(152e) Assessment of Residual Life of a Gas Filter Using Carbon-Nanotube Gas Sensors

A gas-filtration system filled with porous adsorbent is one of the most useful tools for reducing the amount of toxic volatile organic compounds released to the environment. However, it is challenging to assess the residual life of a filtration system and predict the time to replace the filter. In this study, we have shown how to evaluate the residual life of a gas-filtration system by embedding gas sensors into the system. Accordingly, chemiresistive gas sensors were fabricated via the deposition of patterned electrodes on a thin film of carbon nanotubes (CNTs). Multiple sensors were sequentially installed in the gas filter along the gas-flow direction. Dimethyl methylphosphonate, and ammonia were used to form a toxic gas model, and we observed the real-time changes in the resistance of the CNTs, which are highly sensitive to the adsorption of gas molecules because of their one-dimensional structure with high surface-to-volume ratio. The sensors responded sequentially as the toxic gases broke through the bed, and these responses could be correlated to the breakthrough curve of the toxic gases, obtained using gas chromatography and FT-IR. Here the properties of the CNT sensor can be potentially tuned by surface chemistry for the sensitive and selective detection of a target organic compound. Therefore, the approach reported herein can be useful for real-time assessment of the residual life of various gas-filtration systems.