Crosslinked polyethyleneimine-based structures in different morphologies as promising CO2 adsorption systems: A comprehensive study

Abstract

Although there are many studies on CO2 adsorption via PEI-modified carbon particles, metal–organic frameworks, zeolitic imidazolate frameworks, and silica-based porous structures, only a limited number of studies on solely cross-linked PEI-based structures. Here, the CO2 adsorption capacities of PEI-based microgels and cryogels were investigated. The effects of various parameters influencing the CO2 adsorption capacity of PEI-based structures, for example, crosslinker types, PEI types (branched [bPEI] or linear [lPEI]), adsorbent types (microgel or cryogel), chemical-modification including their complexes were examined. NaOH-treated glycerol diglycidyl ether (GDE) crosslinked lPEI microgels exhibited higher CO2 adsorption capacity among other microgels with 0.094 ± 0.006 mmol CO2/g at 900 mm Hg, 25°C with 2- and 7.5-fold increase upon pentaethylenehexamine (PEHA) modification and Ba(II) metal ion complexing, respectively. The CO2 adsorption capacity of bPEI and lPEI-based cryogels were compared and found that lPEI-GDE cryogels had higher adsorption capacity than bPEI-GDE cryogels with 0.188 ± 0.01 mmol CO2/g at 900 mm Hg and 25°C. The reuse studies revealed that NaOH-treated GDE crosslinked bPEI and lPEI microgels and cryogels showed promising potential, for example, after 10-times repeated use >50% CO2 adsorption capacity was retained. The results affirmed that PEI-based microgels and cryogels are encouraging materials for CO2 capture and reuse applications. © 2024 The Author(s). Journal of Applied Polymer Science published by Wiley Periodicals LLC.