Version 1
: Received: 28 February 2021 / Approved: 2 March 2021 / Online: 2 March 2021 (11:38:54 CET)
Version 2
: Received: 28 March 2021 / Approved: 29 March 2021 / Online: 29 March 2021 (16:20:16 CEST)
Thakor, G.S.; Zhang, N.; Santos, R.M. Sensing and Delineating Mixed-VOC Composition in the Air Using a Single Metal Oxide Sensor. Clean Technol.2021, 3, 519-533.
Thakor, G.S.; Zhang, N.; Santos, R.M. Sensing and Delineating Mixed-VOC Composition in the Air Using a Single Metal Oxide Sensor. Clean Technol. 2021, 3, 519-533.
Thakor, G.S.; Zhang, N.; Santos, R.M. Sensing and Delineating Mixed-VOC Composition in the Air Using a Single Metal Oxide Sensor. Clean Technol.2021, 3, 519-533.
Thakor, G.S.; Zhang, N.; Santos, R.M. Sensing and Delineating Mixed-VOC Composition in the Air Using a Single Metal Oxide Sensor. Clean Technol. 2021, 3, 519-533.
Abstract
Monitoring volatile organic compounds (VOCs) places a crucial role in environmental pollutants control and indoor air quality. In this study, a metal-oxide (MOx) sensor detector (used in a commercially available monitor) was employed to delineate the composition of air containing three common VOCs (ethanol, acetone and hexane) under various concentrations. Experiments with a single component and double components were conducted to investigate how the solvents interact with the metal oxide sensor. The experimental results revealed that the affinity between VOC and sensor was in the following order: acetone > ethanol > n-hexane. A mathematical model was developed, based on the experimental findings and data analysis, to convert the output resistance value of the sensor into concentration values, which in turn can be used to calculate a VOC-based air quality index. Empirical equations were established based on inferences of vapor composition versus resistance trends, and on an approach of using original and diluted air samples to generate two sets of resistance data per sample. The calibration of numerous model parameters allowed matching simulated curves to measured data. As such, the predictive mathematical model enabled quantifying not only the total concentration of sensed VOCs, but also estimating the VOC composition. This first attempt to obtain semi-quantitative data from a single MOx sensor, despite remaining selectivity challenges, is aimed at expanding the capability of mobile air pollutants monitoring devices.
Keywords
volatile organic compounds; air quality monitoring; metal oxide sensor; predictive mathematical model; gas composition estimation
Subject
Engineering, Automotive Engineering
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Commenter: Rafael M. Santos
Commenter's Conflict of Interests: Author