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servo
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[*] posted on 16-12-2021 at 21:30
A general Electrolysis Question!!!


Hey Everyone!!!

Well yesterday I started my first ever electrolysis project in my 13 years of practical chemistry and since I am a self learned amateur chemist I do have a lot of practical knowledge but lack the theory so I have been a frequent visitor of this heaven for any chemist. Now getting to the point

I would like to know how can I speed up or increase production in an electrolytic cell, do I need to increase voltage? size of electrodes or both?? or is there something else to consider

Any help is appreciated , thanks in advance
Take care everyone
Servo
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DraconicAcid
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[*] posted on 16-12-2021 at 21:52


To increase production, you want to increase amperage. You can do this by increasing voltage, or by decreasing resistance (which, I believe, would include surface area of the electrodes or increasing ion concentration).



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servo
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[*] posted on 16-12-2021 at 23:24


Quote: Originally posted by DraconicAcid  
To increase production, you want to increase amperage. You can do this by increasing voltage, or by decreasing resistance (which, I believe, would include surface area of the electrodes or increasing ion concentration).


Thanks a lot, so u mean both by increasing current flow or by increase contact surface area of electrodes with electrolyte will increase production??

I was just worried that if I increased current flow I might damage my final product ... But I do know that increasing current flow will also increase corrosion of electrodes..

Really appreciate the help ....
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B(a)P
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[*] posted on 17-12-2021 at 00:30


Increasing current flow increases the rate of reaction as you are supplying more electrons for the electrolysis reaction. To increase the current you need to turn up the current on your power supply or get a bigger power supply capable of a greater current output. To accommodate the increased current you may also need more surface area on your electrodes to prevent damage as electrodes will have a maximum current rating per unit surface area.

Edit - an increase in current will not damage your product unless the product is heat sensitive, as additional current will increase the temperature of your solution. This can be dealt with by placing your reaction vessel in a cooling bath.

[Edited on 17-12-2021 by B(a)P]
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[*] posted on 17-12-2021 at 02:21


In order for a reaction to occur you need a voltage that's equal to the activation energy of the reaction plus the over voltage needed to run a current (following ohms law). The reaction rate will be proportional to the current. To increase the current you can either increase the voltage (more energy lost as heat) or decrease bath resistance. This can be done either by increasing the electrode area, reducing the electrode distance or by increasing the conductivity of the electrolyte.



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servo
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[*] posted on 17-12-2021 at 08:05


Quote: Originally posted by Fulmen  
increasing the conductivity of the electrolyte.


If the solution is already saturated how can one increase the conductivity of electrolyte ??

And thanks for all the help everyone
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[*] posted on 17-12-2021 at 08:47


here be some electrosynthesis tips I got.

Increase the amps by reducing distance between anode and cathode does increasing current density.
If you want Insane amps run them at 0.5cm apart and the surface area of your electrodes matter as well as the type of electrolyte.
for instance 200cm^2 total surface area electrode at for instance 300ma/cm^2 will allow for 60 amps of current.
current density is the measure of current per given surface area of an electrode and is an important factor when talking about things like electrosynthesis.
Temperature of the electrolyte also directly affects current flow greatly as it increases ion mobility and thus running a cell at 80C will allow for much more current to flow.
Infact controlling the current as the temp rises would require the voltage to be reduced to maintain the current.
Constant current power supplies do this built in but for high currents like 60 amps your best bet would be to get a CHUX PSU.
This guy doesnt have as much precision as one of those lab bench PSUs but can go from zero to 5 volts for the 5 volt model and 0 to whatever volt for the other models.
The higher its max voltage the lower the current.
If you wanna control temp you must also know the amount of watts flowing into the cell as water bath cooling may be needed especially at higher amps.

Edit:
whoops forgot to talk about overpotential where basically any electrolysis reaction has a voltage at which the electrolytic reaction would occur and also the construction of the cell and the anode/cathode material of your choice affects this too.
This precision on choosing an operating doesnt matter unless you are doing organic electrochem but a general rule for inorganic electrochem is that you wont need anything higher than 5 volts unless you run membrane electrolysis.

[Edited on 17-12-2021 by mysteriusbhoice]
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[*] posted on 17-12-2021 at 14:20


Quote: Originally posted by servo  
Quote: Originally posted by Fulmen  
increasing the conductivity of the electrolyte.


If the solution is already saturated how can one increase the conductivity of electrolyte ??

And thanks for all the help everyone


I'm not aware of any way to necessarily increase the conductivity of your electrode, but you can certainly decrease its resistance by increasing its surface area. They are essentially the bottleneck of current flow in this case, so anything you can do to decrease that bottleneck, and thus increase current flow from electrode to solution will increase the rate of the reaction. The more electrode in contact with solution, the more current can transfer.

A wire is a resistor, so you'll want to minimize that resistance to your electrodes from your source as much as possible, too, as resistance is going to lead to loss in the form of heat. The key factors include:
length of your wire
diameter of your wire (ie gauge)
conductor composition (ie copper).

Given the fact that this process involves the use of a constant source of a decent amount of current, I would recommend using the largest practical diameter wire with the shortest practical length (although as diameter increases, resistance decreases, and thus you can afford some length). There's no harm in using a larger diameter/gauge than necessary, while there is significant risk in using a wire diameter/gauge size that is too small. You can google for ampacity charts to find the rating of different wire gauges. I'd recommend going a few gauges above the minimal rating to ensure safety.


As for voltage, you'll have to find the sweet spot for your system where enough current is flowing to allow for the reaction to go on at a good rate, but not so high that losses and damage occur.

Essentially, reduce resistance wherever you can and find the current capacity sweet spot for your system (and that your source can safely output, of course). Much of this can be calculated to dial in your system pretty well with fairly simple calculations you can find on google.
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[*] posted on 18-12-2021 at 01:13


Quote: Originally posted by servo  
If the solution is already saturated how can one increase the conductivity of electrolyte ?


I guess you can't. Just out of curiosity, what is the electrolyte? And what is your goal? "Electrolysis" is a bit vague...




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[*] posted on 18-12-2021 at 07:33


One thing that I haven't seen mentioned yet is that if you increase the current ("amperage") by increasing the voltage, additional heat will be produced in the cell (due to the ohmic resistance of the electrolyte itself). So, unless the heat is desirable, it is better to first try placing the electrodes closer together. This will reduce the resistance of the cell, and increase the current (at the same voltage) and will actually reduce heat production.



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[*] posted on 18-12-2021 at 12:00


Quote: Originally posted by Fulmen  
Quote: Originally posted by servo  
If the solution is already saturated how can one increase the conductivity of electrolyte ?


I guess you can't. Just out of curiosity, what is the electrolyte? And what is your goal? "Electrolysis" is a bit vague...


Switch to a more soluble electrolyte?




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[*] posted on 20-12-2021 at 00:44


Quote: Originally posted by servo  
Hey Everyone!!!

Well yesterday I started my first ever electrolysis project in my 13 years of practical chemistry and since I am a self learned amateur chemist I do have a lot of practical knowledge but lack the theory so I have been a frequent visitor of this heaven for any chemist. Now getting to the point

I would like to know how can I speed up or increase production in an electrolytic cell, do I need to increase voltage? size of electrodes or both?? or is there something else to consider

Any help is appreciated , thanks in advance
Take care everyone
Servo


Depends on what your goal is and what kind of reaction you are running in the cell. The general principle is that increased current shall result in increased reaction(s) rates(s). The abovementioned options to achieve this apply, but you have to consider that every option taken also tends to provoke side effects which could be detrimental to your setup or yield.....overheating, depletion of electrolyte near electrodes, overpolarisaion of electrodes, unwanted sidereactions, increased losses due to evaporation, damage to anodic side of the cell etc.

[Edited on 20-12-2021 by markx]




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[*] posted on 20-12-2021 at 02:35


The best thing about this forum is you rarely get a one liner answer, there is so much knowledge and I really can't find words to express my gratitude

for now I am concentrating on potassium chlorate so potassium Chloride is my electrolyte , what I have read so far is that 5 volts is voltage but this produces very small amount so I wanted to know how can I increase production

I do plan to do more electrolysis later but for now potassium chlorate is my main concern

once again I am very grateful to everyone and yes If anyone has more to offer I am willing to read , I like to read a lot actually
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[*] posted on 20-12-2021 at 03:28


There are a large number of posts on SM about this topic, make sure you check them out. A really great explanation/demonstration can also be found here chlorate
It would help to know your intended anode to answer your question on increased production. The answer is likely increase your anode surface area and the current supplied to the cell.
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[*] posted on 20-12-2021 at 14:54


chlorate cells also work better at around 75C.
so getting it to the right temperature is important.
if you are using MMO or graphite electrodes, adding dichromate can help.
Adding Calcium chloride to balance pH can also help but you will have to recrystallize the product.
Finally maintaining a lower pH is helpful. This can be accomplished by adding HCl.
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[*] posted on 22-12-2021 at 01:04


Quote: Originally posted by servo  


for now I am concentrating on potassium chlorate so potassium Chloride is my electrolyte , what I have read so far is that 5 volts is voltage but this produces very small amount so I wanted to know how can I increase production


'

5V is plenty enough for chlorate electrosynthesis. Your hindrance apparently lies in the configuration of your setup. Passive resistances created by too thin wires, small contact areas between coupling points in the circuit, too small electrodes in the cell too far apart, too weak of a power supply in terms of sourcing current etc.
With electrosynthesis the driving force is current not voltage: the more amperes you push through the cell, the faster your production rate. A minimal voltage to stand over the potential required to drive a certain reaction system+ losses is the goal with respect to voltage required. It seems to be quite instinctive that to increase current, one just turns up the voltage and all is well, but with cells that may often lead to trouble.
I would suggest to go over your setup step by step in order to minimize the resistance of your circuitry ( beefier leads, proper clean contact points, larger electrodes close to each other). Once you have done everything you can for getting rid of resistance in the circuitry, it comes time to play with applied voltage. If there are no obvious bottlenecks in the setup then a marginal change in applied voltage (on the order of 0.xV ) shall sharply manifest itself in a rather large change in the current flowing through the cell.




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