separating carbon dioxide from biogas

[CaptainPanic]

I should probably have mentioned this earlier.

The pH will neccesarilly depend on the relative concentrations of ethanolamine and its protonated form and also on the carbonate/ bicarbonate ratio.

Adding CO2 will protonate the base (and form bicarbonate) and so the pH really will change.

I agree. CO2 in water will become carbonic acid (it's an equilibrium). That gives a hint that the CO2 will affect the pH. The carbonic acid can also form carbonates. Again, it's an equilibrium reaction. Because the solubility of CO2 is a function of temperature and pressure, this equilibium as a whole is a function of temperature and pressure.

 

What I meant in my earlier post is that in order to absorb the CO2 cheaply, and also desorb it cheaply, you don't want to add any other chemicals. So, it is desirable if you (as an owner of a CO2 aborption factory) don't have to change the pH by constantly adding acids and bases to absorb and desorb the CO2 or something.

[ashraf]

Dear , Is there any chemical which can activate bacterial action on digester( Contains mixture of Water and manure) and also enhance the production of Biogas from same input.

Further more, is there any use of sodium bicarbonate which is the product of biogas purification by passing it through Caustic soda solution.

How can i know that Caustic solution is no more to remove further gas so i can recharge the solution of NaOH.

I shall be much grateful.

The whole reason for the concentrated NaOH solution is that it provides more NaOH in a smaller amount of liquid. This way you don't have to change out the solution as often. Also, the higher the concentration, the greater the frequency with which the CO2 molecules will interact with the OH- ions in solution to give you the HCO3- ions that should be produced. In fact, I think on the space shuttles they use honeycombs made of KOH to absorb the CO2 that the astronauts are breathing out.

[John Cuthber]

"Dear , Is there any chemical which can activate bacterial action on digester( Contains mixture of Water and manure) and also enhance the production of Biogas from same input."

 

None that I know of, but it's possible. Check the literature.

 

 

"Further more, is there any use of sodium bicarbonate which is the product of biogas purification by passing it through Caustic soda solution."

Sodium bicarbonate is a marketable material, but not a very profitable one. Also you would need to ensure quite high purity before you could sell it.

Probably the best thing to do would be to boil the solution of sodium bicarbonate to make a solution of sodium carbonate which will absorb CO2 as long as it's cold and under pressure.

 

"How can i know that Caustic solution is no more to remove further gas so i can recharge the solution of NaOH."

The easiest way would be to measure if CO2 is getting through it.

But none of this really makes sense. It's easier to not bother. The CO2 won't stop the gas being used as a fuel in most processes.

[Suxamethonium]

There is probably more of a market here for the bio-chemists. Genetically engineering the bacteria involved so as to produce only a certain range of compounds and sequester unwanted products using some abstract way (some chemical version of photosynthesis comes to mind). This is all hypothetical of coarse, but it's probably the more likely route of investigation- why waste energy treating a product if there is the potential to tweak the system manufacturing the product?

[ashraf]

Dear Jdurg,

U r great, i am succeeded in purifying biogass from CO2 and water vapours , furthermore i have also get rid of H2S by placing iron filling in the way of biogas during purification process.

I have a problem yet,

How could i identify that NaOH solution needs recharge,

Please tell some remedy like physical appearence of solution, Ph of solution or any simple way,

Thankful to u.

The whole reason for the concentrated NaOH solution is that it provides more NaOH in a smaller amount of liquid. This way you don't have to change out the solution as often. Also, the higher the concentration, the greater the frequency with which the CO2 molecules will interact with the OH- ions in solution to give you the HCO3- ions that should be produced. In fact, I think on the space shuttles they use honeycombs made of KOH to absorb the CO2 that the astronauts are breathing out.

[henchaka]

what if i pass the biogas through a solution of sodium chloride and water, can it be able to extract CO2 and H2S as well as the moisture

[danielchas]

dear collegues, I am a farmer producing tomatoes in green house, so this discussion is veryy interesting, because if we can separate the co2 from the rest, we can reuse as fertilizer in form of gas, (and that means 30% more yield if the rest of the conditions are right), and the metane gas for engine energy.

so you manage to find a cheap solution, we can produce food high tech in remote areas with biogas, solar and conventional energy.

co2 is a valuable gas for us in green house production, metane and niox NO.

co2 we need day time with light