Abstract
Owing to their high stability against corrosive gases, carbon-based adsorbents are preferentially used for the adsorptive removal of SO2. In the present study, SO2 adsorption on different carbon nanomaterials namely carbon nanohorns (CNHs), multiwalled carbon nanotubes (MWNTs), single-walled carbon nanotubes (SWNTs) and vertically aligned carbon nanotubes (VACNTs) are investigated and compared against the adsorption characteristics of activated carbon and graphene oxide (GO). A comprehensive overview of the adsorption behavior of this family of carbon adsorbents is given for the first time. The relative influence of surface area and functional groups on the SO2 adsorption characteristics is discussed. The isosteric heat of adsorption values are calculated to quantify the nature of the interaction between the SO2 molecule and the adsorbent. Most importantly, while chemisorption is found to dominate the adsorption behavior in activated carbon, SO2 adsorption on carbon nanomaterials occurs by a physisorption mechanism.
Highlights
Compared to the conventional techniques such as absorption in liquids, the adsorptive removal of environmentally toxic gases, e.g., SO2, offers several advantages such as ease of regeneration, low maintenance and simple plant design [1,2]
The calculated isosteric heat of adsorption value of ca. 71 kJ/mol at a loading of 1 mmol/g suggests that SO2 adsorbs on Norit R1 carbon by a chemisorption mechanism
A comparison of the adsorption characteristics of the different adsorbents at 1 bar suggests a linear relationship of SO2 uptake with BET specific surface area
Summary
Compared to the conventional techniques such as absorption in liquids, the adsorptive removal of environmentally toxic gases, e.g., SO2, offers several advantages such as ease of regeneration, low maintenance and simple plant design [1,2]. Sun et al investigated the SO2 adsorption characteristics of SWNTs, MWNTs and activated carbon at atmospheric pressure and at very low SO2 concentrations [16]. We have shown the successful application of VACNTs as a model structure for a combined theoretical and experimental investigation of gas adsorption in carbon materials [30,31].
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