Hi
as I am currently in the state of exploring new possibilities to refine various feeds, I started to think about implementation of ascorbic acid to my general refining procedures - as it is somewhat different reducing agent than metals/SO2 or formic acid.
I have some experience with ascorbic acid Pd precipitations from nitrate solutions, but this was in my beginnings, and I didn´t measured things like pH or ammounts precisely... So not much meaningful memories
From what I read in various articles issuing ascorbic acid reduction, there is written that Pd will drop even from acidic solutions, like 0,5M HNO3 (one article about nuclear waste treatment). Does this stand, or it is just another BS "wow" article ?
My intention will also be to apply it to the chloride media palladium feeds. But there I found not too much info regarding any favourable conditions, pH control or anything in general. From my theoretical sight/background, coordination of Pd into tetrachloro complex anion will result in lowering it´s oxidation potential - thus making it harder to reduce.
Why I want to explore more routes:
Many times, I work with awfully contamined feeds containing up to 10 elements inside. pH adjustment is very difficult, since a lot of various compounds drastically lower the solubility and they precipitate as various hydroxides, or even compounds upon slight pH rise, and are very difficult to filter/retain values in the filter cake viciously.
So classic formate reduction is great pain to do, as you need to firstly adjust pH to say 2, then filter that formed goo (which took ages), then add formic, adjust pH second time... And pray no more junk will come out
On the other side, I want to slowly minimize DMG use - as I know there are better practices, tho beating the selectivity and simplicity of DMG would be very hard.
I also considered something like formaldehyde, as it has very low molar weight and it is also fairly strong reducing agent. But also, not much information regarding formaldehyde as reducer also. Cheap tho
Ascorbic acid is attractive possibility - even knowing the fact that it will drag copper (Cu2O/Cu) to the precipitate (this is still possible to wash out with ammonia/peroxide). Unlike hydrazine, non-toxic, easily accessible, OTC...
So I want to firstly ask here, if anyone done palladium with ascorbic acid and is willing to share his experiences on some specifications about conditions, pH management, temperature of the drop - maybe favourable conditions how to not reduce copper to metal, but only Cu2O etc... I searched the forum before and only found some hints.
Thanks for the responses
orvi
as I am currently in the state of exploring new possibilities to refine various feeds, I started to think about implementation of ascorbic acid to my general refining procedures - as it is somewhat different reducing agent than metals/SO2 or formic acid.
I have some experience with ascorbic acid Pd precipitations from nitrate solutions, but this was in my beginnings, and I didn´t measured things like pH or ammounts precisely... So not much meaningful memories
From what I read in various articles issuing ascorbic acid reduction, there is written that Pd will drop even from acidic solutions, like 0,5M HNO3 (one article about nuclear waste treatment). Does this stand, or it is just another BS "wow" article ?
My intention will also be to apply it to the chloride media palladium feeds. But there I found not too much info regarding any favourable conditions, pH control or anything in general. From my theoretical sight/background, coordination of Pd into tetrachloro complex anion will result in lowering it´s oxidation potential - thus making it harder to reduce.
Why I want to explore more routes:
Many times, I work with awfully contamined feeds containing up to 10 elements inside. pH adjustment is very difficult, since a lot of various compounds drastically lower the solubility and they precipitate as various hydroxides, or even compounds upon slight pH rise, and are very difficult to filter/retain values in the filter cake viciously.
So classic formate reduction is great pain to do, as you need to firstly adjust pH to say 2, then filter that formed goo (which took ages), then add formic, adjust pH second time... And pray no more junk will come out
On the other side, I want to slowly minimize DMG use - as I know there are better practices, tho beating the selectivity and simplicity of DMG would be very hard.
I also considered something like formaldehyde, as it has very low molar weight and it is also fairly strong reducing agent. But also, not much information regarding formaldehyde as reducer also. Cheap tho
Ascorbic acid is attractive possibility - even knowing the fact that it will drag copper (Cu2O/Cu) to the precipitate (this is still possible to wash out with ammonia/peroxide). Unlike hydrazine, non-toxic, easily accessible, OTC...
So I want to firstly ask here, if anyone done palladium with ascorbic acid and is willing to share his experiences on some specifications about conditions, pH management, temperature of the drop - maybe favourable conditions how to not reduce copper to metal, but only Cu2O etc... I searched the forum before and only found some hints.
Thanks for the responses
orvi