10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Aerosol Spark Emission Spectrometer (ASES) for the Measurement of Trace Metals Concentration in Particulate Emissions from the Combustion of Coal in a Household Heating and Cooking Stove
NATHAN REED, Yixiang Zhang, Zhichao Li, Sameer Patel, Jiayu Li, Zehua Wang, Lina Zheng, Pramod Kulkarni, Pratim Biswas, Washington University in St. Louis
Abstract Number: 434 Working Group: Instrumentation
Abstract A recent study by the World Health Organization found that 92 % of the world’s population lives in regions with unsafe ambient air quality. This situation challenges us to identify the source of pollutants, investigate their properties, and understand how they affect health and the environment. Investigating the properties of pollutants, especially particulate matter (PM), is critical for understanding both their source and subsequent effects. Based on its chemical composition and physical characteristics, PM can be attributed to sources such as coal powerplants, vehicle emissions, or biomass combustion. Although the mass concentrations of PM (PM1, PM2.5, and PM10) are almost exclusively used to regulate air quality, other physical metrics, such as number concentration, surface area, and even chemical composition might be a better way to represent the health effects of PM [1].
The accessibility and affordability of instruments critically hinder the comprehensive characterization of PM. Low-cost and compact instruments are being developed to measure the characteristics of PM in real time. These measurements currently are limited to the aerosol physical properties such as mass concentration and size distribution [2, 3]. Low-cost portable instruments to capture organic and inorganic species have not yet been developed thus these measurements are usually done by collecting filter samples for off-line analysis. Instruments that could perform chemical analysis in situ would reduce sampling costs, logistical problems, and measurement artifacts from storage and transportation of filter samples.
This work focuses on a portable instrument, the aerosol spark emission spectrometer (ASES) for quantitative characterization of the elemental content of PM. This instrument employs atomic emission spectroscopy using spark microplasma as the excitation source [4, 5]. PM is collected on the tip of a cathode in a coaxial electrode system via a one-step charge-and-collect scheme using corona discharge [6]. The collected sample is then ablated and excited by the spark microplasma, and the resulting atomic emission is recorded by a broadband CCD spectrometer for elemental identification and quantification. The utility of the ASES is demonstrated in this study by applying it to measure elements present in PM emitted from a solid-fuel cooking and heating stove. These stoves are one of the biggest contributors of PM emissions in countries such as India and China. In addition to real-time measurements from the ASES, filter samples were collected and analyzed using an ICP-MS to assess the accuracy of the real-time performance. In addition to measuring the elemental composition, we also used various real-time instruments to track the different phases of the burn-cycle in the stove, and to correlate physical PM metrics and elemental composition measurements.
References: 1. Leavey, A., et al., Organic and inorganic speciation of particulate matter formed during different combustion phases in an improved cookstove. Environmental Research, 2017. 158: p. 33-42. 2. Patel, S., et al., Spatio-temporal measurement of indoor particulate matter concentrations using a wireless network of low-cost sensors. Environmental Research, 2017. 152: p. 59-65. 3. Wang, Y., et al., Laboratory Evaluation and Calibration of Three Low-Cost Particle Sensors for PM Measurement. Aerosol Science and Technology, 2015. 49(11): p. 1063-1077. 4. Diwakar, Prasoon, and Pramod Kulkarni. Measurement of elemental concentration of aerosols using spark emission spectroscopy. Journal of analytical atomic spectrometry 2012. 27(7): 1101-1109. 5. Zheng, L, et al. Near real-time measurement of carbonaceous aerosol using microplasma spectroscopy: Application to measurement of carbon nanomaterials. Aerosol Science and Technology 2016. 50(11): 1155-1166. 6. Zheng, L, et al. Characterization of an aerosol microconcentrator for analysis using microscale optical spectroscopies. Journal of Aerosol Science 2017. 104: 66-78.