Surface chemical characterization using AES/SAM and ToF-SIMS on KOH-impregnated activated carbon by selective adsorption of NO_x

KOH-impregnated activated carbon (K-IAC) was studied as a NO_x adsorbent. When adsorbing NO₂/air to K-IAC, as the concentration increases, the removal efficiency relatively decreases because the function of the selective adsorption site for NO_x is lost faster. By using AES/SAM and ToF-SIMS, we examined the chemical characteristics created on K-IAC through adsorption of NO_x. Oxide crystals formed on the surface of K-IAC after adsorption of NO_x was a result of the chemical bond among K, N, and O. KNO₃ was predominantly distributed on the external surface, and the pore of K-IAC showed blocking from the crystal growth of KNO₃. The results showed that surface basic OH^-, well developed on the surface because of KOH impregnation, acts as a selective adsorption site. This study pointedly illustrates selective adsorption behavior from strong chemical interaction between NO_x and K-IAC.