Abstract

This study focuses on ozone removal technologies and their performance in various conditions. Ozone is a highly reactive gas and a critical air pollutant, with a permissible workplace level of 100 ppb over 8 hours, according to OSHA. To address the risks associated with high outdoor ozone concentrations and active ozone emission sources, the use of ozone removal technologies is essential.
Various air treatment technologies, such as activated carbon-based media, and catalytic and photocatalytic decomposition systems, have been employed for ozone removal. However, there is limited insight into choosing the best technology based on specific application requirements. This study aims to fill that gap by systematically evaluating ozone removal using granular activated carbon (AC) and granular manganese oxide-cuprous oxide catalysts. The study found that coconut shell-based AC has substantial ozone removal capacity at moderate and mild concentration levels (<200 ppm, >95% efficiency), even surpassing the catalyst. However, all ACs experience deactivation at high concentrations. Catalysts, on the other hand, exhibit a gradual decline in active sites over time. The material properties were found to be closely linked to the ozone removal capacity.
To gain a broader perspective on ozone removal technology feasibility, a statistical approach using the fractional factorial method was employed. This approach considered ozone concentration, humidity level, airflow rate, and media volume, and their effects on the performance of different granular materials. The study revealed that humidity can significantly affect the performance of materials, depending on their physicochemical properties. Among the tested materials, the granular MnOx-based catalyst (CAT-E) demonstrated the best overall performance.
The research also addressed the deactivation issue of MnOx-based catalysts caused by water molecules, particularly at high humidity levels. Physicochemical modifications were investigated through synthesis methods and metal doping. These modifications improved the efficiency of the catalysts, with Ce-doped catalysts showing promising results. However, prolonged exposure to high humidity led to efficiency loss (at 80% RH <20% efficiency 6 h post exposure). To overcome this, a novel modification technique involving a hydrophobic polymer (poly(vinylidene fluoride)) mixed with catalytic media was employed, resulting in significantly enhanced performance (at 80% RH >50% efficiency 6 h post exposure).
Overall, this study sheds light on ozone removal technologies, their performance under different conditions, and potential modifications to enhance efficiency. These findings have implications for improving ozone removal systems in various applications.