The effect of operational conditions on the performance of granular ozone removal media: Statistical experimental design and kinetic modeling

Abstract

Ozone, a strong oxidizer, and a hazardous air pollutant can adversely affect human health and the environment; therefore, its concentration must be kept within a specific limit. Several ozone removal technologies are available for this purpose, which may be used under different operational conditions. Despite the selection flexibility that these technologies bring about, they raise the need to better understand the feasibility of each technique for various applications. Such broad perspective however is currently lacking due mainly to the cost and resources required for comprehensive studies. Using a statistical design approach, this study aims to address this important gap. The fractional factorial method, as a reliable statistical technique, was used to study the effect of ozone concentration, humidity level, airflow rate, and media volume on the ozone removal performance of common granular materials including different types of activated carbon (CL-A: coal-based, CS-B: coconut shell-based, IM-l-A: coal-based impregnated with KOH) and a catalyst (CAT-E). The role of individual parameters and their interactions were studied. The results show that depending on the physicochemical properties of the material, humidity could substantially improve or deteriorate its performance. Among the materials tested across all operational conditions, on average, CL-A showed the poorest performance (mean efficiency = 62%, standard deviation = 0.31), CS-B was highly sensitive to operational conditions (efficiency was varied from 25% to 100% at different humidity levels), IM-l-A showed the highest efficiency robustness among activated carbon media (mean efficiency = 77.6%, standard deviation = 0.20), and CAT-E featured the best performance (mean efficiency = 86.5%, standard deviation = 0.16). Additionally, the data were fitted into a packed bed kinetic model that elucidated physicochemical mechanisms underlying distinctive behaviours of each tested material.