Gold Diffusion in Salts
This previous post contrasted how gold could be separated by pressure in deionized water, but not by diffusion (w199). I checked up on that diffusion sample again after 6 days, and while the retentate had mostly evaporated, there was no gold within the remaining filtrate.
As you may recall, there has been some discrepency with gold diffusion studies. All my results so far seem to agree that gold cannot diffuse through in DI H2O, however there is disagreement about whether it can diffuse through in 10 mM KCl. Since w199 seemed like a good membrane for separations, I snuck one last sample to test whether or not I could replicate the separations in KCl.
After one day, there was no obvious diffusion through the membrane. After two days however, the filtrate seemed like it had evaporated a bit. I still managed to remove a bit of it and test the absorbance using the Tecan. Here are the results:
As you can see, it appears that gold made it through into the day 2 filtrate. The day 2 retentate also seems like the gold has decreased in concentration, and perhaps there’s a bit of a right hand shift toward aggregation (which can happen to gold in 10 mM KCl over long periods of time). The membrane still appears to be intact, so I added some more buffer to the bottom and will check this sample again tomorrow.