Design of an Intelligent Nanofiber-Based Solid Amine Adsorbent with High CO2 Capture Capacity and an Ultralow Regeneration Temperature

Solid amine adsorbents cannot typically maintain desirable CO2 capture capacity while having ultralow regeneration temperatures. To address this issue, a novel thermoresponsive nanofiber-based solid amine adsorbent (TRCNF/PEIA) with high amino density and high content of thermoresponsive intelligent groups was designed and prepared using epichlorohydrin to rapidly cross-link polyethyleneimine (PEI) and a thermoresponsive cellulose nanofiber (TRCNF). The latter was obtained by grafting N-isopropylacrylamide (NIPAm) on the cellulose nanofiber (CNF) through Ce (IV)-initiated free radical polymerization. The as-prepared TRCNF/PEIA simultaneously showed high capture capacity (6.74 mmol/g) with water at 25 °C and a low regeneration temperature (60 °C). A comparison of the adsorption–desorption properties of TRCNF/PEIA with those of the PEIA, which was prepared using a procedure similar to that of TRCNF/PEIA but without TRCNF, showed that the thermoresponsive property of PNIPAm and the synergy of the hydroxyl groups of TRCNF/PEIA could facilitate CO2 complete desorption from the adsorbent at 60 °C, which was the lowest regeneration temperature to maintain the high adsorption capacity (≥6 mmol/g) of the adsorbents, based on the literature reports.