# Scrubbing methanol and ethanol from a gaseous mixture

I have a gaseous mixture (air) at a temperature of approximately 30 degrees Celsius in which the following gases are present:

• Oxygen 0 - 25%
• Carbon Dioxide 0 - 20%
• Methanol 0 - 100 ppm?
• Ethanol 0 - 100 ppm?
• Ethylene 0 - 20 ppm

I want to measure the concentration of each of the gases individually. That is not a problem with Oxygen and Carbon Dioxide but becomes a problem with methanol, ethanol and ethylene because of the cross sensitivity most sensors have for these gases.

Methanol and Ethanol are in liquid state at the temperature of 30 degrees Celsius. In the air the Ethanol and Methanol is present as vapor.

Would it be possible to design a 'scrubber' in which we bubble the air mixture through a container of for example liquid methanol to get rid of the methanol vapor and sequentially through a container of liquid ethanol to get rid of the ethanol vapor.

I can imagine that ethanol might also dissolve in the methanol liquid? And another issue would be the volatility of the ethanol and methanol liquid since we want to prevent new vapor getting into the air stream after the scrubbing.

Do you think this would be a feasible direction to investigate further? Another way to go would be to scrub it through water maybe? If we would be able to separate those two gasses we would then be able to determine all the concentrations individually by measuring the original air mixture and the scrubbed air mixture with two different sensors.

• A scrubber made by passing the gas through the liquids will probably increase their concentration in the gas. Jul 17 at 17:10
• Thanks for your reply. I was indeed wondering what the effect would be and thought it could go either way depending on the ratio between volatility and mass transfer. I am a bit rusty on this subject so thanks again for helping me out. Jul 18 at 6:12

If you are not concerned by the slight increase in $$\ce{CO2}$$ that this would create, and if there is sufficient oxygen, a hot mesh of copper, or better, of a platinum metal, would catalytically oxidize the three contaminants.