Carbon Dioxide removal from biogas

[AidanWare]

I am currently carrying out batch testing on several different solid organic wastes with regards to their potential methane yield using anaerobic digestion under mesophillic conditions. I want to remove the carbon dioxide from the gas that is being produced so that the sole methane fraction of the biogas can be measured directly (the batch testing is preliminary testing therefor don't need to remove any of the other gases contained in the biogas produced). The gas produced is being measured using a liquid displacement system and I hope to pass the gas through a chemical solution to remove the carbon dioxide before displacing the liquid to measure the volume of methane produced.

 

I am wondering if anyone has successfully done this at laboratory scale using chemical absorption and if so what chemical is best suited to this application. I have been looking into using sodium hydroxide or else calcium hydroxide but cannot find a definitive answer as too what chemical is best suited and at what concentrations they should be used etc.....Any help or alternative suggestions would be greatly appreciated.

[Wilmot McCutchen]

NaOH is being used for air capture of CO2: http://www.nytimes.com/2013/01/06/business/pilot-plant-in-the-works-for-carbon-dioxide-cleansing.html?nl=todaysheadlines&emc=edit_th_20130106&_r=0

 

The difference in molecular weight between CO2 and methane (16 vs. 44 g/mol) would make centrifugal separation possible, as in this apparatus:

http://www.freepatentsonline.com/7901485.pdf

[John Cuthber]

Have you seen this

http://en.wikipedia.org/wiki/Carbon_dioxide_scrubber

In any event, the limiting factor might be how much the hydroxide costs and what does it cost to get rid of the carbonate/ bicarbonate produced.