Pore size Tuning of activated carbon fiber through chemical drilling and widening for adsorption of chemical warfare agent simulant

Activated carbon fiber has received significant interest as an excellent adsorbent for chemical warfare agents. While several studies have been conducted on improving its adsorption performance, there is insufficient research dedicated to improving adsorption performance through the selection of an optimal pore size. In this study, activated carbon fibers with pores smaller than 1.0 nm were developed through KOH reactivation and those with pores larger than 1.0 nm were developed through steam reactivation. Surface and structural analyses revealed that KOH reactivation formed pores through chemical drilling with potassium functioning as an activation agent, while steam reactivation formed pores through widening the interparticle space (etching outer layers of the carbon particles). Therefore, the pore size distributions of activated carbon fibers could be controlled through KOH or steam reactivation. The prepared reactivated carbon fibers were applied to the adsorption of dimethyl methylphosphonate (DMMP), a chemical warfare agent simulant, and the correlation between DMMP uptake and pore size was investigated. The adsorption of DMMP showed a close relation with the pore volume for a pore size of 1.3–2.2 nm, with the strongest correlation observed for a pore size of 1.6–1.9 nm. Steam reactivation is advantageous for increasing the pore volume for a pore size of 1.6–1.9 nm, thereby proving effective in enhancing the DMMP adsorption performance by 150% compared to the conventional activated carbon fiber.