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Electrolysis project thread

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Electrolysis project thread

Unread postAuthor: saefroch » Sun Jan 02, 2011 11:46 am

I have no idea where this thread should go, but it seems to fit here since it's rather theoretical for now. One of the miscellaneous gifts I got for Christmas was an upgraded battery charger, so I have now retired my old cheapo one. Then I realized its output at the AA connection is 4 amps at 1.4V. Electrolysis anyone? :D

So 1.4V gets me pretty close to being able to use a NaCl solution without producing Cl2, if I can knock the potential down a bit. Is there any way to calculate the resistance of such a solution so I can get a voltage right between 1.36V and 1.25V? I've done some looking around on the interwebz but most of the information I can find on this is more technical than what I've learned. I could always just guess and check, but I've had some bad experiences with that...

I have an idea for an apparatus that I could use to collect the Hydrogen and Oxygen individually, so assuming I manage to do that, how could I calculate the equilibrium pressure?
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Unread postAuthor: Labtecpower » Sun Jan 02, 2011 12:46 pm

Why would you use a NaCl-solution?
NaCO3 is just as effective, and doesn't release Cl2-gas.
Also make sure you use some inert electrodes (Ti, MMO), otherwise they may corrode, bringing poisonous ions in your electrolyte.

I've read a little about electrolysis, as I want to produce sodium / potassium chlorate :roll:.
I will follow this topic, as it interests me.
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Unread postAuthor: BeaverRat » Sun Jan 02, 2011 1:03 pm

For the electrolyte, you want to either use NaOH or KOH... I built a massive drycell hydroxy gas system a year ago that peaked at output of 2.5LPM at 12 volts (2.1 ver plate gap) and roughly 50 amps. I believe it had 7 plate gaps (which is why I could use a 12 volt PSU). For the electrode, you want to use 316L Stainless Steel or pure Nickel.
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Unread postAuthor: saefroch » Sun Jan 02, 2011 1:52 pm

I'm pretty sure the carbonate ions in solution would decompose and contaminate the oxygen (which I may or may not use). If I can get the voltage low enough, I won't produce Cl2. If I cannot make NaCl work as an electrolyte, I'll try NaOH.

BeaverRat wrote:output of 2.5LPM at 12 volts (2.1 ver plate gap) and roughly 50 amps.
2.5LPM at what pressure? I am interested in how you came by a 50 amp power supply... Do you know what the potential across an individual gap was?

So far as electrodes are concerned, I must be horribly confused, because looking at an SRP chart, nickel breaks down at .25 volts. I've heard of Stainless Steel being used as an electrode, but I'd rather use graphite since it's so easy to come by.

I also have a (I should really find the other) random feed-through for a pacemaker that's pretty much a lump of Titanium with platinum wires fed through little rubies brazed in place with gold. Sound like a good electrode?

I'd rather not discuss chlorates here, though I too am interested in them :wink:.

EDIT: After doing some research, I think I have an equation to calculate the resistance of a solution, but this "K" is tripping me up. Image
Wikipedia wrote:K is an empirical constant
That's great... but I can't find anything else on it.
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Unread postAuthor: BeaverRat » Sun Jan 02, 2011 4:36 pm

First off, never use NaCl as an electrolyte... It will greatly accelerate the breakdown of the electrodes.

2.5 LPM at 1 ATM

PSU was a converted ATX computer power supply

I can't recall exactly what the potential was, but I think it was around 2.0 volts. Yes, the most efficient voltage is somewhere around 1.45 volts, but if you expect to make any decent amount of gas, use about 2 a 2.1 volts per plate gap.

Don't use graphite, been there done that... It falls apart and turns the solution black over time. Use either 316L SS or Nickel (which is much more expensive, but more efficient and more corrosion resistant)

The pacemaker wire stuff would work, but it's way to small unless .05 LPM is enough gas for you...

Go to YouTube and look at my profile BeaverRat01... I have some electrolysis bids there.
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Unread postAuthor: saefroch » Sun Jan 02, 2011 4:56 pm

Just trying to understand the physics behind what you're telling me here, don't think I'm arguing what you're stated.

Won't KOH or NaOH accelerate the breakdown of the electrodes for the same reason NaCl would?

Why would a higher voltage increase the rate of reaction? Wouldn't more current produce a greater rate of reaction, because of a larger charge flow?

I've heard of graphite being used in laboratory experiments, so I thought it might work for here. Maybe not. Wouldn't nickel break down or plate because of its low reduction/oxidation potential of .25V?
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Unread postAuthor: BeaverRat » Sun Jan 02, 2011 5:24 pm

Honestly, I don't understand the physics behind it all, but I was part of an electrolysis forum for a long time and NaCl was a big no no. The standard was always KOH or NaOH. I have used all three electrolytes, and I can tell you KOH is best with NaOH close behind. My first cell used NaCl and the plates desintigraded fast. My SS plates that were run in NaOH are good as new after being used heavily for a year.

V=IR, therefore as you increase voltage, amperage increases as well. Yes, amperage determines rate of reaction, but voltage is related to amps. You can also increase amperage by lowering the resistance of the water, you can do this up to a point by adding more electrolyte.

As for nickel, it is the best by far... I can't explain it because I don't know why. But from my own and other peoples tests, it is the most efficient and most corrosion resistant.

Also, don't exceed .25 amps per square inch of plate SA...

Read these, they will help

http://www.hhoforums.com/search.php?searchid=261345

Yes HHO is not a proper term, but it a generally accepted term for hydroxy gas.
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Unread postAuthor: saefroch » Sun Jan 02, 2011 5:42 pm

If you were running over 1.36V in a sealed cell with NaCl as an electrolyte, you were producing HCl, which would cause very fast degradation of electrodes. I don't mean to insult you or the electrolysis community, but NaCl should be perfectly fine if you can keep the voltage across the solution low. It seems you didn't if it was corroding the electrodes, probably mostly the cathode. KOH would work slightly better than NaOH, being a slightly stronger electrolyte.

What happens if one exceeds .25 amps/in^3 of stainless? Does this have something to do with hexavalent chromium?

Working with electrochemistry, you should be familiar with one of these, no? The data therein is why I'm confused about the use of a nickel electrode.

EDIT: Never mind my confusion over the nickel electrode, I think I got it. It doesn't react if the electrolyte isn't breaking down, and can be made to plate back onto the original electrode.

Tried the link, search returns nothing. HHO is a more common representation of water than you'd think. I've seen it many times before.
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Unread postAuthor: BeaverRat » Sun Jan 02, 2011 5:59 pm

That's the thing, you cannot make a decent amount of gas if you keep the voltage below 2 Volts per plate gap. The cell will simply not pull very many amps.

My suggestion is to use NaOH and run the cell at 2.05 volts per gap. At thy voltage, the cell will last many years.

About chromium, you must condition the cell first to extract the chromium from the plates. Don't pour the electrolyte down the drain after conditioning though, take it to a chemical waste center. Although you can run at .5 amps per square inch (I did) it will degrade the plates faster. It's been a while so I'm not sure of the relation of amps to hex chrome, but I think that all the hex is removed from properly conditioning. Increasing amperage over .5 amps (in most cells) will cause a uncontrollable rise in electrolyte temperature which will in turn increase amps exponentially (as temp increases resistance decreases) and overheat the cell.

If you use nickel plates, they are superior because you can run over 1 amp per square inch (less plates for the same amount of gas production). The .25 per inch only applies to SS plates. Heat in the cell is caused by electrical resistance in the plates, nickel has less resistance than SS.

EDIT: try this link, click on stats, and read my threads I started...

http://www.hhoforums.com/member.php?u=8942
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Unread postAuthor: saefroch » Sun Jan 02, 2011 6:47 pm

I'll look into extracting chromium, though it seems to me that defeats the point of using stainless steel, since it wouldn't be stainless anymore without the chromium...

Right now my power source is 1.4V, I do have others but I'd lose a vast amount of current. I could use 4"x4" plates and be right around .25amps/in^2. The cells in your setup are in parallel, right?

Honestly, I've at least doubled my knowledge of electrochemistry today from reading various articles, so I'll need time to digest.
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Unread postAuthor: BeaverRat » Sun Jan 02, 2011 6:56 pm

Be careful about the articles, some are scams and can be very misleading. All of the info in the link I posted is accurate though (as long as they were my posts/threads...

When conditioning, you only extract hex chrome from the surface of the plates.

Yes they are in parallel.

I sent you a YouTube message...
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Unread postAuthor: velocity3x » Sun Jan 02, 2011 7:37 pm

I designed and built this HHO generator a few years ago but, I parked it because I found HHO to be far to dangerous for my liking. At 12v 13a using 6oz limon juice concentrate and 1 gallon of distilled water, it produces 3 liters of HHO per minute with very low heating of the unit. The plates (12) have 557 in^2 total surface area, .050" plate separation and are +-+-+-+-+-+-

4" ABS case
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Unread postAuthor: BeaverRat » Sun Jan 02, 2011 7:59 pm

velocity3x wrote:I designed and built this HHO generator a few years ago but, I parked it because I found HHO to be far to dangerous for my liking. At 12v 13a using 6oz limon juice concentrate and 1 gallon of distilled water, it produces 3 liters of HHO per minute with very low heating of the unit. The plates (12) have 557 in^2 total surface area, .050" plate separation and are +-+-+-+-+-+-

4" ABS case


Hate to say it, but this isn't the best design, since you have no neutral plates, you have a plate voltage of 12 volts per gap (way too much)

Secondly, it is an open bath design, not a circulating sealed design so you have massive current leakage (electrons taking alternate route around plates)

Thirdly, those two factors combined make that a steam machine, you are probably producing 2.5 LPM of steam, and .5 LPM of hydroxy gas.

Fourth, it is physically impossible to produce 3 LPM of hydroxy gas using 156 watts. You have essentially created a perpetual energy machine because you claim to be making more energy in the form of hydrogen than you are puttin in.

I'm trying to not be rude, but I absolutely hate it when people post contraptions that are have physically impossible attributes...
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Unread postAuthor: saefroch » Sun Jan 02, 2011 8:02 pm

BeaverRat wrote:Be careful about the articles, some are scams and can be very misleading. All of the info in the link I posted is accurate though (as long as they were my posts/threads...
Not to be insulting, but I'm far more inclined to trust a published technical article like this than a web forum.

It's still rather confusing to me why one would want to remove the chromium from the plates at all, since only the chromium on the surface is making the steel "stainless." Having removed the chromium from the surface, it might as well not have been put into the alloy in the first place.

velocity3x wrote:limon juice concentrate
You used citric acid (a weak acid) for the electrolyte?

I would also like to just say that I do not plan on using the oxyhydrogen mix produced normally, but I plan to use the hydrogen and oxygen (if at all) separately.
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Unread postAuthor: metalmeltr » Sun Jan 02, 2011 8:10 pm

saefroch wrote:
velocity3x wrote:limon juice concentrate
You used citric acid (a weak acid) for the electrolyte?

Whats wrong with that? Acids serve as electrolytes in batteries all the time.
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