia. But then aqua regia can attack platinum also.
It all depends how deep your gold nano particles are embedded, or hog strongly they are adhering to platinum.
Normally Gold can also be cleaned with nitric acid. this is the best information I have to share with you.
I have one question let say, after the cleaning how will we ensure that the platinum crucible is complete cleaned off with Gold.
Is there any test that can be performed to detected any residual gold nano particles still left in the crucible.
K. Sreenivas
Dear Mr. Rawanduzy, maybe you can use a complexing agent as cyanide (see https://en.wikipedia.org/wiki/Gold_cyanidation). But, platinum can also be solubilized (http://stacks.cdc.gov/view/cdc/10086/cdc_10086_DS1.pdf). However, due to higher contact surface of gold nanoparticles, the kinetic of dissolution to gold is major than to platinum. Maybe works. Cyanide is very toxic, therefore you cannot discard to environment. You can destroy cyanide with sodium hypochloride at pH 10 (adjust using sodium hydroxide). For each 1 gram of cyanide you will need 60 a 70 ml of sodium hypochloride at 2%. I hope to have helped. Good lucky.
Thanks a lot for your valuable answers...but what about heating the crucible to 1200C in a furnace??? I mean.... heating it with a special chemical composition that can be use it as a sweep-out material to clean the crucible from the nano gold?
You may consider to clean the platinum crucible from gold nano-particles with a warm to hot (40─70 ºC) solution of potassium iodide (40 g) and iodine (20 g) in 100 ml of water for about 10 minutes. Potassium or sodium cyanide aqueous solutions could alternatively be used, but there is a considerable safety risk involved with the manipulation of these solutions. It is not advisable to heat the crucible with a flux to melt the gold nano-particles at high temperatures due to the considerable risk of Pt-Au alloying.
Also about platinum cleaning ― but addressing a possible sulphate contamination: https://www.researchgate.net/post/How_to_clean_the_platinum_Wilhelmy_plate_from_salt_deposits
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