Adsorption characteristics of benzene on resin-based activated carbon under humid conditions

VOCs removal under humid conditions is an important issue in the various industries. However, adsorption capacity of commercial coconut-shell–based activated carbon (CAC) is diminished considerably in high relative humidity. In this study, we prepared resin-based activated carbon (RAC) from strong cation-exchange resins consisting of polystyrene with divinylbenzene, and investigated benzene adsorption characteristics under humid conditions. The results of water isotherm and breakthrough experiments revealed that RAC adsorbed no water vapor in low P/P0 region and the amount of adsorbed benzene did not decrease significantly with the addition of water vapor, indicating high water resistance compared to CAC. This high resistance of RAC to water vapor can be contributed by the low content of hydrophilic sites (metal impurity and surface oxygen), confirmed by XPS and ICP results. The relationship between RAC porosity and benzene adsorption under humid conditions was also investigated. Benzene adsorption under humid conditions was influenced significantly by the narrow micropore volume of RAC. As the narrow micropore volume of RAC decreased, the adsorption of water vapor was inhibited, so that the decline in the time of breakthrough at relative humidity at 70% was considerably alleviated from 44 to 1.2%.