Application of a Gas Sensor Array to Effectiveness Monitoring of Air Contaminated with Toluene Vapors Absorption Process

Abstract

This article demonstrates the application of a gas sensor array to monitor the effectiveness of the absorption process of air stream purification from odorous compounds (toluene vapors). A self-constructed matrix consisting of five commercially available gas sensors was used. Multiple linear regression (MLR) was selected as the statistical technique used to calibrate the matrice. Gas chromatography coupled with a flame ionization detector (GC-FID) was used as a reference analytical technique, which enabled to obtain reliable quantitative determinations of toluene concentration in the samples. A commercially available absorption liquid dedicated to non-polar compounds was used as an absorbent. The process was carried out in two identical systems: in first, pure toluene was absorbed and in the second, toluene vapor contaminated with acetone. This approach allowed verifying the selectivity of the prepared MLR calibration model for process control in the case of the presence of more or less expected pollutants in the treated gas. The results obtained with the gas sensor array were related to the reference technique and they confirm the usefulness and advisability of using these devices to monitor the absorption processes as a cheaper and more time-efficient alternative to chromatographic methods. The root mean square error (RMSE) in absorptivity determination between the results received with the analytical and sensor techniques was 0.019 and 0.041 when treating pure toluene vapors and its vapors with acetone, respectively. Compared to instrumental techniques, sensor matrices are technologically less complex, useful for laboratory purposes, as well as showing application potential for field studies. However, it is necessary to develop more sensitive and selective chemical gas sensor arrays and better master advanced data processing and identification techniques