Fully organic CO₂ absorbent obtained by a Schiff base reaction between branched poly(ethyleneimine) and glutaraldehyde

We used a water-in-oil emulsification method to prepare particulate CO₂ absorbents from branched poly(ethyleneimine) (PEI), utilizing ¹³C nuclear magnetic resonance spectroscopy to determine the amount of free PEI NH₂ groups and thus calculate the required cross-linker amount. The functional groups and reactivity of branched PEI particles were characterized by Fourier transform infrared spectroscopy, and their CO₂ absorption capacity was determined by thermogravimetric analysis. Dynamic light scattering measurements showed that the synthesized particles exhibited sizes of 0.2-2 μm and high surface areas, which resulted in high CO₂ absorption capacities of up to 2.18 mmol CO₂ per gram sorbent at 75 °C.