Liquid membranes of amine liquids with glycol compounds were used for the separation of CO2 from atmospheric air. Because the CO2 concentration in atmospheric air is only 400 ppm, CO2 separation based on a facilitated transport mechanism by an amine compound has an advantage. The 3-layered construction consists of a thin liquid membrane of uniform thickness. Using a flat membrane module containing the amine/glycol liquid membrane, CO2 in the air was enriched in the sweep air that passed through the permeate side of the membrane module. The membrane durability, amine concentration and molecular structures of the amine components were investigated in terms of the CO2 concentration ratio in the sweep air. The present process for CO2 obtaining from air will be used for the forced culture of vegetables or strawberries in greenhouses. (C) 2011 Elsevier B.V. All rights reserved.