Enhanced adsorption of CO2 on cellulose and chitosan surface by H2O Co-adsorption

Abstract Adsorption of CO2 on biopolymers such as cellulose (CELL) and chitosan (CS) attracts researchers’ interest, in particular, the aerogel formation with high surface area and unique physical properties. In this work, we studiedthe molecular adsorption of CO2 molecule on the CELL and CS surfaces by performing density functional theory (DFT) calculations, using dimeric and trimeric structures as model compounds. The structure of the individual CELL and CS along with the molecular adsorbed CO2 systems CELLCO2 and CSCO2 were investigated using B3LYP/6-311++G(d,p) level of theory. The interaction energy of CELLCO2 indicated a weak physical adsorption process, where CSCO2 showed higher binding energies. The co-adsorption of CO2 and H2O on CELL and CS surfaces was also investigated. The results showed that H2O stabilized the adsorption of the CO2 on CELL and CS surface through hydrogen bond (HB), where the adsorption energies increased in the presence of the H2O molecule. The stability of CELLCO2 and CSCO2 was supported by an increase in the charge transfer process. This result highlighted the role of the humidity for the stabilization of CO2 on biopolymers surface.