scholarly journals Contribution of gaseous and particulate species to droplet solute composition at the Puy de Dôme, France

2003 ◽  
Vol 3 (5) ◽  
pp. 1509-1522 ◽  
Author(s):  
K. Sellegri ◽  
P. Laj ◽  
A. Marinoni ◽  
R. Dupuy ◽  
M. Legrand ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Removal Rate ◽  
Chemical Species ◽  
Solute Concentration ◽  
Complex Nature ◽  
Gaseous Species ◽  
Phase Partitioning ◽  
Gas Phases ◽  
Set Up

Abstract. Chemical reactions of dissolved gases in the liquid phase play a key role in atmospheric processes both in the formation of secondary atmospheric compounds and their wet removal rate but also in the regulation of the oxidizing capacity of the troposphere. The behavior of gaseous species and their chemical transformation in clouds are difficult to observe experimentally given the complex nature of clouds. During a winter field campaign at the summit of the Puy de Dôme (central France, 1465 m a.s.l), we have deployed an experimental set-up to provide a quantification of phase partitioning of both organic (CH3COOH, HCOOH, H2C2O4) and inorganic (NH3, HNO3, SO2, HCl) species in clouds. We found that nitric and hydrochloric acids can be considered close to Henry's law equilibrium, within analytical uncertainty and instrumental errors. On another hand, for NH3 and carboxylic acids, dissolution of material from the gas phase is kinetically limited and never reaches the equilibrium predicted by thermodynamics, resulting in significant sub-saturation of the liquid phase. On the contrary, SIV is supersaturated in the liquid phase, in addition to the presence of significant aerosol-derived SVI transferred through nucleation scavenging. Upon droplet evaporation, a significant part of most species, including SIV, tends to efficiently return back into the gas phase. Overall, gas contribution to the droplet solute concentration ranges from at least 48.5 to 98% depending on the chemical species. This is particularly important considering that aerosol scavenging efficiencies are often calculated assuming a negligible gas-phase contribution to the solute concentration. Our study emphasizes the need to account for the in-cloud interaction between particles and gases to provide an adequate modeling of multiphase chemistry systems and its impact on the atmospheric aerosol and gas phases.

scholarly journals Contribution of gaseous and particulate species to droplet solute composition

2003 ◽  
Vol 3 (1) ◽  
pp. 479-519 ◽  
Author(s):  
K. Sellegri ◽  
P. Laj ◽  
A. Marinoni ◽  
R. Dupuy ◽  
M. Legrand ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Carboxylic Acids ◽  
Chemical Transformation ◽  
Removal Rate ◽  
Multiphase System ◽  
Complex Nature ◽  
Gaseous Species ◽  
Phase Partitioning ◽  
Hygroscopic Properties

Abstract. Chemical reactions of dissolved gases in the liquid phase play a key role in atmospheric processes both in the formation of secondary atmospheric compounds and their wet removal rate but also in the regulation of the oxidizing capacity of the troposphere (Lelieveld and Crutzen, 1991). The behaviour of gaseous species and their chemical transformation in clouds are difficult to observe experimentally given the complex nature of clouds. In this study, we have deployed an experimental set-up to provide an in-situ quantification of phase partitioning and chemical transformation of both organic (CH3COOH, HCOOH, H2C2O4) and inorganic (NH3, HNO3, SO2, HCl) species in clouds. We found that, carboxylic acids, nitrate, and chloride can be considered close to Henry's law equilibrium, within analytical uncertainty and instrumental errors. On another hand, for reduced nitrogen species, dissolution of material from the gas phase is kinetically limited and never reaches the equilibrium predicted by thermodynamics, resulting in significant sub-saturation of the liquid phase. On the contrary, sulfate is supersaturated in the liquid phase, indicating the presence of significant aerosol-derived material transferred through nucleation scavenging. Upon droplet evaporation, most species, including SO2, tend to efficiently return back into the gas phase. In that sense, these species contribute to acidification (for carboxylic acids) or neutralization (for NH3) of the liquid-phase but not totally of the processed aerosols. The only species that appears to be modified in the multiphase system is nitrate. A fraction of at least 10 to 40% of the liquid phase NO3 originates from dissolved HNO3 of which only a fraction evaporates back to the gas phase upon evaporation, resulting in an NO3 enrichment of the aerosol phase. In-cloud gas-to-particle transfer of HNO3 possibly plays a key role in aerosol acidification and in the modification of their hygroscopic properties. Our study emphasizes the need to account for the in-cloud interaction between particles and gases to provide an adequate modeling of multiphase chemistry systems and its impact on the atmospheric aerosol and gas phases.

CONDITIONS FOR THE PHOTOCHEMICAL NITRATION OF BENZENE

1965 ◽  
Vol 43 (6) ◽  
pp. 1714-1719 ◽  
Author(s):  
David L. Bunbury
Keyword(s):  
Liquid Phase ◽  
Quantum Yield ◽  
Nitrogen Dioxide ◽  
Gas Phase ◽  
Dark Reaction ◽  
Gas Phases

The reaction of benzene and nitrogen dioxide to produce nitrobenzene has been studied in the liquid and gas phases, in the dark, and with irradiation by light of 439 mμ and of 366 mμ. The concentration of NO2 in the liquid was varied from 0.08 to 1.6 moles/1 and in the gas from 0.0035 to 0.053 moles/1. No nitrobenzene was produced under any conditions in the liquid phase. Nitrobenzene is produced in the gas phase at high NO2 concentrations with irradiation by 366 mμ light. The quantum yield is 0.2. At 439 mμ the quantum yield is not more than 0.02. There is a very small dark reaction. As the concentration of NO2 in the gas is reduced the yield of nitrobenzene falls off very rapidly and is zero at the lowest concentration used, both in dark and light.

THE RADIOLYSIS OF ETHANOL: IV. DEUTERATED ETHANOLS IN THE LIQUID AND GAS PHASES

1965 ◽  
Vol 43 (5) ◽  
pp. 1484-1492 ◽  
Author(s):  
J. J. J. Myron ◽  
G. R. Freeman
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Vapor Phase ◽  
Isotope Effects ◽  
Methane Formation ◽  
Gas Phases ◽  
Product Distributions ◽  
Γ Rays ◽  
The Difference ◽  
Α Particles

The value of G(–ethanol) in the vapor phase is nearly double that in the liquid phase. Part of the difference appears to be due to the recombination of radicals in liquid cages. Ethanol molecules, on the average, break into smaller fragments in the gas than in the liquid phase radiolysis. The isotopic compositions of the hydrogen produced from various deuterated ethanols are consistent with the suggestion that the reaction[Formula: see text]occurs to a significant extent in the liquid but not in the gas phase. This reaction probably involves the shift of a hydrogen atom along a hydrogen bond. The reaction[Formula: see text]does not occur to an appreciable extent in the liquid phase. In the liquid phase the relative contributions of the three different groups in the ethanol molecule to hydrogen production are in the order [Formula: see text] A similar trend occurs in the gas, although the contributions of the three groups are more nearly equal in this phase. Isotope effects, in the range kH/kD = 2.2–3.9 per bond, occur in the methane formation mechanism. The isotope effects are somewhat smaller in the liquid than in the vapor phase and somewhat smaller in the inhibited than in the uninhibited systems. A comparison of product distributions in the liquid and gas radiolyses of several compounds by γ-rays and by α-particles indicates that L.E.T. effects can also occur in the gas phase.

New MESSy scavenging subroutine to treat aerosol particles gas-phase partitioning in convective clouds

2021 ◽  
Author(s):  
Giorgio Taverna ◽  
Marc Barra ◽  
Holger Tost
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Aerosol Particles ◽  
Phase Partitioning ◽  
Convective Clouds ◽  
Terrestrial Atmosphere ◽  
Deep Convective Clouds ◽  
High Level

<p>The Modular Earth Submodel System (MESSy) has been proven to be successful in the understanding of several processes which characterize the terrestrial atmosphere and climate.</p><p>However, the complexity of aerosol particles/gas phase partitioning of species in deep convective clouds together with the inherent problems of modelling sub-grid scale processes, make MESSy results significant underestimated, especially in case of SO<sub>2</sub>, when compared with available flight observations. For this reason, the subroutine which reproduce the scavenging of these species has been updated to include a more realistic treatment of liquid/phase partitioning of aerosol induced species in high level clouds.</p><p>Results obtained are shown in this poster.</p>

scholarly journals Regularized machine learning on molecular graph model explains systematic error in DFT enthalpies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Himaghna Bhattacharjee ◽  
Nikolaos Anesiadis ◽  
Dionisios G. Vlachos
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Statistical Tests ◽  
Molecular Graph ◽  
Chemical Species ◽  
Graph Model ◽  
Basis Set ◽  
Gaseous Species ◽  
Elementary Reactions ◽  
Gas Phase Molecules

AbstractA major goal of materials research is the discovery of novel and efficient heterogeneous catalysts for various chemical processes. In such studies, the candidate catalyst material is modeled using tens to thousands of chemical species and elementary reactions. Density Functional Theory (DFT) is widely used to calculate the thermochemistry of these species which might be surface species or gas-phase molecules. The use of an approximate exchange correlation functional in the DFT framework introduces an important source of error in such models. This is especially true in the calculation of gas phase molecules whose thermochemistry is calculated using the same planewave basis set as the rest of the surface mechanism. Unfortunately, the nature and magnitude of these errors is unknown for most practical molecules. Here, we investigate the error in the enthalpy of formation for 1676 gaseous species using two different DFT levels of theory and the ‘ground truth values’ obtained from the NIST database. We featurize molecules using graph theory. We use a regularized algorithm to discover a sparse model of the error and identify important molecular fragments that drive this error. The model is robust to rigorous statistical tests and is used to correct DFT thermochemistry, achieving more than an order of magnitude improvement.

Monitoring of oxygen in the gas and liquide phases of bottles of wine at bottling and during storage

OENO One ◽  
2006 ◽  
Vol 40 (1) ◽  
pp. 35 ◽  
Author(s):  
Jean-Claude Vidal ◽  
Michel Moutounet
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Operating Conditions ◽  
Partial Pressure Of Oxygen ◽  
Total Oxygen ◽  
Gas Phases ◽  
Exchange Kinetics ◽  
Two Phases ◽  
Gas Exchange Kinetics ◽  
Kinetics Of

<p style="text-align: justify;">The assaying of oxygen in the headspace of a bottle combined with that of dissolved oxygen in the wine makes it possible to obtain the total oxygen per bottle. The first analyses performed at bottling show that 0.38 to 3.58 mg oxygen per bottle is trapped in the headspace. Operating conditions account for these substantial variations. Monitoring the oxygen contents in the liquid and gas phases of three batches of wine over a period of several months and the analysis of old bottles show that the headspace functions as an oxygen reserve for the wine, that is to say that as the wine uses oxygen, there is passage of the gas from the headspace to the wine. This is related to a movement towards a balance between the two phases as the partial pressure of oxygen in the gas phase is always greater than that of the liquid phase. Finally, this gas exchange kinetics within the bottle outweighs the kinetics of penetration of the bottle by oxygen in the external atmosphere, at least while the total oxygen trapped at bottling has not been used up.</p>

Application of Disk Aerators to Recarbonation of Alkaline Wastewater from Wet Gasification of Carbide

1991 ◽  
Vol 24 (7) ◽  
pp. 277-284 ◽  
Author(s):  
E. Gomólka ◽  
B. Gomólka
Keyword(s):  
Carbon Dioxide ◽  
Liquid Phase ◽  
Gas Phase ◽  
Flue Gas ◽  
Carbonic Acid ◽  
Low Cost ◽  
Flue Gases ◽  
Carbon Dioxide Content ◽  
Patent Claim ◽  
Phase Dispersion

Whenever possible, neutralization of alkaline wastewater should involve low-cost acid. It is conventional to make use of carbonic acid produced via the reaction of carbon dioxide (contained in flue gases) with water according to the following equation: Carbon dioxide content in the flue gas stream varies from 10% to 15%. The flue gas stream may either be passed to the wastewater contained in the recarbonizers, or. enter the scrubbers (which are continually sprayed with wastewater) from the bottom in oountercurrent. The reactors, in which recarbonation occurs, have the ability to expand the contact surface between gaseous and liquid phase. This can be achieved by gas phase dispersion in the liquid phase (bubbling), by liquid phase dispersion in the gas phase (spraying), or by bubbling and spraying, and mixing. These concurrent operations are carried out during motion of the disk aerator (which is a patent claim). The authors describe the functioning of the disk aerator, the composition of the wastewater produced during wet gasification of carbide, the chemistry of recarbonation and decarbonation, and the concept of applying the disk aerator so as to make the wastewater fit for reuse (after suitable neutralization) as feeding water in acetylene generators.

Modeling of aerated upflow fixed bed reactors for nitrification

1999 ◽  
Vol 39 (4) ◽  
pp. 85-92 ◽  
Author(s):  
J. Behrendt
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Liquid Phase ◽  
Gas Phase ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Bulk Liquid ◽  
Initial Value ◽  
Fixed Bed Reactors ◽  
Number Of Cells

A mathematical model for nitrification in an aerated fixed bed reactor has been developed. This model is based on material balances in the bulk liquid, gas phase and in the biofilm area. The fixed bed is divided into a number of cells according to the reduced remixing behaviour. A fixed bed cell consists of 4 compartments: the support, the gas phase, the bulk liquid phase and the stagnant volume containing the biofilm. In the stagnant volume the biological transmutation of the ammonia is located. The transport phenomena are modelled with mass transfer formulations so that the balances could be formulated as an initial value problem. The results of the simulation and experiments are compared.

Theoretical analysis of counter-current absorption of a poorly soluble gas based on the PDE-AD model

1986 ◽  
Vol 51 (6) ◽  
pp. 1222-1239 ◽  
Author(s):  
Pavel Moravec ◽  
Vladimír Staněk
Keyword(s):  
Experimental Data ◽  
Liquid Phase ◽  
Gas Phase ◽  
Transfer Functions ◽  
Packed Bed ◽  
Packed Bed Column ◽  
Interfacial Transport ◽  
Gaseous Component ◽  
Poorly Soluble ◽  
Counter Current

Expression have been derived in the paper for all four possible transfer functions between the inlet and the outlet gas and liquid steams under the counter-current absorption of a poorly soluble gas in a packed bed column. The transfer functions have been derived for the axially dispersed model with stagnant zone in the liquid phase and the axially dispersed model for the gas phase with interfacial transport of a gaseous component (PDE - AD). calculations with practical values of parameters suggest that only two of these transfer functions are applicable for experimental data evaluation.

Reesterification of ethyl acetate by propanol catalysed by glycidyl methacrylate copolymers containing sulphonic acid groups

1981 ◽  
Vol 46 (8) ◽  
pp. 1941-1946 ◽  
Author(s):  
Karel Setínek
Keyword(s):  
Liquid Phase ◽  
Ethyl Acetate ◽  
Kinetic Study ◽  
Gas Phase ◽  
Nonlinear Regression ◽  
Kinetic Data ◽  
Glycidyl Methacrylate ◽  
Kinetic Equations ◽  
Methacrylate Copolymers ◽  
Styrene Divinylbenzene

A series of differently crosslinked macroporous 2,3-epoxypropyl methacrylate-ethylenedimethacrylate copolymers with chemically bonded propylsulphonic acid groups were used as catalysts for the kinetic study of reesterification of ethyl acetate by n-propanol in the liquid phase at 52 °C and in the gas phase at 90 °C. Analysis of kinetic data by the method of nonlinear regression for a series of equations of the Langmuir-Hinshelwood type showed that kinetic equations which describe best the course of the reaction are the same as for the earlier studied sulphonated macroporous styrene-divinylbenzene copolymers. Compared types of catalysts differ, however, in the dependence of their activity on the degree of crosslinking of the copolymer used.

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