Grantee Research Project Results
2023 Progress Report: Enabling real-time, low-cost measurement of hazardous air pollutants
EPA Grant Number: R840425Title: Enabling real-time, low-cost measurement of hazardous air pollutants
Investigators: Isaacman-VanWertz, Gabriel , Kroll, Jesse H. , Papapostolou, Vasileios
Institution: Virginia Polytechnic Institute and State University , Massachusetts Institute of Technology
EPA Project Officer: Chung, Serena
Project Period: May 1, 2022 through May 12, 2025
Project Period Covered by this Report: May 1, 2023 through April 30,2024
Project Amount: $800,000
RFA: Measurement and Monitoring Methods for Air Toxics and Contaminants of Emerging Concern in the Atmosphere (2021) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics
Objective:
The overarching goal of this work is the development, optimization, and demonstration of a novel technique for measuring hazardous air pollutants. This project couples multiple approaches of low-cost sensing with new technologies for sample enrichment and fast chromatographic separation. Central to this technique is the measurement and chemical characterization of analytes using a multidimensional array of low-cost sensors for volatile organic gases (VOCs). This project overcomes the sensitivity and selectivity limitations of existing low-cost sensors by developing two new front-ends. First, a novel inlet will enrich the analytes within the sample flow in real time, improving sensitivity of the sensors. This will be followed by a rapid inline gas chromatography (GC) column to provide some analyte separation, greatly improving selectivity of the measurement, and enabling the identification and quantification of individual hazardous air pollutants. This project includes the demonstration and validation of the developed technologies by deployment alongside instrumentation at existing sites in southern California where emissions of hazardous air pollutants might be expected to occur.
Progress Summary:
This reporting period included significant progress on the central technologies being developed and included their initial successful integration. Development and evaluation of the enriching inlet is complete and published in the peer-reviewed scientific literature. Analyte concentrations were enhanced by up to a factor of 47 times in sample flows between 0.2 and 5 sccm (higher enrichment at lower flows), with a descriptive model able to predict enrichment as a function of operating conditions. The inline GC approach has been demonstrated at concentrations relevant to human health, and has been incorporated with low-cost sensors. Instrument response is predictable and not sensitive to operating parameters, though less-than-optimal chromatographic quality is observed and is being evaluated. An array of 12 sensors was challenged with complex ambient mixtures and advanced data analysis techniques were demonstrated to be able to provide understanding of complex mixtures of different compound classes – an approach expected to be critical in interpreting data from the detector array and useful for observed complex detector responses for some types of detectors when detecting even simple mixtures. Finally, a critical step toward a full prototype was achieved by coupling the in-line GC with low-cost sensors by overcoming technical hurdles to develop a custom manifold that is has been demonstrated with two of the sensor types used in the array, is scalable to multiple additional sensors, and functions at the low flows required for the enriching inlet. These results bring the project close to a complete prototype that incorporates all three developed technologies, which will be deployed for measurements of ambient air in the next reporting period. By addressing shortcomings in the sensitivity and selectivity of low-cost sensors, the tools and techniques developed as part of this project and demonstrated in this reporting period are expected to expand access to measurements of hazardous air pollutants by researchers and members of the community.
Future Activities:
Activities in the next reporting period will be focused on integrating the in-line GC with the sensor array and enriching inlet to yield a full prototype. In particular, the currently observed issues in chromatographic peak quality will be investigated and the existing manifold re-designed if necessary. Additional detectors will then be incorporated and tested on the fully integrated system. Using these data, we anticipate evaluating the number of detectors necessary to resolve chemically similar hazardous air pollutants, and expect the system to be tested at concentrations within the range targeted as concern for human health. Testing of a multiple-detector system with in-line GC on ambient samples is expected to occur within the upcoming reporting period. If successful, the system will be tested in the South Coast AQMD labs and may be deployed alongside existing instrumentation to further goals of the remaining tasks that have not yet been initiated.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
| Other project views: | All 2 publications | 2 publications in selected types | All 2 journal articles |
|---|
| Type | Citation | ||
|---|---|---|---|
|
|
Panji NS, Isaacman-VanWertz G. A novel inlet for enriching concentrations of reactive organic gases in low sampling flows. Atmospheric Measurement Techniques. 2023;16(19):4319-30. |
R840425 (2023) |
Exit |
Supplemental Keywords:
instrumentation, atmospheric gases, air quality, hazardous air pollutantsRelevant Websites:
none
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.