Design, synthesis, and physicochemical study of a biomass-derived CO sorbent 2,5-furan-bis(iminoguanidine).

In this study, the concept of biomass-based direct air capture is proposed, and the aminoguanidine CO chemical sorbent 2,5-furan-bis(iminoguanidine) (FuBIG) was designed, synthesized, and elucidated for the physicochemical properties in the process of CO capture and release. Results showed that the aqueous solution of FuBIG could readily capture CO from ambient air and provided an insoluble tetrahydrated carbonate salt FuBIGH(CO) (HO) with a second order kinetics. Hydrogen binding modes of iminoguanidine cations with carbonate ions and water were identified by single-crystal X-ray diffraction analysis. Equilibrium constant (K) and the enthalpies (ΔH) for CO absorption/release were obtained by thermodynamic and kinetic analysis (K = 5.97 × 10, ΔH = -116.1 kJ/mol, ΔH = 209.31 kJ/mol), and the CO-release process was conformed to the geometrical phase-boundary model (1-(1-α) = kt). It was found that the FuBIGH(CO) (HO) can release CO spontaneously in DMSO without heating. Zebrafish models revealed a favorable biocompatibility of FuBIG.