CO2 capture through membrane gas absorption with aqueous solution of inorganic salts-amino acid salts

K3PO4, K2HPO4, and KH2PO4 as activating agents were added into the aqueous solution of amino acid salts glycine (GLY) to form activated absorbents (AAb) for CO2 capture. The performances of GLY and AAb for CO2 capture were evaluated using a membrane contactor-regeneration cycled setup. The effects of activating agent concentration and flow rate on overall voluminal mass transfer coefficient, mass transfer flux, and capture efficiency were studied. The phosphates exhibited remarkable activating effects on CO2 capture in the membrane contactor; the activation extents of the phosphates were in the order of PO43− > HPO42− > H2PO4−. A small amount of activating agent is sufficient to promote the CO2 capture. The changes of hydrodynamics in the membrane contactor can improve mass transfer performance and enhance mass transfer flux to a certain extent; the essential factor for enhancing the mass transfer efficiency in membrane gas absorption is the performance of absorbents used.