Modeling CO2-facilitated transport across a diethanolamine liquid membrane

We compared experimental and model data for the facilitated transport of CO₂ from a CO₂–air mixture across an aqueous solution of diethanolamine (DEA) via a hollow fiber, contained liquid membrane (HFCLM) permeator. A two-step carbamate formation model was devised to analyze the data instead of the one-step mechanism used by previous investigators. The effects of DEA concentration, liquid membrane thickness and feed CO₂ concentration were also studied. With a 20% (wt) DEA liquid membrane and feed of 15% CO₂ in CO₂–air mixture at atmosphere pressure, the permeance reached 1.51E−8 mol/m² s Pa with a CO₂/N₂ selectivity of 115. Model predictions compared well with the experimental results at CO₂ concentrations of industrial importance. Short-term stability of the HFCLM permeator performance was examined. The system was stable during 5-days of testing.