Toluene adsorption and capacity regeneration using zeolite-based monolith and activated carbon fiber felt

Abstract

Common adsorbents studied to remove volatile organic compounds (VOCs) from indoor air can release previously adsorbed VOCs back into the indoor space when the adsorbent is saturated or if the VOC concentration fluctuates. A durable adsorbent with a continuous regeneration strategy could prevent this recontamination of the indoor air and reduce adsorbent disposal waste. A deeper understanding of the adsorption and desorption behavior of VOC adsorbents is needed to create an efficient regeneration strategy. This study investigated the adsorption and thermal desorption behavior of toluene on two different adsorbents, (1) a zeolite-based adsorbent and (2) an activated carbon fiber (ACF) felt. Consistent adsorption behavior across a series of toluene concentrations was used to experimentally determine effective adsorption capacity. When the cumulative adsorption between thermal regeneration steps was maintained below the maximum effective capacity with 0% breakthrough, the zeolite-based adsorbent was found to effectively minimize passive desorption. The impact of regeneration feed conditions, such as inert, oxidizing, humidified air, on thermal desorption was examined. These conditions influenced desorption of the zeolite-based adsorbent but had minimal impact on the ACF felt adsorbent, which would lead to different regeneration schedules and methods for applications in buildings' heating, ventilation, and air conditioning (HVAC) systems.