Please let me know what you discover with your FTIR analysis.

Sorry Dingus, I can't let you see the FTIR results. Sorry.

                  

Just kidding  ----->>>
Don't worry buddy, all the results will be posted here.

Hi Everyone,

I have some interesting data:

I did some FTIR scans of the grey blob I obtained from the zinc regeneration experiment that was suggested by Dr. Linnard Griffin. This grey blob formed on the aluminum electrode that replaced the zinc electrode in a cell that had run for a while. These results are interesting and confirmed a few things.

If you look at the bottom picture you will see the scan for the regenerated electrode after it had been dried for three hours at 250?F. This was needed because the IR picks up the -OH group of the water molecule as a large broad peak between about 2900-3700 (cm-1). These numbers are the wavenumbers at the bottom scale of the scan. So it is important to drive off any residual water from the sample in order to get a valid scan. Notice the bottom picture has really only one prominent peak around 1400-1500(cm-1). This made it very easy for the computer to do a library search and come up with the identity as Zinc Carbonate. (ZnCO₃).

This was confusing, and I was trying to understand where the carbonate ion came from. Afterall, there is no carbon in the cell. Just NaOH, Mg, Ag, Tungsten, and zinc electrodes in water. No carbon anywhere.

Then came the revelation. I had assumed earlier that zincate complexes:

 [Zn(OH)₄]^-2

were part of the make-up of the cell, and were the main form of the solublized Zinc. This was the form I expected to see on the IR. The zinc scan with a -OH peak after it had been dried; but if you look at the top scan and see the second and third scans you will see a gradual reduction of the OH peak as it dried. These are the air dry, 30 min dry, and 3 hour dry samples at 250?F.

What is really happening is that the Zinc hydroxide [Zn(OH)₂] in the blob

is reacting with Carbon Dioxide (CO₂) in the oven. This follows the formula:

Zn(OH)₂    +    CO₂   -->     ZnCO₃    +   H₂O
  Zinc           Carbon            Zinc          Water
Hydroxide      Dioxide          Carbonate

So the water is no longer seen because it is driven off, and the carbonate group is formed.

So the original statement I made earlier, that zincates make up the regenerated zinc, was correct.

Also the scan for NaOH has the same promenant peak as the Zinc Carbonate, but the group around 3500(cm-1) was missing, so I know the NaOH did not effect the scans.

What this all means is that I was correct. The solublized zinc in the cell that is regenerating is in the form of zincate complexes; and this is what makes up the regenerated zinc electrode. It also tells me that there is a possibility that doing the dip/dry method with the aluminum electrode may seal the aluminum enough, if done properly, from reacting with the NaOH solution and producing hydrogen.

So I will try to get a zinc coating on the aluminum electrode first. Hoping to completely seal it from the NaOH solution; and once that coating is composed of many dried coats, I will again immerse it in the solution and connect it to the tungsten and see if it regenerates, or is used up, or whatever else happens.

I think this is what Dr. Griffin wanted us to do.

Thank you for your interest.

Hi Dingus,

I am thinking of an angle here that I plan on experimenting with. Plating the aluminum with zinc may be difficult to do properly. I am thinking that as long as the aluminum is protected from the NaOH solution, that it won't be consumed so this is what I propose:

Take a zinc electrode, drill a small hole into it, and "force" an aluminum wire or electrode into the hole. Then lower the zinc/aluminum electrode into the reactor solution. This would be a protective coating of the entire zinc electrode over the aluminum. Then see what happens.

I have a feeling the zinc will replate on the zinc electrode without electrical power. Next, connect this to a tungsten electrode, but connect it on a zinc surface, not the aluminum one. This seems strange, but I am hoping by avoiding electrical contact with the aluminum electrode then the aluminum can encourage the replating of the zinc at the same time the zinc is being consumed without consuming the aluminum. I think you know what I mean.

I will try this out as soon as I get more aluminum electrodes. Probably tommorrow.

Dave

Hi Paul,

I'll consider this. Maybe a 250?F oven. Drill the hole in the zinc electrode just smaller than the aluminum electrode. Pop the zinc in the oven for a bit, then insert the aluminum electrode into the hot zinc and let it cool. Sounds good. I'll probably do it this way. Thanks.

Just a thought,  when I deal with issues like this I also try and take into consideration what metallurgical properties I am up against. Paul, not a bad idea to heat one up and then you can even cool the other part down, stick it in the freezer for awhile or use a fire extinguisher on it to cool it down. I  just wonder this. When you use two dissimilar metals, which one will expand first when it gets hot? If the part that you are making the hole in expands faster than the one part you are putting in the hole then you may have an issue.  If it is the other way then fine you are in good shape. What temperature will this system run at when it is all said and done?

For a test mode I am sure you would have no issues like Paul said, I am just trying to think ahead is all. The more things that are brought up now, the less things that will need to be covered later.

Regards

Trump

ResinRat2,

Sometimes simple things are the hardest to find, we always look at the hard way. your way is very good idea. Simple and gives you a chance to change it if you need to.

have a good night !

Regards


Trump

Hi Everyone,

I've got some interesting results

I took a zinc electrode and drilled a hole through its top, then threaded it. Next I took a thinner aluminum electrode and tapped a thread around its end. This I inserted into the zinc electrode. Next I took a fresh solution of the NaOH, Mg, Ag, and deionized water and inserted this electrode so only the zinc was immersed. I added a tungsten electrode to the cell. This is a normal control cell except that the zinc electrode has an aluminum electrode inserted in its top. Pictures are posted below.

Normally when I connect the zinc and tungsten electrodes in a normal control cell the tungsten begins to give off hydrogen gas.

In this cell there was no activity off the tungsten or zinc. No gas at all. This is odd in itself; but what is most interesting is that if I take the connection off the zinc surface and connect the tungsten electrode and aluminum portion of the zinc/aluminum electrode, then the tungsten immediately begins giving off gas at the normal rate.

What does this mean? I don't know right now. This is new ground and I am anxious to see what happens. I know that if I put an aluminum electrode in solution that has had the reaction going for a while, that zinc hydroxide will begin to replate on the aluminum electrode, and keep going until there is a huge blob.

In this case I am not sure but my hypothesis is that the zinc will replate as it is consumed by the reaction. I am probably wrong but I don't know for sure. We will see as the time progresses.

Thank you for your interest.