Excitation–Emission Matrix Spectroscopy for Analysis of Chemical Composition of Combustion Generated Particulate Matter

Mahamuni, Gaurav; Rutherford, Jay; Davis, Justin; Molnar, Eric; Posner, Jonathan D.; Seto, Edmund; Korshin, Gregory V.; Novosselov, Igor

doi:10.1021/acs.est.0c01110

Cited by 37 publications

(16 citation statements)

References 103 publications

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“…Mahamuni et al reported the wood smoke samples' chemical composition, calculating that the total mass of 16 EPA PAHs was~20-25 ng/μg of soot, see S6 Fig in S1 File. About 75% (by weight) of PAHs in the sample were high species with MW>202 g/mol (i.e., larger than Pyrene) [13]. TOC analysis was not performed here but typically reported TOC values for cookstoves are greater than 50% depending on the type of the cookstove and operational conditions [38][39][40].…”

Section: Plos Onementioning

confidence: 99%

“…EEM has been previously used for analysis of combustion PM [28][29][30][31]. The challenges of deconvolving the overlapping peaks can be addressed by data-driven techniques [13,32]. However, similar to the standard laboratory methods, EEM analysis of aerosol samples suffers labor-intensive steps involving sample collection on filters, solvent extraction, filtration, and serial dilutions, which is not amenable for miniaturized sensors.…”

Section: Introductionmentioning

confidence: 99%

“…The size of PAHs in young soot has been approximated by molecular dynamics simulations to be between four rings (Pyrene) and 19 rings (circumcoronene) [ 8 , 9 ]. The PAHs participating in PM formation or components condensed on PM during the secondary growth [ 10 , 11 ] can be oxidized in the flame [ 12 ]; however, a significant organic fraction is retained by the particle, especially in the low temperature (incomplete) combustion [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

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Solid-phase excitation-emission matrix spectroscopy for chemical analysis of combustion aerosols

Mahamuni

Rutherford

et al. 2021

PLoS ONE

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Exposure to ultrafine combustion aerosols such as particulate matter (PM) from residential woodburning, forest fires, cigarette smoke, and traffic emission have been linked to adverse health outcomes. Excitation-emission matrix (EEM) spectroscopy presents a sensitive and cost-effective alternative for analysis of PM organic fraction. However, as with other analytical chemistry methods, the miniaturization is hindered by a solvent extraction step and a need for benchtop instrumentation. We present a methodology for collecting and in-situ analysis of airborne nanoparticles that eliminates labor-intensive sample preparation and miniaturizes the detection platform. Nanoparticles are electrostatically collected onto a transparent substrate coated with solid-phase (SP) solvent—polydimethylsiloxane (PDMS). The PM organic fraction is extracted into PDMS and analyzed in-situ, thus avoiding liquid-phase extraction. In the SP-EEM analysis, we evaluated external and internal excitation schemes. Internal excitation shows the lowest scattering interference but leads to signal masking from PDMS fluorescence for λ<250nm. The external excitation EEM spectra are dependent on the excitation light incident angle; ranges of 30–40° and 55–65° show the best results. SP-EEM spectra of woodsmoke and cigarette smoke samples are in good agreement with the EEM spectra of liquid-phase extracts. The SP-EEM technique can be used to develop wearable sensors for exposure assessments and environmental monitoring.

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Section: Plos Onementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Solid-phase excitation-emission matrix spectroscopy for chemical analysis of combustion aerosols

Mahamuni

Rutherford

et al. 2021

PLoS ONE

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“…Hitherto, prior works focused on the variability of the overall BrC mass fractions and their overall light-absorption properties measured at various settings in laboratory flame experiments, such as flame temperature, dilution, equivalence ratio, and height above the burner distance. , Chemical species in flame emissions may span hundreds to thousands of organic compounds that usually make up a smaller mass fraction of OC compared to that of the BC generated in flames . Of the OC species formed in the flame combustion of ethylene, ,− benzene, , toluene, and an A-1 jet fuel surrogate, , large-molecular-weight PAHs and their oxidized byproducts were reported, as well as hydrocarbons with more aliphatic-like structures and higher oxygen content. Additional microscopic imaging of individual particles from these studies , showed their liquid-like appearance and morphological properties, indicating a graphitic core and a more aliphatic shell.…”

Section: Introductionmentioning

confidence: 99%

Molecular Composition and the Optical Properties of Brown Carbon Generated by the Ethane Flame

West

Hettiyadura

Darmody

et al. 2020

ACS Earth Space Chem.

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Atmospheric “Brown Carbon” (BrC) is a complex mixture of organic compounds with diverse composition and variability of its light-absorbing properties. BrC formed by incomplete combustion of fossil fuels and biomass has been shown to be an important contributor to the light absorption by atmospheric aerosols. Previous reports provided substantial molecular information of BrC related to biomass burning emissions; however, very few studies describe BrC generated from hydrocarbon fuel combustion. The work presented here is the first study that identifies and characterizes BrC formed in the controlled flame combustion of ethane, one of the most basic hydrocarbon fuels. To understand the molecular composition and optical properties of BrC, we used an analytical platform that includes high-performance liquid chromatography (HPLC) coupled to photodiode array (PDA) detection, followed by dopant-assisted atmospheric pressure photoionization (APPI) and high-resolution mass spectrometry (HRMS). For this study, six soot samples were generated in a custom-built inverted gravity flame reactor (IGFR) at different combustion settings. The temperature of the diffusion flame was controlled by fuel dilution with argon (up to 80% v/v) and was measured to be in the range of 1750–1950 K. Basic characterization of the samples (i.e., mass loading, OC/soot ratio) was employed, followed by molecular speciation of BrC chromophores. A vast majority of BrC chromophores identified in these samples are oxygenated polycyclic aromatic hydrocarbons (O-PAHs) and unsubstituted PAHs. Nearly 90% of the total BrC absorbance was attributed to approximately equal contributions from the groups of: O-PAHs, low- and high-molecular-weight PAHs referred as PAH < BaP and PAH > BaP (i.e., smaller and larger than Benzo[a]pyrene (BaP), respectively). The mass absorption coefficient (MACbulk) measured at λ350 nm for the BrC fraction of aerosol emitted from the hottest undiluted flame (T max = 1946 K) was 0.49 m2 g–1, while 0.004 m2 g–1 was measured for aerosol emitted from the colder flame (T max = 1863 K, 67% dilution). The optical properties of BrC generated in the hottest flame are comparable to previous measurements of BrC generated from gasoline combustion of motor vehicles.

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“…22 These system characteristics have been leveraged for material synthesis and studies of particle formation and growth in dilute low temperature flames. [23][24][25] While some hydrothermal flame reactors are operated in the upright configuration, 26 these provide high flame temperatures but very low residence time. Most SCWO reactors utilize the downflow arrangement 5,12,[27][28][29] to achieve long residence times and uniform temperature profiles needed for hazardous waste destruction.…”

Section: Introductionmentioning

confidence: 99%

Design of a Small-Scale Supercritical Water Oxidation Reactor. Part I: Experimental Performance and Characterization

Moore¹,

Pinkard

Purohit³

et al. 2020

Preprint

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A small-scale supercritical water oxidation reactor is designed and fabricated to study the destruction of hazardous wastes. The downward bulk flow is heated with the introduction of pilot fuel (ethanol/water mixture), and oxidant (H2O2/water mixture). Both streams are introduced coaxially. The fuel dilution is varied from 2 to 7 mol% ethanol/water, and the oxidant-to-fuel stoichiometric equivalence ratio (ΦAF), is varied from 1.1 to 1.5. Higher ethanol concentrations in the pilot fuel stream and operation near-stoichiometric results in a more stratified temperature profile, i.e., highest local fluid temperatures near the top and the lowest temperatures at the bottom of the reactor. Steady operation at 603.5 °C is achieved with a nominal residence time of 25.3 s at 7 mol% fuel dilution and ΦAF of 1.1. At the lowest pilot fuel dilution (2 mol%), the temperature profile is nearly uniform, approaching a distributed reaction regime.

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Excitation–Emission Matrix Spectroscopy for Analysis of Chemical Composition of Combustion Generated Particulate Matter

Cited by 37 publications

References 103 publications

Solid-phase excitation-emission matrix spectroscopy for chemical analysis of combustion aerosols

Solid-phase excitation-emission matrix spectroscopy for chemical analysis of combustion aerosols

Molecular Composition and the Optical Properties of Brown Carbon Generated by the Ethane Flame

Design of a Small-Scale Supercritical Water Oxidation Reactor. Part I: Experimental Performance and Characterization

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