Electrolysis cell, experts!

[vodka]

Hello,

searching for experienced experts.

Keywords: lead dioxide anode, perchlorate, chlorate, power supply.

 

World wide web has been searched throw up and down, now I would like to discuss about it with practics.

 

I’ve done some, but I’m not satisfied with:

1. Lead dioxide connection

2. Power supply

[woelen]

Regarding the power supply issue, there already is a nice thread on this subject.

Have you visited Visser's pages on electrolysis already?

[vodka]

Regarding to the first link - are you really happy with 3amps? It yield a poor return, what a waste of time. At the moment I'm testing a car accumulator charger with regulator of 0-9V (3,7V 6A, about 300W was last experiment).

 

The other link - been, read and more. Now wondering about great cord connection to lead, any ideas?

[woelen]

Vodka, what you are stating is nonsense! 300W of power? Come on! 3.7V and 6A gives you just 22.2 Watts of power. Even with 9V and 6A you only have 54W of power. Besides that, try to use current control. On my site I explain why that gives more consistent results. Using 9V between the electrodes is far too much. It is not true that higher voltage gives better yields. A too high voltage allows more difficult (but unwanted) reactions to occur simultaneously, such as formation of O2 from water, instead of Cl2 from Cl(-) ions.

 

There is another issue. Even 3A is too much for me now. Using graphite anodes you should not exceed a current density of more than 100 mA/cm². With my (quite large) graphite rods, I cannot go much above 1A. Only by using parallel rods, I can increase the current.

 

And there is another thing. What do you mean with "what a waste of time". What does it matter? Patience is a great thing, especially in pyrotechnics. Patience learns you to think things over twice.

 

I have no experience with PbO2 electrodes. Too much toxic waste with that, I do not use them now and I do not intend to use them.

[vodka]

Hi again,

it was my testing experiment, I was using car lamps 12V, about 300W, but if voltage is 3,7V offcourse it does lower watts (what I missed to write)

"Waste of time" I meant it does take so much time to get some chlorate 1A=5gram per day?

 

I do not like graphite anodes cause their low conduction. So I am testing PbO2. But I don't have brilliant idea for connection to power. Titanium won't be corrosive, but its conductivity isn't good, SS - better but not perfect and its conductivity also, silver would be perfect, but its price.

 

Lead dioxide, ye, does have hazardous waste what should be treated safely, but if one anode makes quite many (20?) kilos of chlorate/perchlorate I think it is worth to make.

So has anyone here made PbO2 anodes?

[5614]

I was using car lamps 12V, about 300W

If those numbers are correct then you were using 25A. That is a lot! That is why woelen and myself somehow doubt it is 300W. Maybe it is capable of supplying a max of 300W, but I doubt your 12V car battery is supplying the full 25A it would need to to make it a 300W power supply.

[vodka]

5614 - it's an car accumulator charger that gives out 12V/24V and 30A

 

woelen - I don't want to rise voltage. my plan is rising amps. I've the regulator, but I've to change cords suitable for greater amps - fat copper cords (10mm2 would be ok).

 

 

Any ideas about PbO2?

[YT2095]

all that means is that it`s Capable of Delivering that much power, not that it`s actualy doing that!

it`ll give you your 300w on a dead short.

 

think of Mains electricity, cappable of powering many kilowatts of power to your heaters and oven etc... and yet if you put a 60watt bulb across the same line, you`ll only draw 60 watts and the bulb won`t explode.

 

a fixed resistance will only draw X amount of power, no matter what the supply may be capable of delivering.

[woelen]

A charger, that is capable of giving out 30A usually does not really give out that amount of current. If you switch on the device and attach a 100 Ohm resistor between its terminals, then you only have 120 mA of current. The actual current depends on the load.

 

Low conduction of graphite rods? I'm quite sure that the limiting of the current is not due to the carbon rods, but due to the resistivity of the electrolyte. If you really want to run 25A of current through your cell, then you'll need a large anode or a set of rods in parallel. I'm quite sure that in such a case, the conductivity of all rods in parallel is not an issue at all. The contact potential between rod and liquid and the (low) mobility of ions, compared to the mobility of electrons in the wires and rods is the limiting factor of the current. Using a 12V supply is not a good idea anyway. You need resistive network between the cell and the power supply. You really don't want 12V accross your cell.

 

So, if you have PbO2 electrodes, just wrap some copper wire on them/around them and cover the copper wires with some teflon tape carefully, in order to assure that the corrosive fumes from the cell do not reach the copper. This will be quite hard, but with careful taping and careful "glueing" (using silicone kit or something like that), you can make a construction which holds for a day or so. You need to watch your cell anyways on a regular basis. If you plan to run it with such high currents, then you'll also have to deal with all the heat produced. And yes, that will be a LOT.

 

Just use the idea's of Visser's site and stick to that. It is a proven method for making chlorate, albeit not the fastest way.

[vodka]

Accumulator charger (makes from 220V to 12V and AC to DC) is a power supply to voltage regulator.

I don’t use resistors, my schematic is based on IGBT transistor (1200V, 600A), it has 6 modules, I’m using 3 of them, because 12V, 30A power supply. IGBT doesn’t heat more than 10%. Choke (is it the correct word for inductor?) makes ultrasonic sound if volts are low (must be glued, when stops). IGBTs control panel allows regulate volts from 2,8V to 9V. The cell will never reach more volts than it is expected to produce chlorate approx 3,6V or perchlorate approx 5,5V. Ampere is depending on electrodes size. Voltage will be as it is set.

 

Then I started the topic, I wasn’t satisfied with power supply, but for now after testing, I am quite ok, I can regulate volts like I want, and amps are ok also.

 

PbO2 gets my full attetion now. Most of fireworks components are very toxic, but they don’t make us give up.