scholarly journals Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006

2009 ◽  
Vol 9 (6) ◽  
pp. 2141-2156 ◽  
Author(s):  
C. Fountoukis ◽  
A. Nenes ◽  
A. Sullivan ◽  
R. Weber ◽  
T. Van Reken ◽  
...  
Keyword(s):  
Gas Phase ◽  
Mexico City ◽  
Thermodynamic Equilibrium ◽  
Phase State ◽  
Early Morning ◽  
Molar Ratio ◽  
Aerosol Composition ◽  
Inorganic Species ◽  
Thermodynamic Equilibrium Model

Abstract. Fast measurements of aerosol and gas-phase constituents coupled with the ISORROPIA-II thermodynamic equilibrium model are used to study the partitioning of semivolatile inorganic species and phase state of Mexico City aerosol sampled at the T1 site during the MILAGRO 2006 campaign. Overall, predicted semivolatile partitioning agrees well with measurements. PM2.5 is insensitive to changes in ammonia but is to acidic semivolatile species. For particle sizes up to 1μm diameter, semi-volatile partitioning requires 15–30 min to equilibrate; longer time is typically required during the night and early morning hours. Aerosol and gas-phase speciation always exhibits substantial temporal variability, so that aerosol composition measurements (bulk or size-resolved) obtained over large integration periods are not reflective of its true state. When the aerosol sulfate-to-nitrate molar ratio is less than unity, predictions improve substantially if the aerosol is assumed to follow the deliquescent phase diagram. Treating crustal species as "equivalent sodium" (rather than explicitly) in the thermodynamic equilibrium calculations introduces important biases in predicted aerosol water uptake, nitrate and ammonium; neglecting crustals further increases errors dramatically. This suggests that explicitly considering crustals in the thermodynamic calculations is required to accurately predict the partitioning and phase state of aerosols.

scholarly journals Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006

2007 ◽  
Vol 7 (3) ◽  
pp. 9203-9233 ◽  
Author(s):  
C. Fountoukis ◽  
A. Nenes ◽  
A. Sullivan ◽  
R. Weber ◽  
T. VanReken ◽  
...  
Keyword(s):  
Gas Phase ◽  
Mexico City ◽  
Thermodynamic Equilibrium ◽  
Phase State ◽  
Molar Ratio ◽  
Inorganic Species ◽  
Equilibrium Calculations ◽  
Thermodynamic Equilibrium Model ◽  
Thermodynamic Equilibrium Calculations

Abstract. Fast measurements of aerosol and gas-phase constituents coupled with the ISORROPIA-II thermodynamic equilibrium model are used to study the partitioning of semivolatile inorganic species and phase state of Mexico City aerosol sampled at the T1 site during the MILAGRO 2006 campaign. Overall, predicted semivolatile partitioning agrees well with measurements. PM2.5 is insensitive to changes in ammonia but is to acidic semivolatile species. Semi-volatile partitioning equilibrates on a timescale between 6 and 20 min. When the aerosol sulfate-to-nitrate molar ratio is less than 1, predictions improve substantially if the aerosol is assumed to follow the deliquescent phase diagram. Treating crustal species as "equivalent sodium" (rather than explicitly) in the thermodynamic equilibrium calculations introduces important biases in predicted aerosol water uptake, nitrate and ammonium; neglecting crustals further increases errors dramatically. This suggests that explicitly considering crustals in the thermodynamic calculations are required to accurately predict the partitioning and phase state of aerosols.

Production, Injection and Flow of Petroleum with High Levels of CO2: Operational and Flow Assurance Aspects

2016 ◽  
Vol 830 ◽  
pp. 78-84
Author(s):  
Ivanilto Andreolli ◽  
Luciene de Arruda Bernardo
Keyword(s):  
Gas Phase ◽  
Molar Ratio ◽  
Flow Assurance ◽  
Daily Production ◽  
Treatment And Disposal ◽  
Export System ◽  
Theoretical Analyses ◽  
Concentration Levels ◽  
Operational Aspects

Petroleum production always comes accompanied by some contaminants, including CO2. Recent pre-salt exploration in Brazil indicates significant carbon dioxide (CO2) concentration levels. Whereas in post-salt areas a ratio of 1 to 2% in CO2 concentration was observed, in the pre-salt area this molar ratio increased to 15 to 20% in relation to the gas phase, and were even higher in some cases. Several challenges have emerged in the production, treatment and disposal of oil with such high levels of CO2. The aim of this study is to show the management of CO2 in a pre-salt producing platform whose CO2 content is about 18% molar in the gas phase. The focus is on the operational aspects of daily production, where theoretical analyses are compared with the data observed in the field. Scenarios of production, injection, treatment and export are presented with emphasis on the aspects of flow assurance, the characterization of fluids, the integration of the injection-production-export system, and the dilution of CO2.

scholarly journals Implementation of a Markov Chain Monte Carlo Method to inorganic aerosol modeling of observations from the MCMA-2003 Campaign. Part II: Model application to the CENICA, Pedregal and Santa Ana sites

2006 ◽  
Vol 6 (4) ◽  
pp. 5999-6040
Author(s):  
F. M. San Martini ◽  
E. J. Dunlea ◽  
R. Volkamer ◽  
T. B. Onasch ◽  
J. T. Jayne ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Markov Chain ◽  
Markov Chain Monte Carlo ◽  
Nitric Acid ◽  
Gas Phase ◽  
Mexico City ◽  
Monte Carlo Model ◽  
Rural Site ◽  
Inorganic Species ◽  
Inorganic Aerosol

Abstract. A Markov Chain Monte Carlo model for integrating the observations of inorganic species with a thermodynamic equilibrium model was presented in Part I of this series. Using observations taken at three ground sites, i.e. a residential, industrial and rural site, during the MCMA-2003 campaign in Mexico City, the model is used to analyze the inorganic aerosol and ammonia data and predict gas phase concentrations of nitric and hydrochloric acid. In general the model is able to accurately predict the observed inorganic aerosol concentrations at all three sites. The agreement between the predicted and observed gas phase ammonia concentration is excellent. The NOz concentration calculated from the NOy, NO and NO2 observations is of limited use in constraining the gas phase nitric acid concentration given the large uncertainties in this measure of nitric acid and additional reactive nitrogen species. Focusing on the acidic period of 9–11 April identified by Salcedo et al. (2006), the model accurately predicts the aerosol phase observations during this period with the exception of the nitrate predictions after 10:00 a.m. (CDT) on 9 April, where the model underpredicts the observations by, on average, 20%. For periods when the aerosol chloride observations are consistently above the detection limit, the model is able to both accurately predict the aerosol chloride predictions and provide well-constrained HCl (g) concentrations. When the aerosols are aqueous, the most likely concentrations of HCl (g) are in the sub-ppbv range. The most likely predicted concentration of HCl (g) was found to reach concentrations of order 10 ppbv if the aerosols are dry. Finally, the atmospheric relevance of HCl (g) is discussed in terms of its indicator properties for the possible influence of chlorine-mediated photochemistry in Mexico City.

scholarly journals Implementation of a Markov Chain Monte Carlo method to inorganic aerosol modeling of observations from the MCMA-2003 campaign – Part II: Model application to the CENICA, Pedregal and Santa Ana sites

2006 ◽  
Vol 6 (12) ◽  
pp. 4889-4904 ◽  
Author(s):  
F. M. San Martini ◽  
E. J. Dunlea ◽  
R. Volkamer ◽  
T. B. Onasch ◽  
J. T. Jayne ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Markov Chain ◽  
Markov Chain Monte Carlo ◽  
Nitric Acid ◽  
Gas Phase ◽  
Mexico City ◽  
Monte Carlo Model ◽  
Rural Site ◽  
Inorganic Particle ◽  
Inorganic Species

Abstract. A Markov Chain Monte Carlo model for integrating the observations of inorganic species with a thermodynamic equilibrium model was presented in Part I of this series. Using observations taken at three ground sites, i.e. a residential, industrial and rural site, during the MCMA-2003 campaign in Mexico City, the model is used to analyze the inorganic particle and ammonia data and to predict gas phase concentrations of nitric and hydrochloric acid. In general, the model is able to accurately predict the observed inorganic particle concentrations at all three sites. The agreement between the predicted and observed gas phase ammonia concentration is excellent. The NOz concentration calculated from the NOy, NO and NO2 observations is of limited use in constraining the gas phase nitric acid concentration given the large uncertainties in this measure of nitric acid and additional reactive nitrogen species. Focusing on the acidic period of 9–11 April identified by Salcedo et al. (2006), the model accurately predicts the particle phase observations during this period with the exception of the nitrate predictions after 10:00 a.m. (Central Daylight Time, CDT) on 9 April, where the model underpredicts the observations by, on average, 20%. This period had a low planetary boundary layer, very high particle concentrations, and higher than expected nitrogen dioxide concentrations. For periods when the particle chloride observations are consistently above the detection limit, the model is able to both accurately predict the particle chloride mass concentrations and provide well-constrained HCl (g) concentrations. The availability of gas-phase ammonia observations helps constrain the predicted HCl (g) concentrations. When the particles are aqueous, the most likely concentrations of HCl (g) are in the sub-ppbv range. The most likely predicted concentration of HCl (g) was found to reach concentrations of order 10 ppbv if the particles are dry. Finally, the atmospheric relevance of HCl (g) is discussed in terms of its indicator properties for the possible influence of chlorine-mediated photochemistry in Mexico City.

scholarly journals Aerosol composition and the contribution of SOA formation over Mediterranean forests

2018 ◽  
Vol 18 (10) ◽  
pp. 7041-7056 ◽  
Author(s):  
Evelyn Freney ◽  
Karine Sellegri ◽  
Mounir Chrit ◽  
Kouji Adachi ◽  
Joel Brito ◽  
...  
Keyword(s):  
Gas Phase ◽  
Mass Spectrometer ◽  
Organic Aerosol ◽  
Proton Transfer Reaction ◽  
Oxidation Products ◽  
Mediterranean Forests ◽  
Aerosol Composition ◽  
Total Contribution ◽  
Inorganic Species ◽  
Forested Areas

Abstract. As part of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx), a series of aerosol and gas-phase measurements were deployed aboard the SAFIRE ATR42 research aircraft in summer 2014. The present study focuses on the four flights performed in late June early July over two forested regions in the south of France. We combine in situ observations and model simulations to aid in the understanding of secondary organic aerosol (SOA) formation over these forested areas in the Mediterranean and to highlight the role of different gas-phase precursors. The non-refractory particulate species measured by a compact aerosol time-of-flight mass spectrometer (cToF-AMS) were dominated by organics (60 to 72 %) followed by a combined contribution of 25 % by ammonia and sulfate aerosols. The contribution from nitrate and black carbon (BC) particles was less than 5 % of the total PM1 mass concentration. Measurements of non-refractory species from off-line transmission electron microscopy (TEM) showed that particles have different mixing states and that large fractions (35 %) of the measured particles were organic aerosol containing C, O, and S but without inclusions of crystalline sulfate particles. The organic aerosol measured using the cToF-AMS contained only evidence of oxidized organic aerosol (OOA), without a contribution of fresh primary organic aerosol. Positive matrix factorization (PMF) on the combined organic–inorganic matrices separated the oxidized organic aerosol into a more-oxidized organic aerosol (MOOA), and a less-oxidized organic aerosol (LOOA). The MOOA component is associated with inorganic species and had higher contributions of m∕z 44 than the LOOA factor. The LOOA factor is not associated with inorganic species and correlates well with biogenic volatile organic species measured with a proton-transfer-reaction mass spectrometer, such as isoprene and its oxidation products (methyl vinyl ketone, MVK; methacroleine, MACR; and isoprene hydroxyhydroperoxides, ISOPOOH). Despite a significantly high mixing ratio of isoprene (0.4 to 1.2 ppbV) and its oxidation products (0.2 and 0.8 ppbV), the contribution of specific signatures for isoprene epoxydiols SOA (IEPOX-SOA) within the aerosol organic mass spectrum (m∕z 53 and m∕z 82) were very weak, suggesting that the presence of isoprene-derived SOA was either too low to be detected by the cToF-AMS, or that SOA was not formed through IEPOX. This was corroborated through simulations performed with the Polyphemus model showing that although 60 to 80 % of SOA originated from biogenic precursors, only about 15 to 32 % was related to isoprene (non-IEPOX) SOA; the remainder was 10 % sesquiterpene SOA and 35 to 40 % monoterpene SOA. The model results show that despite the zone of sampling being far from industrial or urban sources, a total contribution of 20 to 34 % of the SOA was attributed to purely anthropogenic precursors (aromatics and intermediate or semi-volatile compounds). The measurements obtained during this study allow us to evaluate how biogenic emissions contribute to increasing SOA concentrations over Mediterranean forested areas. Directly comparing these measurements with the Polyphemus model provides insight into the SOA formation pathways that are prevailing in these forested areas as well as processes that need to be implemented in future simulations.

scholarly journals Aerosol composition and the contribution of SOA formation over Mediterranean forests

2017 ◽  
Author(s):  
Evelyn Freney ◽  
Karine Sellegri ◽  
Mounir Chrit ◽  
Kouji Adachi ◽  
Joel Brito ◽  
...  
Keyword(s):  
Gas Phase ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Dust Particles ◽  
Large Contribution ◽  
Mediterranean Forests ◽  
Aerosol Composition ◽  
Tem Analysis ◽  
Organic Species ◽  
Inorganic Species

Abstract. As part of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx), a series of aerosol and gas phase measurements were deployed aboard the SAFIRE ATR-42 research aircraft in summer 2014. The present study focuses on the 4 flights performed in late June early July over two forested regions in the south of France. We combine in situ observations and model simulations to aid in the understanding of secondary organic aerosol (SOA) formation over these forested areas in the Mediterranean and to highlight the role of different gas-phase precursors. The non-refractory particulate species measured by C-ToF-AMS instrument were dominated by organic species (60 to 72 %) followed by a combined contribution of 25 % by ammonia and sulphate aerosols. The contribution from the anthropogenic nitrate and black carbon (BC) concentrations, measured by an SP2, never contributed to more than 5 % each to the total PM1 mass concentration. Measurements of non-refractory species from off-line transmission electron microscopy (TEM) were coherent with the C-ToF-AMS instrument, showing a large contribution of externally mixed organic aerosol and externally mixed sulphate particles. Externally mixed organic aerosols, were equally identified with S signals, which may suggest the presence of organo-sulphates. Measurements of refractory species from TEM analysis showed a significant contribution of both sea salt and dust particles depending on the air mass trajectory. The organic aerosol measured by the C-ToF-AMS contained only evidence of oxidised organic aerosol (OOA), without a contribution of fresh primary organic aerosol. Positive matrix factorization (PMF) on the combined organic/inorganic matrices separated the oxidised organic aerosol into a more oxidised organic aerosol (MOOA), and a less oxidised organic aerosol (LOOA). The MOOA component is associated with inorganics species and had higher O : C ratios than the LOOA factor. The LOOA factor is not associated with inorganic species and correlates well with biogenic volatile organic species measured with a PTR-MS, such as isoprene and its oxidation products (methylvinylketone (MVK), methacroleine (MACR), and isoprene hydroxyhydroperoxides (ISOPOOH)). Despite a significantly high mixing ratio of isoprene (2– ppbV) and oxidation products (0.6 and 1.2 ppbV), the contribution of specific signatures for isoprene epoxydiols SOA (IEPOX) within the aerosol organic mass spectrum (m / z 53 and m / z 82) were very weak, suggesting that isoprene SOA may be formed through a non-IEPOX route here, or with different precursors without clear mass spectral signatures in the C-ToF-AMS. This was corroborated through simulations performed with the Polyphemus model showing that 60 to 80 % of SOA originated from biogenic precursors: about 15 to 32 % isoprene (non-IEPOX) SOA, 10 % sesquiterpenes SOA and 35 to 40 % monoterpenes SOA). A total of 20 to 34 % was attributed to purely anthropogenic precursors (aromatics and intermediate/semi volatile compounds).

scholarly journals Predicting diurnal variability of fine inorganic aerosols and their gas-phase precursors near downtown Mexico City

2007 ◽  
Vol 7 (4) ◽  
pp. 11257-11294 ◽  
Author(s):  
M. Moya ◽  
C. Fountoukis ◽  
A. Nenes ◽  
E. Matías ◽  
M. Grutter
Keyword(s):  
Gas Phase ◽  
Mexico City ◽  
Molar Ratio ◽  
Modeling Framework ◽  
Diurnal Variability ◽  
Inorganic Aerosols ◽  
Quality Modeling ◽  
Model Predictions ◽  
Daily Sampling ◽  
Particulate Ammonium

Abstract. Partitioning of semi-volatile nitrate and ammonium between the gas and particulate phases is studied combining two thermodynamic models that explicitly include crustal elements and simulate both branches (deliquescence, efflorescence) of aerosol behavior and measurements taken near downtown Mexico City during a field campaign conducted in February–March, 2005. Overall, no significant differences between model predictions (within 30% of error) are observed for particulate ammonium (PM2.5, PM1). In cases of moderate to high RH (40–70%), mostly occurring during the 1st and 2nd daily sampling periods (06:00–10:00 h, 10:00–14:00 h, LST), 4 h PM2.5 nitrate measurements are predicted within 30%. When RH drops below 30%, characteristic of the afternoon sampling periods (14:00-18:00 h), the efflorescence branch is most consistent with observed PM nitrate. Residual error analysis of these low RH cases suggest that aerosol nitrate loading or sulfate-to-nitrate molar ratio control phase behavior, hence the partitioning of semi-volatile PM2.5 nitrate in gas and particulate phases. Finally, inclusion of crustal elements in the modeling framework reduces the error in predicted PM2.5 ammonium by 25%. These findings, if generally applicable, can help improve air quality modeling in nitrate deficient environments.

scholarly journals Synthesis and Characterization of Partially Renewable Oleic Acid-Based Ionomers for Proton Exchange Membranes

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 130
Author(s):  
Carlos Corona-García ◽  
Alejandro Onchi ◽  
Arlette A. Santiago ◽  
Araceli Martínez ◽  
Daniella Esperanza Pacheco-Catalán ◽  
...  
Keyword(s):  
Oleic Acid ◽  
Proton Conductivity ◽  
Electrochemical Impedance ◽  
Proton Exchange Membranes ◽  
Proton Exchange ◽  
Molar Ratio ◽  
Aromatic Diamines ◽  
Chemical Structures ◽  
Long Chain

The future availability of synthetic polymers is compromised due to the continuous depletion of fossil reserves; thus, the quest for sustainable and eco-friendly specialty polymers is of the utmost importance to ensure our lifestyle. In this regard, this study reports on the use of oleic acid as a renewable source to develop new ionomers intended for proton exchange membranes. Firstly, the cross-metathesis of oleic acid was conducted to yield a renewable and unsaturated long-chain aliphatic dicarboxylic acid, which was further subjected to polycondensation reactions with two aromatic diamines, 4,4′-(hexafluoroisopropylidene)bis(p-phenyleneoxy)dianiline and 4,4′-diamino-2,2′-stilbenedisulfonic acid, as comonomers for the synthesis of a series of partially renewable aromatic-aliphatic polyamides with an increasing degree of sulfonation (DS). The polymer chemical structures were confirmed by Fourier transform infrared (FTIR) and nuclear magnetic resonance (1H, 13C, and 19F NMR) spectroscopy, which revealed that the DS was effectively tailored by adjusting the feed molar ratio of the diamines. Next, we performed a study involving the ion exchange capacity, the water uptake, and the proton conductivity in membranes prepared from these partially renewable long-chain polyamides, along with a thorough characterization of the thermomechanical and physical properties. The highest value of the proton conductivity determined by electrochemical impedance spectroscopy (EIS) was found to be 1.55 mS cm−1 at 30 °C after activation of the polymer membrane.

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