Electrolysis of Seawater under pressure

[jayron11]

I have perused a number of related posts, but have not found the answer I'm looking for.

My problem is this:

I need to electrolyze seawater and capture the gas at a given pressure (I'm mixing the O2 and H2).

It seems to me that there should be a relationship of the form:

dVolume (or dMoles) ~ Pressure, temperature, voltage, conductivity

Some have indicated that pressure has no effect on the electrolysis of water, but this makes no sense to me - at a minimum, the gas will return to solution in the water under pressure and not be useful.

Any information would be greatly appreciated. Thanks a lot...

 

[Bob S]

Sounds interesting. You should also measure the number of Coulombs (as well as Joule energy) per Mol of H2 to determine efficiency. It should be (I think) about 192,900 Coulombs per Mol H2 (~2 grams, 22.41 liters at STP), not including inefficiencies. This may be pressure and temperature dependent.
Bob S

 

[astrokreng]

I can provide some insight into the electrolysis of seawater under pressure. First, let's discuss the basic principle of electrolysis. Electrolysis is a process in which an electric current is passed through a solution, causing a chemical reaction to occur. In the case of seawater, the two main components, sodium chloride (NaCl) and water (H2O), are broken down into their respective ions, Na+ and Cl-, and hydrogen (H2) and oxygen (O2) gas.

Now, let's address the issue of pressure. It is true that pressure does not have a direct effect on the electrolysis reaction itself. The voltage and conductivity of the solution are the main factors that determine the rate of the reaction. However, pressure can affect the solubility of gases in the seawater, as you mentioned. This means that under high pressure, the gases produced during electrolysis may remain dissolved in the water instead of being collected as intended.

To overcome this issue, you can adjust the temperature and pressure of the system to maintain a balance between the production of gas and its solubility. This can be achieved by using a gas collection vessel with a controlled pressure release valve, or by adjusting the temperature and pressure of the solution during the electrolysis process.

In addition, it is important to consider the composition of the seawater itself. The concentration of salt and other dissolved minerals can affect the conductivity of the solution and therefore, the rate of the electrolysis reaction. It may be necessary to adjust the voltage and conductivity to achieve the desired rate of gas production.

In summary, while pressure may not have a direct effect on the electrolysis reaction, it can impact the solubility of gases in the seawater. To overcome this, careful control of temperature, pressure, and solution composition is necessary. I hope this information helps in your research.