The Use of Zeolite Molecular Sieves for Trapping Low Concentrations of CO2 from Environmental Atmospheres

Abstract

We describe a simple method for trapping low concentrations of CO₂ present in gas mixtures, such as air and soil respiration, using a zeolite molecular sieve (type 13x) for environmental carbon isotope studies. We employ reusable molecular-sieve cartridges and a lightweight battery-driven pumping system, developed to enable CO₂ collection in difficult and dangerous terrain or under extreme climatic conditions. The results of a small field experiment suggest that CO₂ could be quantitatively trapped on and recovered from the 13x molecular sieve, without any fractionation of the stable carbon isotope. The δ¹³C of CO₂ was also independent of the amount of air ≤18 liters and rate at which it was collected, i.e. ≤ 1 liter of air/min.