Surface Modification of Activated Carbon Fibers for the Adsorption Capture of Carbon Dioxide in Flue Gas

Tetraethylenepentamine (TEPA) and K₂CO₃ were utilized as modifiers to optimize the surface properties of ACFs and enhance their CO₂ adsorption performance. The results show that the TEPA modification leads to an increase in the nitrogen content, while the K₂CO₃ modification enhances the proportion of oxygen elements in ACFs. Both unmodified and modified ACFs predominantly consist of carbon elements, accounting for over 80 wt.% of the total composition. TEPA modification can improve both the adsorption capacity and adsorption rate of CO₂, while K₂CO₃ modification only enhances the adsorption capacity. The modification using 4 wt.% exhibits an excellent CO₂ adsorption capacity of 27.6 mL/g, while the modification using 0.8 mol/L K₂CO₃ demonstrates a good CO₂ adsorption capacity of 28.1 mL/g. The simulation study reveals that the modified ACFs are more likely to bind with CO₂ molecules compared to unmodified ACFs, whereas TEPA-modified ACFs have almost the same CO₂ adsorption performance as K₂CO₃-modified ACFs.