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

Abstract

AbstractAlthough 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.