Benzene Adsorption from Dry and Humid Air on Activated Carbons from Japanese Cypress Wood Prepared by CO2 and K2CO3 Activation

• Main Authors: Veksha, Andrei, Uddin, Md. Azhar, Sasaoka, Eiji, Kato, Yoshiei
• Other Authors: Nanyang Environment and Water Research Institute
• Format: Article
• Language: English
• Published: 2017
• Subjects: Activated carbon; Benzene adsorption
• Online Access: https://hdl.handle.net/10356/83335; http://hdl.handle.net/10220/42518
• Institution: Nanyang Technological University

Activated carbons (ACs) were prepared by physical (CO2) and chemical (K2CO3) activation of wood (Japanese cypress). Porous properties of the ACs, such as BET surface area and micropore volumes Vmic(N2) and Vmic(CO2), were characterized by N2 and CO2 adsorption isotherms. Short activation times caused formation of micropores with sizes smaller than 0.7 nm, which had a restricted access for N2 molecules. As a result, the ACs prepared through short activation time exhibited Vmic(N2) smaller than Vmic(CO2). The ACs were used for benzene adsorption at 5 ppmv concentration and relative humidities (RHs) of 0, 50 and 70 %. The largest benzene adsorption capacities at these RHs were exhibited by the AC prepared with K2CO3 activation at 800 °C. At RH 0 %, the benzene adsorption on the ACs was governed by Vmic(N2), when it was smaller than Vmic(CO2), and by Vmic(CO2), when it was smaller than Vmic(N2). The lower determination coefficients for the relationship between benzene uptake by the ACs and the volume of micropores at RHs 50 and 70 % compared to RH 0 % were attributed to the increased influence of surface chemistry of the ACs in the presence of moisture. In particular, the benzene adsorption at RHs 50 and 70 % was detrimentally affected by larger amounts of ash and surface oxygen groups.