Adsorption and desorption behavior of benzene and toluene on porous carbon monoliths

Highly porous carbon monoliths with good mechanical strength were prepared by the sol. gel polymerization of phenolic resin in oxidized polyacrylonitrile fiber felts, ambient drying, carbonization at 800 degrees C for 2 h and CO2 activation at 950 degrees C for 1 to 3 h. Their microstructure and pore structure were investigated by SEM, TEM and N-2 adsorption. Their adsorption/desorption performance for benzene and toluene was measured by the gravimetric method. It is found that the carbon monoliths have a typical fiber. reinforced aerogel structure and the sample activated for 3 h (ACM-3) has a well. developed microporous structure with a BET surface area of 1 872 m(2)/g and pore volume of 0. 97 cm(3)/g. ACM-3 shows high adsorption capacities of 117 and 287 m/g for 50 ppm benzene and toluene, respectively, and the fastest adsorption/desorption kinetics. The Langmuir, Freundlich and DR isotherm models are used to fit the experimental adsorption data and the DR model shows the highest correlation coefficient. Moreover, ACM-3 has an excellent cyclic stability. The as-prepared carbon monoliths are promising adsorbents for the adsorption of volatile or. ganic compounds in indoor air purification.