Volatile methylsiloxanes (VMS) are a special kind of impurity that exist in biogas and seriously hamper its utilization; therefore, their removal has attracted great attention in recent years. Adsorption is the only technology that is currently capable of industrial-scale removal of VMS. In this research, three carbons with various porous structures, including ordered mesoporous carbon (OMC), activated carbon fiber (ACF) and granular activated carbon (GAC), were selected as potential adsorbents to investigate their adsorption properties toward hexamethyldisiloxane (L2), which is a typical linear VMS pollutant. The adsorption isotherms and kinetics of L2 on the three carbons were studied, and the isosteric heats of adsorption were calculated in accordance with the isotherms under different temperatures by using the Van't Hoff equation. Additionally, the influences of the topological structures of the carbons on the adsorption kinetics were compared. Generally, adsorption isotherms of the three carbons can be well-fitted by the Dubinin-Astakhov equation, and the variation of the isosteric heats and adsorption kinetics are presumed to be closely related to the pore sizes of the carbons. These new findings reveal the adsorption mechanisms of L2 on carbons and make it possible that the proper adsorption system is set up to fulfill higher removal efficiency.
Keywords: Activated carbon fiber; Adsorption; Granular activated carbon; Hexamethyldisiloxane; Ordered mesoporous carbon.
Copyright © 2020 Elsevier Ltd. All rights reserved.