scholarly journals Effects of oligomerization and decomposition to the nanoparticle growth, a model study

2021 ◽  
Author(s):  
Arto Heitto ◽  
Kari Lehtinen ◽  
Tuukka Petäjä ◽  
Felipe Lopez-Hilfiker ◽  
Joel A. Thornton ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Reaction Rates ◽  
Climate Impacts ◽  
Basis Set ◽  
Base Case ◽  
Particle Phase ◽  
Maximum Increase ◽  
Organic Vapors ◽  
Nanoparticle Growth ◽  
Model Study

Abstract. The rate at which freshly formed secondary aerosol particles grow is an important factor in determining their climate impacts. The growth rate of atmospheric nanoparticles may be affected by particle phase oligomerization and decomposition of condensing organic molecules. We used Model for Oligomerization and Decomposition in Nanoparticle Growth (MODNAG) to investigate the potential atmospheric significance of these effects. This was done by conducting multiple simulations with varying reaction-related parameters (volatilities of the involved compounds and reaction rates) using both artificial and ambient measured gas phase concentrations of organic vapors to define the condensing vapors. While our study does not aim at providing information on any specific reaction, our results indicate that particle phase reactions have significant potential to affect the nanoparticle growth. In simulations where one-third of a volatility basis set bin was allowed to go through particle phase reactions the maximum increase in growth rates was 71 % and decrease 26 % compared to base case where no particle phase reactions were assumed to take place. These results highlight the importance of investigating and increasing our understanding of particle phase reactions.

scholarly journals Effects of oligomerization and decomposition on the nanoparticle growth: a model study

2022 ◽  
Vol 22 (1) ◽  
pp. 155-171
Author(s):  
Arto Heitto ◽  
Kari Lehtinen ◽  
Tuukka Petäjä ◽  
Felipe Lopez-Hilfiker ◽  
Joel A. Thornton ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Reaction Rates ◽  
Climate Impacts ◽  
Basis Set ◽  
Base Case ◽  
Particle Phase ◽  
Maximum Increase ◽  
Organic Vapors ◽  
Nanoparticle Growth ◽  
Model Study

Abstract. The rate at which freshly formed secondary aerosol particles grow is an important factor in determining their climate impacts. The growth rate of atmospheric nanoparticles may be affected by particle-phase oligomerization and decomposition of condensing organic molecules. We used the Model for Oligomerization and Decomposition in Nanoparticle Growth (MODNAG) to investigate the potential atmospheric significance of these effects. This was done by conducting multiple simulations with varying reaction-related parameters (volatilities of the involved compounds and reaction rates) using both artificial and ambient measured gas-phase concentrations of organic vapors to define the condensing vapors. While our study does not aim at providing information on any specific reaction, our results indicate that particle-phase reactions have significant potential to affect the nanoparticle growth. In simulations in which one-third of a volatility basis set bin was allowed to go through particle-phase reactions, the maximum increase in growth rates was 71 % and the decrease 26 % compared to the base case in which no particle-phase reactions were assumed to take place. These results highlight the importance of investigating and increasing our understanding of particle-phase reactions.

scholarly journals Molecular identification of organic vapors driving atmospheric nanoparticle growth

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Claudia Mohr ◽  
Joel A. Thornton ◽  
Arto Heitto ◽  
Felipe D. Lopez-Hilfiker ◽  
Anna Lutz ◽  
...  
Keyword(s):  
Molecular Level ◽  
Cloud Condensation Nuclei ◽  
Particle Growth ◽  
Climate Forcing ◽  
Particle Phase ◽  
Organic Vapors ◽  
Nanoparticle Growth ◽  
Atmospheric Particle ◽  
Aerosol Cloud Interactions

Abstract Particles formed in the atmosphere via nucleation provide about half the number of atmospheric cloud condensation nuclei, but in many locations, this process is limited by the growth of the newly formed particles. That growth is often via condensation of organic vapors. Identification of these vapors and their sources is thus fundamental for simulating changes to aerosol-cloud interactions, which are one of the most uncertain aspects of anthropogenic climate forcing. Here we present direct molecular-level observations of a distribution of organic vapors in a forested environment that can explain simultaneously observed atmospheric nanoparticle growth from 3 to 50 nm. Furthermore, the volatility distribution of these vapors is sufficient to explain nanoparticle growth without invoking particle-phase processes. The agreement between observed mass growth, and the growth predicted from the observed mass of condensing vapors in a forested environment thus represents an important step forward in the characterization of atmospheric particle growth.

A Model Study on the Adsorption of Small Molecules on Organic Molecules and Polymers

1990 ◽  
pp. 387-391
Author(s):  
Shang Zhang Liu ◽  
Yang Gao ◽  
Lin You Wu ◽  
Bao Qiang Yu ◽  
Shu Min Jiang
Keyword(s):  
Small Molecules ◽  
Organic Molecules ◽  
Model Study

scholarly journals Predictions of diffusion rates of organic molecules in secondary organic aerosols using the Stokes-Einstein and fractional Stokes-Einstein relations

2019 ◽  
Author(s):  
Erin Evoy ◽  
Adrian M. Maclean ◽  
Grazia Rovelli ◽  
Ying Li ◽  
Alexandra P. Tsimpidi ◽  
...  
Keyword(s):  
Citric Acid ◽  
Organic Molecules ◽  
Transport Model ◽  
Reaction Rates ◽  
Einstein Relation ◽  
Acid Mixture ◽  
Chemical Transport Model ◽  
Order Of Magnitude ◽  
Diffusion Rates ◽  
Almost All

Abstract. Information on the rate of diffusion of organic molecules within secondary organic aerosol (SOA) is needed to accurately predict the effects of SOA on climate and air quality. Often, researchers have predicted diffusion rates of organic molecules within SOA using measurements of viscosity and the Stokes-Einstein relation (D ∝ 1/η where D is the diffusion coefficient and η is viscosity). However, the accuracy of this relation for predicting diffusion in SOA remains uncertain. We measured diffusion coefficients over eight orders in magnitude in proxies of SOA including citric acid, sorbitol, and a sucrose-citric acid mixture. These results were combined with literature data to evaluate the Stokes-Einstein relation for predicting diffusion of organic molecules in SOA. Although almost all the data agrees with the Stokes-Einstein relation within a factor of ten, a fractional Stokes-Einstein relation (D ∝ C/ηt) with t = 0.93 and C = 1.66 is a better model for predicting diffusion of organic molecules in the SOA proxies studied. In addition, based on the output from a chemical transport model, the Stokes-Einstein relation can over predict mixing times of organic molecules within SOA by as much as one order of magnitude at an altitude ~ 3 km, compared to the fractional Stokes-Einstein relation with t = 0.93 and C = 1.66. These differences can be important for predicting growth, evaporation, and reaction rates of SOA in the middle and upper part of the troposphere. These results also have implications for other areas where diffusion of organic molecules within organic-water matrices is important.

Monomer basis-set truncation effects in calculations of interaction energies: A model study

2004 ◽  
Vol 120 (17) ◽  
pp. 7837-7848 ◽  
Author(s):  
Anna Kaczmarek ◽  
Andrzej J. Sadlej ◽  
Jerzy Leszczynski
Keyword(s):  
Basis Set ◽  
Interaction Energies ◽  
Model Study

Interstellar carbon chemistry: Reaction rates of neutral atomic carbon with organic molecules

1994 ◽  
Vol 422 ◽  
pp. 416 ◽  
Author(s):  
D. C. Clary ◽  
N. Haider ◽  
D. Husain ◽  
M. Kabir
Keyword(s):  
Organic Molecules ◽  
Reaction Rates ◽  
Atomic Carbon ◽  
Carbon Chemistry

scholarly journals On the fate of oxygenated organic molecules in atmospheric aerosol particles

2020 ◽  
Vol 6 (11) ◽  
pp. eaax8922 ◽  
Author(s):  
V. Pospisilova ◽  
F. D. Lopez-Hilfiker ◽  
D. M. Bell ◽  
I. El Haddad ◽  
C. Mohr ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Measurement Techniques ◽  
Organic Aerosol ◽  
Particle Phase ◽  
Ionization Time ◽  
Global Carbon Budget ◽  
Atmospheric Fate ◽  
Condensed Phase Reactions ◽  
Earth’S Climate ◽  
Global Carbon

Highly oxygenated organic molecules (HOMs) are formed from the oxidation of biogenic and anthropogenic gases and affect Earth’s climate and air quality by their key role in particle formation and growth. While the formation of these molecules in the gas phase has been extensively studied, the complexity of organic aerosol (OA) and lack of suitable measurement techniques have hindered the investigation of their fate post-condensation, although further reactions have been proposed. We report here novel real-time measurements of these species in the particle phase, achieved using our recently developed extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF). Our results reveal that condensed-phase reactions rapidly alter OA composition and the contribution of HOMs to the particle mass. In consequence, the atmospheric fate of HOMs cannot be described solely in terms of volatility, but particle-phase reactions must be considered to describe HOM effects on the overall particle life cycle and global carbon budget.

scholarly journals Improving the representation of secondary organic aerosol (SOA) in the MOZART-4 global chemical transport model

2012 ◽  
Vol 5 (4) ◽  
pp. 4187-4232 ◽  
Author(s):  
A. Mahmud ◽  
K. C. Barsanti
Keyword(s):  
South America ◽  
Secondary Organic Aerosol ◽  
Transport Model ◽  
Organic Aerosol ◽  
Basis Set ◽  
Base Case ◽  
Chemical Transport Model ◽  
Annual Average ◽  
Modeling Studies ◽  
The Usa

Abstract. The secondary organic aerosol (SOA) module in the Model for Ozone and Related chemical Tracers, version 4 (MOZART-4) has been updated by replacing existing two-product (2p) parameters with those obtained from two-product volatility basis set (2p-VBS) fits, and by treating SOA formation from the following volatile organic compounds (VOCs): isoprene, propene and lumped alkenes. Strong seasonal and spatial variations in global SOA distributions were demonstrated, with significant differences in the predicted concentrations between the base-case and updated model versions. The base-case MOZART-4 predicted annual average SOA of 0.36 ± 0.50 μg m−3 in South America, 0.31 ± 0.38 μg m−3 in Indonesia, 0.09 ± 0.05 μg m−3 in the USA, and 0.12 ± 0.07 μg m−3 in Europe. Concentrations from the updated versions of the model showed a~marked increase in annual average SOA. Using the updated set of parameters alone (MZ4-v1) increased annual average SOA by ~8%, ~16%, ~56%, and ~108% from the base-case in South America, Indonesia, USA, and Europe, respectively. Treatment of additional parent VOCs (MZ4-v2) resulted in an even more dramatic increase of ~178–406% in annual average SOA for these regions over the base-case. The increases in predicted SOA concentrations further resulted in increases in corresponding SOA contributions to annual average total aerosol optical depth (AOD) by <1% for MZ4-v1 and ~1–6% for MZ4-v2. Estimated global SOA production was ~6.6 Tg yr−1 and ~19.1 Tg yr−1 with corresponding burdens of ~0.24 Tg and ~0.59 Tg using MZ4-v1 and MZ4-v2, respectively. The SOA budgets predicted in the current study fall well within reported ranges for similar modeling studies, 6.7 to 96 Tg yr−1, but are lower than recently reported observationally-constrained values, 50 to 380 Tg yr−1. With MZ4-v2, simulated SOA concentrations at the surface were also in reasonable agreement with comparable modeling studies and observations. Concentrations of estimated organic aerosol (OA) at the surface, however, showed under-prediction in Europe and over-prediction in the Amazonian regions and Malaysian Borneo during certain months of the year. Overall, the updated version of MOZART-4, MZ4-v2, showed consistently better skill in predicting SOA and OA levels and spatial distributions as compared with unmodified MOZART-4. The MZ4-v2 updates may be particularly important when MOZART-4 output is used to generate boundary conditions for regional air quality simulations that require more accurate representation of SOA concentrations and distributions.

Iron Ore Sintering Process Based on Alternative Gaseous Fuels from Steelworks

2012 ◽  
Vol 535-537 ◽  
pp. 554-560 ◽  
Author(s):  
José Adilson de Castro ◽  
Vagner Silva Guilherme ◽  
Alexandre Boscaro França ◽  
Yasushi Sazaki
Keyword(s):  
Solid Fuel ◽  
Iron Ore ◽  
Chemical Species ◽  
Reaction Rates ◽  
Base Case ◽  
Temperature Pattern ◽  
Sintering Process ◽  
Fuel Gas ◽  
Gas Utilization ◽  
Model Predictions

This paper deals with the numerical simulation of the new technology of gaseous fuel utilization on the sintering process of iron ore. The proposed methodology is to partially replace the solid fuel(coke breeze) by steelworks gases. A multiphase mathematical model based on transport equations of momentum, energy and chemical species coupled with chemical reaction rates and phase transformations is proposed to analyze the inner process parameters. A base case representing the actual industrial operation of a large sintering machine is used with thermocouples inserted into the sintering bed to record the inner bed temperatures and compare with model predictions in order to obtain model validation and parameters adjustment. Good agreement of the temperature pattern was obtained for the base case and thus, the model was used to predict four cases of fuel gas utilization: a) 2% of the wind boxes inflow from N01-N15 wind boxes of natural gas(NG), b) same condition with coke oven gas(COG), c) same condition with blast furnace gas(BFG) and d) mixture of 50% COG and 50% BFG. The model predictions indicated that for all cases, except only BFG, the sintering zone is enlarged and the solid fuel consumption is decreased about 8kg/t of sinter product. In order to maximize the steelworks gas utilization it is recommended the use of mixture of COG and BFG with optimum inner temperature distribution

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