Ur a lifesaver if u can help me

[deleted-358038]

In a microbial desalination cell, there is a cation exchange membrane connected between the desalination chamber and the cation chamber and an anion exchange membrane connected between the desalination chamber and the anode chamber. My question is that, where does the cathode chamber get H+ from to combine with the 02 to form water.

PS: I know that the o2 in the cathode chamber comes from the oxygen pump. I am just curious where does the H+ comes from since there is the microbial desalination cell has both anion exchange membrane and cation exchange membrane

[norman40]

Hello Jeffdunum,

There’s a Science Buddies project on microbial fuel cells that’s described at this link:

https://www.sciencebuddies.org/science- ... ml#summary

The background section of the project explains that the hydrogen ions (H+) are produced by bacterial digestion of organic matter. There are several links at the end of the background section that will have additional and useful information on microbial desalination cells.

I hope this helps. Please ask again if you have more questions.

A. Norman

[deleted-358038]

Hi, First of all, thanks for replying. I understand about the basic microbial fuel cell. The H+ is able to transfer from the anode to cathode due to the presence of salt bridge. However if u look at this picture

https://www.researchgate.net/figure/270 ... n-exchange

There is an Anion exchange membrane (CEM) between the desalination chamber and the anode chamber. This AEM prevents positive charge ions from passing through. Therefore, how is the H+ going to be transferred from the anode chamber to the cathode chamber?

[norman40]

Hi Jeffdunum,

Sorry that I misunderstood your question.

You are correct that the anion exchange membrane blocks passage of H+ from the anode chamber. Thus there is no transfer of H+ from the anode chamber to the cathode chamber. The source of H+ in the cathode chamber is dissociation (or ionization) of water.

Protons and electrons are produced in the anode chamber by bacterial oxidation of the biomaterial. The anion exchange membrane prevents protons passage out of the anode chamber. Anions from the saltwater chamber pass through the anion exchange membrane and into the anode chamber.

Electrons produced at the anode are conducted by a wire to the cathode. In the cathode chamber, oxygen is reduced with H+ to form water. As H+ is consumed by this reaction, cations from the saltwater chamber pass through the cation exchange membrane and into the cathode chamber.

A couple of interesting articles about the operation of microbial desalination cells are at the following links:

https://www.researchgate.net/publicatio ... tion_Cells

https://www.researchgate.net/publicatio ... case_study

I hope this helps. Please ask again if you have more questions.

A. Norman