Adsorption of Atmospheric Gases at the Air−Water Interface. I. NH<sub>3</sub>

Donaldson, D. J.

doi:10.1021/jp9833247

Cited by 147 publications

(183 citation statements)

References 31 publications

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“…The optimized pre-exponential factors for R1 and R10 lie respectively slightly below and above the values obtained by Schoppelrei et al [22] (see Table 1). The activation energy for NH 3 (g) production from NH 4 + (reaction R2) is close to the barrier of 41 kJ.mol -1 reported by Donaldson [64]. Reaction R11 corresponds to the sum of reactions R11a, R11b and R11c presented in the literature review.…”

Section: Kinetic Modelingsupporting

confidence: 81%

Detailed modeling of the evaporation and thermal decomposition of urea‐water solution in SCR systems

2011

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This work aims to develop a multi-component evaporation model for droplets of urea-watersolution (UWS) and a thermal decomposition model of urea for automotive exhausts using the Selective Catalytic Reduction (SCR) systems. In the multi-component evaporation model, the influence of urea on the UWS evaporation is taken into account using a NRTL activity model. The thermal decomposition model is based on a semi-detailed kinetic scheme accounting not only for the production of ammonia (NH 3 ) and isocyanic acid (HNCO), but also for the formation of heavier solid by-products (biuret, cyanuric acid and ammelide). This kinetics model has been validated against gaseous data as well as solid-phase concentration profiles obtained by Lundstroem et al. (2009) andSchaber et al. (2004). Both models have been implemented in IFP-C3D industrial software in order to simulate UWS droplet evaporation and decomposition as well as the formation of solid by-products. It has been shown that the presence of the urea solute has a small influence on the water evaporation rate, but its effect on the UWS temperature is significant. In addition, the contributions of hydrolysis and thermolysis to urea decomposition have been assessed. Finally, the impacts of the heating rate as well as gas-phase chemistry on urea decomposition pathways have been studied in detail. It has been shown that reducing the heating rate of the UWS causes the extent of the polymerization to decrease because of the higher activation energy.

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Section: Kinetic Modelingsupporting

confidence: 81%

Detailed modeling of the evaporation and thermal decomposition of urea‐water solution in SCR systems

2011

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“…The direct proportionality between K sol,cc,Xi and α s,Xi , however, implies a gas phase composition dependence of the solubility, because α s,Xi decreases with increasing surface and gas phase concentration of all competitively co-adsorbing species. A comparable treatment of the equilibrium between gas, interface and bulk has also been presented by Donaldson (1999). This effect limits the applicability of solubilities or Henry's law coefficients determined for highly dilute solu-…”

Section: Dissolutionmentioning

confidence: 97%

Kinetic model framework for aerosol and cloud surface chemistry and gas-particle interactions – Part 1: General equations, parameters, and terminology

2007

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Abstract. Aerosols and clouds play central roles in atmospheric chemistry and physics, climate, air pollution, and public health. The mechanistic understanding and predictability of aerosol and cloud properties, interactions, transformations, and effects are, however, still very limited. This is due not only to the limited availability of measurement data, but also to the limited applicability and compatibility of model formalisms used for the analysis, interpretation, and description of heterogeneous and multiphase processes. To support the investigation and elucidation of atmospheric aerosol and cloud surface chemistry and gasparticle interactions, we present a comprehensive kinetic model framework with consistent and unambiguous terminology and universally applicable rate equations and parameters. It enables a detailed description of mass transport and chemical reactions at the gas-particle interface, and it allows linking aerosol and cloud surface processes with gas phase and particle bulk processes in systems with multiple chemical components and competing physicochemical processes.The key elements and essential aspects of the presented framework are: a simple and descriptive double-layer surface model (sorption layer and quasi-static layer); straightforward flux-based mass balance and rate equations; clear separation of mass transport and chemical reactions; well-defined and consistent rate parameters (uptake and accommodation coefficients, reaction and transport rate coefficients); clear distinction between gas phase, gas-surface, and surfacebulk transport (gas phase diffusion, surface and bulk accommodation); clear distinction between gas-surface, surface layer, and surface-bulk reactions (Langmuir-Hinshelwood and Eley-Rideal mechanisms); mechanistic description of The outlined double-layer surface concept and formalisms represent a minimum of model complexity required for a consistent description of the non-linear concentration and time dependences observed in experimental studies of atmospheric multiphase processes (competitive co-adsorption and surface saturation effects, etc.). Exemplary practical applications and model calculations illustrating the relevance of the above aspects are presented in a companion paper (Ammann and Pöschl, 2007).We expect that the presented model framework will serve as a useful tool and basis for experimental and theoretical studies investigating and describing atmospheric aerosol and cloud surface chemistry and gas-particle interactions. It shall help to end the "Babylonian confusion" that seems to inhibit scientific progress in the understanding of heterogeneous chemical reactions and other multiphase processes in aerosols and clouds. In particular, it shall support the planning and design of laboratory experiments for the elucidation and determination of fundamental kinetic parameters; the establishment, evaluation, and quality assurance of comprehensive and self-consistent collections of rate parameters; and the development of detailed master mechanisms for process mo...

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“…This small coordination number is also consistent with recently proposed electronic structure calculations for hydrated MA in small water clusters 64 and on similar studies on surface-bound state for ammonia. 69 Nevertheless, the solute-solvent interaction appears to not be the only factor favoring the surface preference. Carignano et al 70 have shown that, in the case of ammonia, there is also an energetic cost to rearrange the solvent molecules around the solute.…”

Section: E Hydrogen Bonding Network Surrounding Mamentioning

confidence: 99%

Hydrogen bonding and orientation effects on the accommodation of methylamine at the air-water interface

Hoehn

Carignano

Kais

et al. 2016

The Journal of Chemical Physics

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Methylamine is an abundant amine compound detected in the atmosphere which can affect the nature of atmospheric aerosol surfaces, changing their chemical and optical properties. Molecular dynamics simulation results show that methylamine accommodation on water is close to unity with the hydrophilic head group solvated in the interfacial environment and the methyl group pointing into the air phase. A detailed analysis of the hydrogen bond network indicates stronger hydrogen bonds between water and the primary amine group at the interface, suggesting that atmospheric trace gases will likely react with the methyl group instead of the solvated amine site. These findings suggest new chemical pathways for methylamine acting on atmospheric aerosols in which the methyl group is the site of orientation specific chemistry involving its conversion into a carbonyl site providing hydrophilic groups for uptake of additional water. This conversion may explain the tendency of aged organic aerosols to form cloud condensation nuclei. At the same time, formation of NH 2 radical and formaldehyde is suggested to be a new source for NH 2 radicals at aerosol surfaces, other than by reaction of absorbed NH 3 . The results have general implications for the chemistry of other amphiphilic organics, amines in particular, at the surface of atmospherically relevant aerosols. Published by AIP Publishing. [http://dx

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Adsorption of Atmospheric Gases at the Air−Water Interface. I. NH₃

Cited by 147 publications

References 31 publications

Detailed modeling of the evaporation and thermal decomposition of urea‐water solution in SCR systems

Detailed modeling of the evaporation and thermal decomposition of urea‐water solution in SCR systems

Kinetic model framework for aerosol and cloud surface chemistry and gas-particle interactions – Part 1: General equations, parameters, and terminology

Hydrogen bonding and orientation effects on the accommodation of methylamine at the air-water interface

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Adsorption of Atmospheric Gases at the Air−Water Interface. I. NH3

Cited by 147 publications

References 31 publications

Detailed modeling of the evaporation and thermal decomposition of urea‐water solution in SCR systems

Detailed modeling of the evaporation and thermal decomposition of urea‐water solution in SCR systems

Kinetic model framework for aerosol and cloud surface chemistry and gas-particle interactions – Part 1: General equations, parameters, and terminology

Hydrogen bonding and orientation effects on the accommodation of methylamine at the air-water interface

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Adsorption of Atmospheric Gases at the Air−Water Interface. I. NH₃