Regulation research on weak co-adsorption and nonsteady-state capture for C6H6/CO2 over carbon materials

Abstract

With the intention of capturing both benzene (C₆H₆) and carbon dioxide (CO₂) from indoor air, it is assuring of getting both C₆H₆ and CO₂ simultaneously adsorbed over activated carbon materials. Thus, in this study, how adsorption of C₆H₆ and CO₂ performs over single-wall carbon materials is minutely investigated via density function theory (DFT). Specifically speaking, direct electronic interaction between C₆H₆ and CO₂, co-adsorption features and nonsteady-state capture processes of C₆H₆/CO₂ over single-wall carbon nanotube (CNT) as well as regulation of CNTs towards more stable adsorption are main contents in this study. According to results, C₆H₆ and CO₂ are weakly mutually attracted because of limited electrostatic attraction forces and hydrogen-bond effects, which are also the major reason for consequent weak co-adsorption state over pure CNT. In the meantime, owing to repulsive forces of π-orbital electrons from pure CNT to C₆H₆, both of C₆H₆ and CO₂ could be only captured by pure CNT in nonsteady state. However, with phosphorus (P) and aluminum (Al) embedded as dopants, surficial electron distribution is altered to a large degree and local electron-enriched centers of modified CNTs are formed to enhance connection with C₆H₆/CO₂, especially stronger electrostatic positron–electron attraction and faster capture speeds from free-state to adsorption-state at relatively high temperatures. Overall, this study provides plentiful information of utilizing single-wall carbon materials for fast indoor air purification in a passive way.