Reactive CO2 absorption mechanism of a soybean-based (SBB) solvent containing 18 amino acid salts in polyvinylidene fluoride (PVDF) hollow fiber membrane-based gas-liquid membrane contactor

The CO2 absorption mechanism of a soybean-based (SBB) solvent comprising 18 different amino acid salts was investigated via a polyvinylidene fluoride (PVDF) membrane-based gas-liquid membrane contactor. The CO2 absorption behavior of the SBB solvent was investigated by using different Nuclear Magnetic Resonance (NMR) techniques and the method of Statistical Design of Experiment (DoE). The results revealed that the presence of K-arginate showed the most significant effect on CO2 absorption flux in the SBB solvent. K-aspartate and K-glutamate were not CO2-reactive and the presence of them reduced the CO2 absorption flux. The SBB solvent reacted with CO2 to form carbamate at low CO2 loading, and then partial carbamate was hydrolyzed to bicarbonate at high CO2 loading. The CO2 absorption behavior of the SBB solvent was mainly determined by the nature of the components mixing. The interactions among different amino acid salts and the associated SBB solvent degradation were not found in the CO2 absorption process. The presence of hydrophobic amino acid salts in the SBB solvent inhibited the CO2 absorption activities in the membrane contactor process.