Determination of absorption efficiencies of carbon dioxide absorbents by gas chromatography

An HP-5880A gas chromatograph equipped with FID has been used to determine the efficiency of various CO(2) absorbents and some molecular sieves. Temperature, the CO(2) concentration in the absorbed gas mixture and space velocity of the gas mixture have effects on the absorption efficiency to different degrees, but temperature is a controlling factor. It has been established that in gas analysis the systematic errors arising from CO(2) impurities in the carrier gas are negligible when CO(2) is absorbed by carbon dioxide absorbents. Three methods for eliminating blank error are presented. The differential volume method through preconcentrating at the same time but at different flow-rates (DVMST) is proposed as the best method in preconcentration analysis. With the preconcentration technique, the minimum detectable level for CO(2) in a 10-litre sample is around 0.3 ppb(v/v).