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Articles 1 - 23 of 23
Full-Text Articles in Chemistry
Application Of A Small Unmanned Aerial System To Measure Ammonia Emissions From A Pilot Amine-Co2 Capture System, Travis J. Schuyler, Bradley Irvin, Keemia Abad, Jesse G. Thompson, Kunlei Liu, Marcelo I. Guzman
Application Of A Small Unmanned Aerial System To Measure Ammonia Emissions From A Pilot Amine-Co2 Capture System, Travis J. Schuyler, Bradley Irvin, Keemia Abad, Jesse G. Thompson, Kunlei Liu, Marcelo I. Guzman
Chemistry Faculty Publications
The quantification of atmospheric gases with small unmanned aerial systems (sUAS) is expanding the ability to safely perform environmental monitoring tasks and quickly evaluate the impact of technologies. In this work, a calibrated sUAS is used to quantify the emissions of ammonia (NH3) gas from the exit stack a 0.1 MWth pilot-scale carbon capture system (CCS) employing a 5 M monoethanolamine (MEA) solvent to scrub CO2 from coal combustion flue gas. A comparison of the results using the sUAS against the ion chromatography technique with the EPA CTM-027 method for the standard emission sampling of NH3 …
Production Of Singlet Oxygen (1O2) During The Photochemistry Of Aqueous Pyruvic Acid: The Effects Of Ph And Photon Flux Under Steady-State O2(Aq) Concentration, Alexis J. Eugene, Marcelo I. Guzman
Production Of Singlet Oxygen (1O2) During The Photochemistry Of Aqueous Pyruvic Acid: The Effects Of Ph And Photon Flux Under Steady-State O2(Aq) Concentration, Alexis J. Eugene, Marcelo I. Guzman
Chemistry Faculty Publications
The photochemistry of pyruvic acid (PA) in aqueous atmospheric particles contributes to the production of secondary organic aerosols. This work investigates the fate of ketyl and acetyl radicals produced during the photolysis (λ ≥ 305 nm) of 5-100 mM PA under steady state [O2(aq)] = 260 μM (1.0 ≤ pH ≤ 4.5) for photon fluxes between 1 and 10 suns. The radicals diffuse quickly into the water/air interface of microbubbles and react with dissolved O2 to produce singlet oxygen (1O2*). Furfuryl alcohol is used to trap and bracket the steady-state production of …
Monitoring Tropospheric Gases With Small Unmanned Aerial Systems (Suas) During The Second Cloudmap Flight Campaign, Travis J. Schuyler, Sean C. C. Bailey, Marcelo I. Guzman
Monitoring Tropospheric Gases With Small Unmanned Aerial Systems (Suas) During The Second Cloudmap Flight Campaign, Travis J. Schuyler, Sean C. C. Bailey, Marcelo I. Guzman
Chemistry Faculty Publications
Small unmanned aerial systems (sUAS) are a promising technology for atmospheric monitoring of trace atmospheric gases. While sUAS can be navigated to provide information with higher spatiotemporal resolution than tethered balloons, they can also bridge the gap between the regions of the atmospheric boundary layer (ABL) sampled by ground stations and manned aircraft. Additionally, sUAS can be effectively employed in the petroleum industry, e.g., to constrain leaking regions of hydrocarbons from long gasoducts. Herein, sUAS are demonstrated to be a valuable technology for studying the concentration of important trace tropospheric gases in the ABL. The successful detection and quantification of …
Crystal Structure Of Zymonic Acid And A Redetermination Of Its Precursor, Pyruvic Acid, Dominik Heger, Alexis J. Eugene, Sean R. Parkin, Marcelo I. Guzman
Crystal Structure Of Zymonic Acid And A Redetermination Of Its Precursor, Pyruvic Acid, Dominik Heger, Alexis J. Eugene, Sean R. Parkin, Marcelo I. Guzman
Chemistry Faculty Publications
The structure of zymonic acid (systematic name: 4-hydroxy-2-methyl-5-oxo-2,5-dihydrofuran-2-carboxylic acid), C6H6O5, which had previously eluded crystallographic determination, is presented here for the first time. It forms by intramolecular condensation of parapyruvic acid, which is the product of aldol condensation of pyruvic acid. A redetermination of the crystal structure of pyruvic acid (systematic name: 2-oxopropanoic acid), C3H4O3, at low temperature (90 K) and with increased precision, is also presented [for the previous structure, see: Harata et al. (1977). Acta Cryst. B33, 210–212]. In zymonic acid, the hydroxylactone ring …
The Effects Of Reactant Concentration And Air Flow Rate In The Consumption Of Dissolved O2 During The Photochemistry Of Aqueous Pyruvic Acid, Alexis J. Eugene, Marcelo I. Guzman
The Effects Of Reactant Concentration And Air Flow Rate In The Consumption Of Dissolved O2 During The Photochemistry Of Aqueous Pyruvic Acid, Alexis J. Eugene, Marcelo I. Guzman
Chemistry Faculty Publications
The sunlight photochemistry of the organic chromophore pyruvic acid (PA) in water generates ketyl and acetyl radicals that contribute to the production and processing of atmospheric aerosols. The photochemical mechanism is highly sensitive to dissolved oxygen content, [O2(aq)], among other environmental conditions. Thus, herein we investigate the photolysis (λ ≥ 305 nm) of 10–200 mM PA at pH 1.0 in water covering the relevant range 0 ≤ [O2(aq)] ≤ 1.3 mM. The rapid consumption of dissolved oxygen by the intermediate photolytic radicals is monitored in real time with a dissolved oxygen electrode. …
Photocatalytic Activity: Experimental Features To Report In Heterogeneous Photocatalysis, Md. Ariful Hoque, Marcelo I. Guzman
Photocatalytic Activity: Experimental Features To Report In Heterogeneous Photocatalysis, Md. Ariful Hoque, Marcelo I. Guzman
Chemistry Faculty Publications
Heterogeneous photocatalysis is a prominent area of research with major applications in solar energy conversion, air pollution mitigation, and removal of contaminants from water. A large number of scientific papers related to the photocatalysis field and its environmental applications are published in different journals specializing in materials and nanomaterials. However, many problems exist in the conception of papers by authors unfamiliar with standard characterization methods of photocatalysts as well as with the procedures needed to determine photocatalytic activities based on the determination of “apparent quantum efficiencies” within a wavelength interval or “apparent quantum yields” in the case of using monochromatic …
An Overview Of Dynamic Heterogeneous Oxidations In The Troposphere, Elizabeth A. Pillar-Little, Marcelo I. Guzman
An Overview Of Dynamic Heterogeneous Oxidations In The Troposphere, Elizabeth A. Pillar-Little, Marcelo I. Guzman
Chemistry Faculty Publications
Due to the adverse effect of atmospheric aerosols on public health and their ability to affect climate, extensive research has been undertaken in recent decades to understand their sources and sinks, as well as to study their physical and chemical properties. Atmospheric aerosols are important players in the Earth’s radiative budget, affecting incoming and outgoing solar radiation through absorption and scattering by direct and indirect means. While the cooling properties of pure inorganic aerosols are relatively well understood, the impact of organic aerosols on the radiative budget is unclear. Additionally, organic aerosols are transformed through chemical reactions during atmospheric transport. …
Enhanced Acidity Of Acetic And Pyruvic Acids On The Surface Of Water, Alexis J. Eugene, Elizabeth A. Pillar, Agustín J. Colussi, Marcelo I. Guzman
Enhanced Acidity Of Acetic And Pyruvic Acids On The Surface Of Water, Alexis J. Eugene, Elizabeth A. Pillar, Agustín J. Colussi, Marcelo I. Guzman
Chemistry Faculty Publications
Understanding the acid–base behavior of carboxylic acids on aqueous interfaces is a fundamental issue in nature. Surface processes involving carboxylic acids such as acetic and pyruvic acids play roles in (1) the transport of nutrients through cell membranes, (2) the cycling of metabolites relevant to the origin of life, and (3) the photooxidative processing of biogenic and anthropogenic emissions in aerosols and atmospheric waters. Here, we report that 50% of gaseous acetic acid and pyruvic acid molecules transfer a proton to the surface of water at pH 2.8 and 1.8 units lower than their respective acidity constants pKa …
Cross Photoreaction Of Glyoxylic And Pyruvic Acids In Model Aqueous Aerosol, Sha-Sha Xia, Alexis J. Eugene, Marcelo I. Guzman
Cross Photoreaction Of Glyoxylic And Pyruvic Acids In Model Aqueous Aerosol, Sha-Sha Xia, Alexis J. Eugene, Marcelo I. Guzman
Chemistry Faculty Publications
Aerosols of variable composition, size, and shape are associated with public health concerns as well as with light-particle interactions that play a role in the energy balance of the atmosphere. Photochemical reactions of 2-oxocarboxylic acids in the aqueous phase are now known to contribute to the total secondary organic aerosol (SOA) budget. This work explores the cross reaction of glyoxylic acid (GA) and pyruvic acid (PA) in water, the two most abundant 2-oxocarboxylic acids in the atmosphere, under solar irradiation and dark thermal aging steps. During irradiation, PA and GA are excited and initiate proton-coupled electron transfer or hydrogen abstraction …
Unmanned Aerial Systems For Monitoring Trace Tropospheric Gases, Travis J. Schuyler, Marcelo I. Guzman
Unmanned Aerial Systems For Monitoring Trace Tropospheric Gases, Travis J. Schuyler, Marcelo I. Guzman
Chemistry Faculty Publications
The emission of greenhouse gases (GHGs) has changed the composition of the atmosphere during the Anthropocene. Accurately documenting the sources and magnitude of GHGs emission is an important undertaking for discriminating the contributions of different processes to radiative forcing. Currently there is no mobile platform that is able to quantify trace gases at altitudes(UASs) can be deployed on-site in minutes and can support the payloads necessary to quantify trace gases. Therefore, current efforts combine the use of UASs available on the civilian market with inexpensively designed analytical systems for monitoring atmospheric trace gases. In this context, this perspective introduces the …
Oxidation Of Substituted Catechols At The Air-Water Interface: Production Of Carboxylic Acids, Quinones, And Polyphenols, Elizabeth A. Pillar, Marcelo I. Guzman
Oxidation Of Substituted Catechols At The Air-Water Interface: Production Of Carboxylic Acids, Quinones, And Polyphenols, Elizabeth A. Pillar, Marcelo I. Guzman
Chemistry Faculty Publications
Anthropogenic activities contribute benzene, toluene, and anisole to the environment, which in the atmosphere are converted into the respective phenols, cresols, and methoxyphenols by fast gas-phase reaction with hydroxyl radicals (HO(•)). Further processing of the latter species by HO(•) decreases their vapor pressure as a second hydroxyl group is incorporated to accelerate their oxidative aging at interfaces and in aqueous particles. This work shows how catechol, pyrogallol, 3-methylcatechol, 4-methylcatechol, and 3-methoxycatechol (all proxies for oxygenated aromatics derived from benzene, toluene, and anisole) react at the air-water interface with increasing O3(g) during τc ≈ 1 μs contact time and contrasts their …
Catalyzed Synthesis Of Zinc Clays By Prebiotic Central Metabolites, Marcelo I. Guzman, Ruixin Zhou, Kaustuv Basu, Hyman Hartman, Christopher J. Matocha, S. Kelly Sears, Hajatollah Vali
Catalyzed Synthesis Of Zinc Clays By Prebiotic Central Metabolites, Marcelo I. Guzman, Ruixin Zhou, Kaustuv Basu, Hyman Hartman, Christopher J. Matocha, S. Kelly Sears, Hajatollah Vali
Chemistry Faculty Publications
How primordial metabolic networks such as the reverse tricarboxylic acid (rTCA) cycle and clay mineral catalysts coevolved remains a mystery in the puzzle to understand the origin of life. While prebiotic reactions from the rTCA cycle were accomplished via photochemistry on semiconductor minerals, the synthesis of clays was demonstrated at low temperature and ambient pressure catalyzed by oxalate. Herein, the crystallization of clay minerals is catalyzed by succinate, an example of a photoproduced intermediate from central metabolism. The experiments connect the synthesis of sauconite, a model for clay minerals, to prebiotic photochemistry. We report the temperature, pH, and concentration dependence …
Reactivity Of Ketyl And Acetyl Radicals From Direct Solar Actinic Photolysis Of Aqueous Pyruvic Acid, Alexis J. Eugene, Marcelo I. Guzman
Reactivity Of Ketyl And Acetyl Radicals From Direct Solar Actinic Photolysis Of Aqueous Pyruvic Acid, Alexis J. Eugene, Marcelo I. Guzman
Chemistry Faculty Publications
The variable composition of secondary organic aerosols (SOA) contributes to the large uncertainty for predicting radiative forcing. A better understanding of the reaction mechanisms leading to aerosol formation such as for the photochemical reaction of aqueous pyruvic acid (PA) at λ ≥ 305 nm can contribute to constrain these uncertainties. Herein, the photochemistry of aqueous PA (5-300 mM) continuously sparged with air is re-examined in the laboratory under comparable irradiance at 38° N at noon on a summer day. Several analytical methods are employed to monitor the time series of the reaction, including (1) the derivatization of carbonyl (C═O) functional …
Nitrate Radicals And Biogenic Volatile Organic Compounds: Oxidation, Mechanisms And Organic Aerosol, Nga Lee Ng, Steven S. Brown, Alexander T. Archibald, Elliot Atlas, Ronald C. Cohen, John N. Crowley, Douglas A. Day, Neil M. Donahue, Juliane L. Fry, Hendrik Fuchs, Robert J. Griffin, Marcelo I. Guzman, Hartmut Hermann, Alma Hodzic, Yoshiteru Iinuma, José L. Jimenez, Astrid Kiendler-Scharr, Ben H. Lee, Deborah J. Luecken, Jingqiu Mao, Robert Mclaren, Anke Mutzel, Hans D. Osthoff, Bin Ouyang, Benedicte Picquet-Varrault, Ulrich Platt, Havala O. T. Pye, Yinon Rudich, Rebecca H. Schwantes, Manabu Shiraiwa, Jochen Stutz, Joel A. Thornton, Andreas Tilgner, Brent J. Williams, Rahul A. Zaveri
Nitrate Radicals And Biogenic Volatile Organic Compounds: Oxidation, Mechanisms And Organic Aerosol, Nga Lee Ng, Steven S. Brown, Alexander T. Archibald, Elliot Atlas, Ronald C. Cohen, John N. Crowley, Douglas A. Day, Neil M. Donahue, Juliane L. Fry, Hendrik Fuchs, Robert J. Griffin, Marcelo I. Guzman, Hartmut Hermann, Alma Hodzic, Yoshiteru Iinuma, José L. Jimenez, Astrid Kiendler-Scharr, Ben H. Lee, Deborah J. Luecken, Jingqiu Mao, Robert Mclaren, Anke Mutzel, Hans D. Osthoff, Bin Ouyang, Benedicte Picquet-Varrault, Ulrich Platt, Havala O. T. Pye, Yinon Rudich, Rebecca H. Schwantes, Manabu Shiraiwa, Jochen Stutz, Joel A. Thornton, Andreas Tilgner, Brent J. Williams, Rahul A. Zaveri
Chemistry Faculty Publications
Oxidation of biogenic volatile organic compounds (BVOC) by the nitrate radical (NO3) represents one of the important interactions between anthropogenic emissions related to combustion and natural emissions from the biosphere. This interaction has been recognized for more than 3 decades, during which time a large body of research has emerged from laboratory, field, and modeling studies. NO3-BVOC reactions influence air quality, climate and visibility through regional and global budgets for reactive nitrogen (particularly organic nitrates), ozone, and organic aerosol. Despite its long history of research and the significance of this topic in atmospheric chemistry, a number …
Aqueous Photochemistry Of Glyoxylic Acid, Alexis J. Eugene, Sha-Sha Xia, Marcelo I. Guzman
Aqueous Photochemistry Of Glyoxylic Acid, Alexis J. Eugene, Sha-Sha Xia, Marcelo I. Guzman
Chemistry Faculty Publications
Aerosols affect climate change, the energy balance of the atmosphere, and public health due to their variable chemical composition, size, and shape. While the formation of secondary organic aerosols (SOA) from gas phase precursors is relatively well understood, studying aqueous chemical reactions contributing to the total SOA budget is the current focus of major attention. Field measurements have revealed that mono-, di-, and oxo-carboxylic acids are abundant species present in SOA and atmospheric waters. This work explores the fate of one of these 2-oxocarboxylic acids, glyoxylic acid, which can photogenerate reactive species under solar irradiation. Additionally, the dark thermal aging …
Photocatalytic Reduction Of Fumarate To Succinate On Zns Mineral Surfaces, Ruixin Zhou, Marcelo I. Guzman
Photocatalytic Reduction Of Fumarate To Succinate On Zns Mineral Surfaces, Ruixin Zhou, Marcelo I. Guzman
Chemistry Faculty Publications
The reductive tricarboxylic acid (rTCA) cycle is an important central biosynthetic pathway that fixes CO2 into carboxylic acids. Among the five reductive steps in the rTCA cycle, the two-electron reduction of fumarate to succinate proceeds nonenzymatically on the surface of photoexcited sphalerite (ZnS) colloids suspended in water. This model reaction is chosen to systematically study the surface photoprocess occurring on ZnS in the presence of [Na2S] (1–10 mM) hole scavenger at 15 °C. Experiments at variable pH (5–10) indicate that monodissociated fumaric acid is the primary electron acceptor forming the monoprotic form of succinic acid. The following …
Heterogeneous Oxidation Of Catechol, Elizabeth A. Pillar, Ruixin Zhou, Marcelo I. Guzman
Heterogeneous Oxidation Of Catechol, Elizabeth A. Pillar, Ruixin Zhou, Marcelo I. Guzman
Chemistry Faculty Publications
Natural and anthropogenic emissions of aromatic hydrocarbons from biomass burning, agro-industrial settings, and fossil fuel combustion contribute precursors to secondary aerosol formation (SOA). How these compounds are processed under humid tropospheric conditions is the focus of current attention to understand their environmental fate. This work shows how catechol thin films, a model for oxygenated aromatic hydrocarbons present in biomass burning and combustion aerosols, undergo heterogeneous oxidation at the air–solid interface under variable relative humidity (RH = 0–90%). The maximum reactive uptake coefficient of O3(g) by catechol γO3 = (7.49 ± 0.35) × 10–6 occurs for …
Catechol Oxidation By Ozone And Hydroxyl Radicals At The Air-Water Interface, Elizabeth A. Pillar, Robert C. Camm, Marcelo I. Guzman
Catechol Oxidation By Ozone And Hydroxyl Radicals At The Air-Water Interface, Elizabeth A. Pillar, Robert C. Camm, Marcelo I. Guzman
Chemistry Faculty Publications
Anthropogenic emissions of aromatic hydrocarbons promptly react with hydroxyl radicals undergoing oxidation to form phenols and polyphenols (e.g., catechol) typically identified in the complex mixture of humic-like substances (HULIS). Because further processing of polyphenols in secondary organic aerosols (SOA) can continue mediated by a mechanism of ozonolysis at interfaces, a better understanding about how these reactions proceed at the air–water interface is needed. This work shows how catechol, a molecular probe of the oxygenated aromatic hydrocarbons present in SOA, can contribute interfacial reactive species that enhance the production of HULIS under atmospheric conditions. Reactive semiquinone radicals are quickly produced upon …
Interactive Comment On “Iodine Oxide In The Global Marine Boundary Layer” By C. Prados-Roman Et Al., Marcelo I. Guzman
Interactive Comment On “Iodine Oxide In The Global Marine Boundary Layer” By C. Prados-Roman Et Al., Marcelo I. Guzman
Chemistry Faculty Publications
No abstract provided.
Co2 Reduction Under Periodic Illumination Of Zns, Ruixin Zhou, Marcelo I. Guzman
Co2 Reduction Under Periodic Illumination Of Zns, Ruixin Zhou, Marcelo I. Guzman
Chemistry Faculty Publications
The photoreduction of CO2 to formate (HCOO–) in sphalerite (ZnS) aqueous suspensions is systematically studied in the presence of Na2S hole scavenger. A series of cut-on filters at λcut-on ≥ 280, 295, 305, 320, and 400 nm are used to measure the reaction rate of formate production. The dependence of the measured reaction rates on λcut-on indicates that a wavelength of λ = 345 nm is associated with the actual bandgap of the semiconductor nanocrystallites suspended in water. The results from apparent quantum yield measurements during periodic illumination experiments suggest that (1) valence-band …
Conversion Of Iodide To Hypoiodous Acid And Iodine In Aqueous Microdroplets Exposed To Ozone, Elizabeth A. Pillar, Marcelo I. Guzman, Jose M. Rodriguez
Conversion Of Iodide To Hypoiodous Acid And Iodine In Aqueous Microdroplets Exposed To Ozone, Elizabeth A. Pillar, Marcelo I. Guzman, Jose M. Rodriguez
Chemistry Faculty Publications
Halides are incorporated into aerosol sea spray, where they start the catalytic destruction of ozone (O3) over the oceans and affect the global troposphere. Two intriguing environmental problems undergoing continuous research are (1) to understand how reactive gas phase molecular halogens are directly produced from inorganic halides exposed to O3 and (2) to constrain the environmental factors that control this interfacial process. This paper presents a laboratory study of the reaction of O3 at variable iodide (I–) concentration (0.010–100 μM) for solutions aerosolized at 25 °C, which reveal remarkable differences in the reaction intermediates …
Organics In Environmental Ices: Sources, Chemistry, And Impacts, V. F. Mcneill, A. M. Grannas, J. P. D. Abbatt, M. Ammann, P. Ariya, T. Bartels-Rausch, F. Domine, D. J. Donaldson, Marcelo I. Guzman, D. Heger, T. F. Kahan, P. Klán, S. Masclin, C. Toubin, D. Voisin
Organics In Environmental Ices: Sources, Chemistry, And Impacts, V. F. Mcneill, A. M. Grannas, J. P. D. Abbatt, M. Ammann, P. Ariya, T. Bartels-Rausch, F. Domine, D. J. Donaldson, Marcelo I. Guzman, D. Heger, T. F. Kahan, P. Klán, S. Masclin, C. Toubin, D. Voisin
Chemistry Faculty Publications
The physical, chemical, and biological processes involving organics in ice in the environment impact a number of atmospheric and biogeochemical cycles. Organic material in snow or ice may be biological in origin, deposited from aerosols or atmospheric gases, or formed chemically in situ. In this manuscript, we review the current state of knowledge regarding the sources, properties, and chemistry of organic materials in environmental ices. Several outstanding questions remain to be resolved and fundamental data gathered before an accurate model of transformations and transport of organic species in the cryosphere will be possible. For example, more information is needed regarding …
Concentration Effects And Ion Properties Controlling The Fractionation Of Halides During Aerosol Formation, Marcelo I. Guzman, Richa R. Athalye, Jose M. Rodriguez
Concentration Effects And Ion Properties Controlling The Fractionation Of Halides During Aerosol Formation, Marcelo I. Guzman, Richa R. Athalye, Jose M. Rodriguez
Chemistry Faculty Publications
During the aerosolization process at the sea surface, halides are incorporated into aerosol droplets, where they may play an important role in tropospheric ozone chemistry. Although this process may significantly contribute to the formation of reactive gas phase molecular halogens, little is known about the environmental factors that control how halides selectively accumulate at the air-water interface. In this study, the production of sea spray aerosol is simulated using electrospray ionization (ESI) of 100 nM equimolar solutions of NaCl, NaBr, NaI, NaNO(2), NaNO(3), NaClO(4), and NaIO(4). The microdroplets generated are analyzed by mass spectrometry to study the comparative enrichment of …