Diffusion, Separation, and Buffering of Non-Steady-State VOCs Flow on Activated Carbon

Abstract

In this study, the diffusion, separation, and buffering of volatile organic compounds emitted in a non-steady state on activated carbon were studied. Ethanol and xylene, which have large differences in adsorption capacity and diffusion rate, were selected as the representative target pollutants of volatile organic compounds. In this paper, activated carbon with a certain intake concentration and adsorption equilibrium was chosen as the research object. The buffering effect of pulse load was studied. The buffering effect and influencing factors were analyzed. The Bangham equation proved to be a more effective tool in describing the dynamic processes of ethanol and xylene adsorption on activated carbon, indicating that pore diffusion was the rate-determining step in the adsorption process. R3 emerged as a more suitable criterion for evaluating non-steady-state emissions. Factors such as pulse time and pulse multiplier were influenced by Empty Bed Contact Time (EBCT), which collaborated with EBCT to impact the buffering performance of activated carbon. An EBCT of 4 cm was identified as the optimal bed height, with R3 reaching 1.48. Non-polar VOCs with chemically symmetric structures exhibited slower mass transfer rates compared to polar VOCs, resulting in larger adsorption capacities on activated carbon and better buffering performance.