Tubular activated carbons made from cotton stalk for dynamic adsorption of airborne toluene

Monolithic tubular activated carbons were prepared from cotton stalks by chemical activation using phosphorous acid and zinc chloride and referred to as AC-P and AC-Z, respectively. These tubular carbons can be stacked into a honeycomb-like configuration, which has potential in the emission control of volatile organic compounds. Dynamic adsorption of toluene on the tubular activated carbons was tested. AC-P had a specific surface area of 1256 m(2)/g, 73.4% of which was contributed by mesopores; while AC-Z had a specific surface area of 795 m2/g, 60% of which was contributed by micropores. FTIR spectra revealed that AC-Z possessed less oxygen-containing polar groups than AC-P, which contributed to its higher hydrophobicity. TG analysis also suggested that less water was adsorbed on AC-Z. At a flow rate of 150 mL/min and toluene concentration of 1000 ppm, the dynamic toluene adsorption capacity of AC-P was as high as 328 mg/g under dry conditions owing to its high specific surface area; however, it decreased to only 94 mg/g under wet conditions (80% relative humidity, 25 degrees C) due to its hydrophilicity. In contrast, AC-Z having high hydrophobicity showed a dynamic toluene adsorption capacity of 258 mg/g under dry conditions, which remained at 221 mg/g under wet conditions. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.