Question about this unusual galvanic bath

AI Thread Summary
The discussion revolves around the challenges of designing an electrochemical bath for separating metal alloys, specifically brass, using the cementation phenomenon. The process involves a zinc-copper alloy anode and a zinc cathode in a zinc sulfate solution, where copper ions are deposited onto zinc in a cementator. A key concern is preventing copper ions from bypassing the cementator and contaminating the cathode. The proposed solution of adding partitions to the bath to separate the anode and cathode raises issues of increased electrical resistance and power consumption, potentially leading to excessive heating. The focus is on finding a practical design that maintains effective circulation of the solution while minimizing resistance, ensuring optimal contact between the copper ions and zinc for maximum recovery. The effectiveness of the cementator is acknowledged as crucial, but the main challenge remains in the bath design to avoid direct ion transfer.
user_18041984
Messages
3
Reaction score
0
Hello dear forum members.
I've run into some problem and I'm hoping someone here can give me a hint on how to solve it.

There is an electrochemical method for separating some binary metal alloys based on the cementation phenomenon. I'll show you how it works with the example of separatting brass.

So, in figure A we have an anode made of zinc-copper alloy (1). The cathode (2) is made of zinc. The electrodes are in a solution of zinc sulfate, voltage is applied to them. The solution formed at the anode, containing copper ions and zinc ions, is pumped out by a pump into the cementator (3), which is a container filled with metallic zinc in the form of shavings or pieces. Since copper has a more electropositive potential, contact deposition of copper occurs in the cementator according to the reaction Cu2+ + Zn = Cu + Zn2+. The solution, freed from copper ions and containing only zinc ions, is fed into the cathode region, where only zinc is deposited on the cathode.

But, if the bath is assembled in this form, then the possibility is not ruled out that copper ions will enter the cathode region directly, bypassing the cementator. Then the cathodic zinc will be contaminated with copper.
Before me is the task of assembling such a bath in practice. In order to exclude direct contact of the anode solution with the cathode, I thought to introduce partitions (4) into the bath, as in Figure B. But then I realized that with these partitions, the electrical resistance of the bath and the power consumption will greatly increase. As a result, in order to provide the required current strength, I will have to apply a huge voltage and it will heat up, which is not good.

To be honest, I'm at a dead end. There are no partitions - there is mixing; there are partitions - there is resistance. Can anyone advise on the correct practical design of this bathtub?
IMG_20230813_214449.jpg
 
Chemistry news on Phys.org
Welcome to PF.

Your image is illegible. Please upload a better quality image. Thank you.
 
Here is what I could get without too much work:
_PF-user18041984.png
 
Hello Berkeman. I would still put this question in another section of the forum. The question is not about chemistry. The question is connected with the ratio of electrical resistance and the correct circulation of the liquid.
 
Your main problem is the effectiveness of the cementator. You want the solution containing Cu2+ to be in contact with the highest possible zinc surface and for the longest time, as these will maximize copper recovery. No changes to the galvanic chamber will change that.
 
Borek said:
Your main problem is the effectiveness of the cementator. You want the solution containing Cu2+ to be in contact with the highest possible zinc surface and for the longest time, as these will maximize copper recovery. No changes to the galvanic chamber will change that.
Thank you. This moment, of course, also matters. But for me there is no difficulty here - I understand that the cementator must have a large surface area, it must be long and so on. This is much easier for me to deal with. Now the question is how to properly make the bath itself in order to prevent the solution from getting from the anode to the cathode directly through this bath, bypassing the cementator.
So far, I see one option that I described above, but it will greatly raise the resistance of the system.
 
It seems like a simple enough question: what is the solubility of epsom salt in water at 20°C? A graph or table showing how it varies with temperature would be a bonus. But upon searching the internet I have been unable to determine this with confidence. Wikipedia gives the value of 113g/100ml. But other sources disagree and I can't find a definitive source for the information. I even asked chatgpt but it couldn't be sure either. I thought, naively, that this would be easy to look up without...
I was introduced to the Octet Rule recently and make me wonder, why does 8 valence electrons or a full p orbital always make an element inert? What is so special with a full p orbital? Like take Calcium for an example, its outer orbital is filled but its only the s orbital thats filled so its still reactive not so much as the Alkaline metals but still pretty reactive. Can someone explain it to me? Thanks!!
Back
Top