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Publications (10 of 17) Show all publications
Olenius, T., Heitto, A., Roldin, P., Yli-Juuti, T. & Duwig, C. (2021). Modeling of exhaust gas cleaning by acid pollutant conversion to aerosol particles. Fuel, 290, Article ID 120044.
Open this publication in new window or tab >>Modeling of exhaust gas cleaning by acid pollutant conversion to aerosol particles
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2021 (English)In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 290, article id 120044Article in journal (Refereed) Published
Abstract [en]

Sulfur and nitrogen oxides (SOx and NOx) are harmful pollutants emitted into the atmosphere by industry and transport sectors. In addition to being hazardous gases, SOx and NOx form sulfuric and nitric acids which contribute to the formation of airborne particulate matter through nucleation and condensation, hence magnifying the environmental impact of these species. In this work, we build a modeling framework for utilizing this phenomenon for low-temperature exhaust gas cleaning. It has been reported that ammonia gas can be used to facilitate particle formation from the aforementioned acids, and thus remove these gaseous pollutants by converting them into ammonium sulfate and nitrate particles. Here we provide comprehensive modeling tools for applying this idea to exhaust gas cleaning by combining detailed models for nucleation, gas-particle mass exchange and particle population dynamics. We demonstrate how these models can be used to find advantageous operating conditions for a cleaning unit. In particular, the full model is computationally cheap and enables optimization of the particle formation efficiency and particle growth, hence ensuring sufficient conversion of gaseous pollutants into collectable particulate matter. This constitutes a ground for future engineering tools for designing next-generation sustainable exhaust gas cleaners.

Keywords
Exhaust gas cleaning, Modeling, De-SOx, De-NOx, Aerosol, Nanoparticle formation
National Category
Environmental Engineering Chemical Engineering Mechanical Engineering
Identifiers
urn:nbn:se:su:diva-192019 (URN)10.1016/j.fuel.2020.120044 (DOI)000618104400006 ()
Available from: 2021-04-14 Created: 2021-04-14 Last updated: 2022-02-25Bibliographically approved
Shcherbacheva, A., Balehowsky, T., Kubečka, J., Olenius, T., Helin, T., Haario, H., . . . Vehkamäki, H. (2020). Identification of molecular cluster evaporation rates, cluster formation enthalpies and entropies by Monte Carlo method. Atmospheric Chemistry And Physics, 20(24), 15867-15906
Open this publication in new window or tab >>Identification of molecular cluster evaporation rates, cluster formation enthalpies and entropies by Monte Carlo method
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2020 (English)In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 20, no 24, p. 15867-15906Article in journal (Refereed) Published
Abstract [en]

We address the problem of identifying the evaporation rates for neutral molecular clusters from synthetic (computer-simulated) cluster concentrations. We applied Bayesian parameter estimation using a Markov chain Monte Carlo (MCMC) algorithm to determine cluster evaporation/fragmentation rates from synthetic cluster distributions generated by the Atmospheric Cluster Dynamics Code (ACDC) and based on gas kinetic collision rate coefficients and evaporation rates obtained using quantum chemical calculations and detailed balances. The studied system consisted of electrically neutral sulfuric acid and ammonia clusters with up to five of each type of molecules. We then treated the concentrations generated by ACDC as synthetic experimental data. With the assumption that the collision rates are known, we tested two approaches for estimating the evaporation rates from these data. First, we studied a scenario where time-dependent cluster distributions are measured at a single temperature before the system reaches a steady state. In the second scenario, only steady-state cluster distributions are measured but at several temperatures. Additionally, in the latter case, the evaporation rates were represented in terms of cluster formation enthalpies and entropies. This reparame-terization reduced the number of unknown parameters, since several evaporation rates depend on the same cluster formation enthalpy and entropy values. We also estimated the evap- oration rates using previously published synthetic steady-state cluster concentration data at one temperature and compared our two cases to this setting. Both the time-dependent and the two-temperature steady-state concentration data allowed us to estimate the evaporation rates with less variance than in the steady-state single-temperature case. We show that temperature-dependent steady-state data outperform single-temperature time-dependent data for parameter estimation, even if only two temperatures are used. We can thus conclude that for experimentally determining evaporation rates, cluster distribution measurements at several temperatures are recommended over time-dependent measurements at one temperature.

National Category
Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:su:diva-190644 (URN)10.5194/acp-20-15867-2020 (DOI)000602506700002 ()
Available from: 2021-03-05 Created: 2021-03-05 Last updated: 2022-02-25Bibliographically approved
Schlesinger, D., Lowe, S. J., Olenius, T., Kong, X., Pettersson, J. B. C. & Riipinen, I. (2020). Molecular Perspective on Water Vapor Accommodation into Ice and Its Dependence on Temperature. Journal of Physical Chemistry A, 124(51), 10879-10889
Open this publication in new window or tab >>Molecular Perspective on Water Vapor Accommodation into Ice and Its Dependence on Temperature
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2020 (English)In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 124, no 51, p. 10879-10889Article in journal (Refereed) Published
Abstract [en]

Accommodation of vapor-phase water molecules into ice crystal surfaces is a fundamental process controlling atmospheric ice crystal growth. Experimental studies investigating the accommodation process with various techniques report widely spread values of the water accommodation coefficient on ice, αice, and the results on its potential temperature dependence are inconclusive. We run molecular dynamics simulations of molecules condensing onto the basal plane of ice Ih using the TIP4P/Ice empirical force field and characterize the accommodated state from this molecular perspective, utilizing the interaction energy, the tetrahedrality order parameter, and the distance below the instantaneous interface as criteria. Changes of the order parameter turn out to be a suitable measure to distinguish between the surface and bulk states of a molecule condensing onto the disordered interface. In light of the findings from the molecular dynamics, we discuss and re-analyze a recent experimental data set on αice obtained with an environmental molecular beam (EMB) setup [Kong, X.; J. Phys. Chem. A 2014, 118 (22), 3973−3979] using kinetic molecular flux modeling, aiming at a more comprehensive picture of the accommodation process from a molecular perspective. These results indicate that the experimental observations indeed cannot be explained by evaporation alone. At the same time, our results raise the issue of rapidly growing relaxation times upon decreasing temperature, challenging future experimental efforts to cover relevant time scales. Finally, we discuss the relevance of the water accommodation coefficient on ice in the context of atmospheric cloud particle growth processes. 

National Category
Other Physics Topics Physical Chemistry
Identifiers
urn:nbn:se:su:diva-212828 (URN)10.1021/acs.jpca.0c09357 (DOI)000603402600024 ()33319553 (PubMedID)2-s2.0-85098779290 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation, 2015.0162EU, Horizon 2020, 821205EU, Horizon 2020, 865799ÅForsk (Ångpanneföreningen's Foundation for Research and Development), 18-334
Available from: 2022-12-13 Created: 2022-12-13 Last updated: 2023-02-13Bibliographically approved
Carlsson, P. T. M., Celik, S., Becker, D., Olenius, T., Elm, J. & Zeuch, T. (2020). Neutral Sulfuric Acid-Water Clustering Rates: Bridging the Gap between Molecular Simulation and Experiment. The Journal of Physical Chemistry Letters, 11(10), 4239-4244
Open this publication in new window or tab >>Neutral Sulfuric Acid-Water Clustering Rates: Bridging the Gap between Molecular Simulation and Experiment
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2020 (English)In: The Journal of Physical Chemistry Letters, E-ISSN 1948-7185, Vol. 11, no 10, p. 4239-4244Article in journal (Refereed) Published
Abstract [en]

The role of sulfuric acid during atmospheric new particle formation is an ongoing topic of discussion. In this work, we provide quantitative experimental constraints for quantum chemically calculated evaporation rates for the smallest H2SO4-H2O clusters, characterizing the mechanism governing nucleation on a kinetic, single-molecule level. We compare experimental particle size distributions resulting from a highly supersaturated homogeneous H2SO4 gas phase with the results from kinetic simulations employing quantum chemically derived decomposition rates of electrically neutral H2SO4 molecular clusters up to the pentamer at a large range of relative humidities. By using high H2SO4 concentrations, we circumvent the uncertainties concerning contaminants and competing reactions present in studies at atmospheric conditions. We show good agreement between molecular simulation and experimental measurements and provide the first evaluation of theoretical predictions of the stabilization provided by water molecules.

National Category
Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:su:diva-182950 (URN)10.1021/acs.jpclett.0c01045 (DOI)000537432500069 ()32357300 (PubMedID)
Available from: 2020-07-09 Created: 2020-07-09 Last updated: 2024-07-04Bibliographically approved
Myllys, N., Chee, S., Olenius, T., Lawler, M. & Smith, J. (2019). Molecular-Level Understanding of Synergistic Effects in Sulfuric Acid-Amine-Ammonia Mixed Clusters. Journal of Physical Chemistry A, 123(12), 2420-2425
Open this publication in new window or tab >>Molecular-Level Understanding of Synergistic Effects in Sulfuric Acid-Amine-Ammonia Mixed Clusters
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2019 (English)In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 123, no 12, p. 2420-2425Article in journal (Refereed) Published
Abstract [en]

The abundance and basicity of a stabilizing base have shown to be key factors in sulfuric acid driven atmospheric new-particle formation. However, since experiments indicate that a low concentration of ammonia enhances particle formation from sulfuric acid and dimethylamine, which is a stronger base, there must be additional factors affecting the particle formation efficiency. Using quantum chemistry, we provide a molecular-level explanation for the synergistic effects in sulfuric acid-dimethylamine-ammonia cluster formation. Because of the capability of ammonia to form more intermolecular interactions than dimethylamine, it can act as a bridge-former in sulfuric acid-dimethylamine clusters. In many cluster compositions, ammonia is more likely to be protonated than dimethylamine, although it is a weaker base. By nanoparticle formation rate simulations, we show that due to the synergistic effects, ammonia can increase the particle formation rate by up to 5 orders of magnitude compared to the two-component sulfuric acid-amine system.

National Category
Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:su:diva-168613 (URN)10.1021/acs.jpca.9b00909 (DOI)000463116200012 ()30821984 (PubMedID)
Available from: 2019-05-10 Created: 2019-05-10 Last updated: 2022-02-26Bibliographically approved
Myllys, N., Kubecka, J., Besel, V., Alfaouri, D., Olenius, T., Norman Smith, J. & Passananti, M. (2019). Role of base strength, cluster structure and charge in sulfuric-acid-driven particle formation. Atmospheric Chemistry And Physics, 19(15), 9753-9768
Open this publication in new window or tab >>Role of base strength, cluster structure and charge in sulfuric-acid-driven particle formation
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2019 (English)In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 19, no 15, p. 9753-9768Article in journal (Refereed) Published
Abstract [en]

In atmospheric sulfuric-acid-driven particle formation, bases are able to stabilize the initial molecular clusters and thus enhance particle formation. The enhancing potential of a stabilizing base is affected by different factors, such as the basicity and abundance. Here we use weak (ammonia), medium strong (dimethylamine) and very strong (guanidine) bases as representative atmospheric base compounds, and we systematically investigate their ability to stabilize sulfuric acid clusters. Using quantum chemistry, we study proton transfer as well as intermolecular interactions and symmetry in clusters, of which the former is directly related to the base strength and the latter to the structural effects. Based on the theoretical cluster stabilities and cluster population kinetics modeling, we provide molecular-level mechanisms of cluster growth and show that in electrically neutral particle formation, guanidine can dominate formation events even at relatively low concentrations. However, when ions are involved, charge effects can also stabilize small clusters for weaker bases. In this case the atmospheric abundance of the bases becomes more important, and thus ammonia is likely to play a key role. The theoretical findings are validated by cluster distribution experiments, as well as comparisons to previously reported particle formation rates, showing a good agreement.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:su:diva-171958 (URN)10.5194/acp-19-9753-2019 (DOI)000478696200002 ()
Available from: 2019-09-04 Created: 2019-09-04 Last updated: 2025-02-07Bibliographically approved
Roldin, P., Ehn, M., Kurtén, T., Olenius, T., Rissanen, M. P., Sarnela, N., . . . Boy, M. (2019). The role of highly oxygenated organic molecules in the Boreal aerosol-cloud-climate system. Nature Communications, 10, Article ID 4370.
Open this publication in new window or tab >>The role of highly oxygenated organic molecules in the Boreal aerosol-cloud-climate system
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2019 (English)In: Nature Communications, E-ISSN 2041-1723, Vol. 10, article id 4370Article in journal (Refereed) Published
Abstract [en]

Over Boreal regions, monoterpenes emitted from the forest are the main precursors for secondary organic aerosol (SOA) formation and the primary driver of the growth of new aerosol particles to climatically important cloud condensation nuclei (CCN). Autoxidation of monoterpenes leads to rapid formation of Highly Oxygenated organic Molecules (HOM). We have developed the first model with near-explicit representation of atmospheric new particle formation (NPF) and HOM formation. The model can reproduce the observed NPF, HOM gas-phase composition and SOA formation over the Boreal forest. During the spring, HOM SOA formation increases the CCN concentration by similar to 10 % and causes a direct aerosol radiative forcing of -0.10 W/m(2). In contrast, NPF reduces the number of CCN at updraft velocities < 0.2 m/s, and causes a direct aerosol radiative forcing of +0.15 W/m(2). Hence, while HOM SOA contributes to climate cooling, NPF can result in climate warming over the Boreal forest.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:su:diva-175049 (URN)10.1038/s41467-019-12338-8 (DOI)000487585600031 ()31554809 (PubMedID)
Available from: 2019-10-29 Created: 2019-10-29 Last updated: 2025-02-07Bibliographically approved
Kontkanen, J., Olenius, T., Kulmala, M. & Riipinen, I. (2018). Exploring the potential of nano-Kohler theory to describe the growth of atmospheric molecular clusters by organic vapors using cluster kinetics simulations. Atmospheric Chemistry And Physics, 18(18), 13733-13754
Open this publication in new window or tab >>Exploring the potential of nano-Kohler theory to describe the growth of atmospheric molecular clusters by organic vapors using cluster kinetics simulations
2018 (English)In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 18, no 18, p. 13733-13754Article in journal (Refereed) Published
Abstract [en]

Atmospheric new particle formation (NPF) occurs by the formation of nanometer-sized molecular clusters and their subsequent growth to larger particles. NPF involving sulfuric acid, bases and oxidized organic compounds is an important source of atmospheric aerosol particles. One of the mechanisms suggested to depict this process is nano-Kohler theory, which describes the activation of inorganic molecular clusters to growth by a soluble organic vapor. In this work, we studied the capability of nano-Kohler theory to describe the initial growth of atmospheric molecular clusters by simulating the dynamics of a cluster population in the presence of a sulfuric acid-base mixture and an organic compound. We observed nano-Kohler-type activation in our simulations when the saturation ratio of the organic vapor and the ratio between organic and inorganic vapor concentrations were in a suitable range. However, nano-Kohler theory was unable to predict the exact size at which the activation occurred in the simulations. In some conditions, apparent cluster growth rate (GR) started to increase close to the activation size determined from the simulations. Nevertheless, because the behavior of GR is also affected by other dynamic processes, GR alone cannot be used to deduce the cluster growth mechanism.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:su:diva-161186 (URN)10.5194/acp-18-13733-2018 (DOI)000445784700006 ()
Available from: 2018-11-02 Created: 2018-11-02 Last updated: 2025-02-07Bibliographically approved
Myllys, N., Ponkkonen, T., Passananti, M., Elm, J., Vehkämaki, H. & Olenius, T. (2018). Guanidine: A Highly Efficient Stabilizer in Atmospheric New-Particle Formation. Journal of Physical Chemistry A, 122(20), 4717-4729
Open this publication in new window or tab >>Guanidine: A Highly Efficient Stabilizer in Atmospheric New-Particle Formation
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2018 (English)In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 122, no 20, p. 4717-4729Article in journal (Refereed) Published
Abstract [en]

The role of a strong organobase, guanidine, in sulfuric acid-driven new-particle formation is studied using state-of-the-art quantum chemical methods and molecular cluster formation simulations. Cluster formation mechanisms at the molecular level are resolved, and theoretical results on cluster stability are confirmed with mass spectrometer measurements. New-particle formation from guanidine and sulfuric acid molecules occurs without thermodynamic barriers under studied conditions, and clusters are growing close to a 1:1 composition of acid and base. Evaporation rates of the most stable clusters are extremely low, which can be explained by the proton transfers and symmetrical cluster structures. We compare the ability of guanidine and dimethylamine to enhance sulfuric acid-driven particle formation and show that more than 2000-fold concentration of dimethylamine is needed to yield as efficient particle formation as in the case of guanidine. At similar conditions, guanidine yields 8 orders of magnitude higher particle formation rates compared to dimethylamine. Highly basic compounds such as guanidine may explain experimentally observed particle formation events at low precursor vapor concentrations, whereas less basic and more abundant bases such as ammonia and amines are likely to explain measurements at high concentrations.

National Category
Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:su:diva-157728 (URN)10.1021/acs.jpca.8b02507 (DOI)000433403700004 ()29693391 (PubMedID)
Available from: 2018-08-02 Created: 2018-08-02 Last updated: 2022-02-26Bibliographically approved
Julin, J., Murphy, B. N., Patoulias, D., Fountoukis, C., Olenius, T., Pandis, S. N. & Riipinen, I. (2018). Impacts of Future European Emission Reductions on Aerosol Particle Number Concentrations Accounting for Effects of Ammonia, Amines, and Organic Species. Environmental Science and Technology, 52(2), 692-700
Open this publication in new window or tab >>Impacts of Future European Emission Reductions on Aerosol Particle Number Concentrations Accounting for Effects of Ammonia, Amines, and Organic Species
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2018 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 52, no 2, p. 692-700Article in journal (Refereed) Published
Abstract [en]

Although they are currently unregulated, atmospheric ultrafine particles (<100 nm) pose health risks because of, e.g., their capability to penetrate deep into the respiratory system. Ultrafine particles, often minor contributors to atmospheric particulate mass, typically dominate aerosol particle number concentrations. We simulated the response of particle number concentrations over Europe to recent estimates of future emission reductions of aerosol particles and their precursors. We used the chemical transport model PMCAMx-UF, with novel updates including state-of-the-art descriptions of ammonia and dimethylamine new particle formation (NPF) pathways and the condensation of organic compounds onto particles. These processes had notable impacts on atmospheric particle number concentrations. All three emission scenarios (current legislation, optimized emissions, and maximum technically feasible reductions) resulted in substantial (10-50%) decreases in median particle number concentrations over Europe. Consistent reductions were predicted in Central Europe, while Northern Europe exhibited smaller reductions or even increased concentrations. Motivated by the improved NPF descriptions for ammonia and methylamines, we placed special focus on the potential to improve air quality by reducing agricultural emissions,, which are a major source of these species. Agricultural emission controls showed promise in reducing ultrafine particle number concentrations, although the change is nonlinear with particle size.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:su:diva-152725 (URN)10.1021/acs.est.7b05122 (DOI)000423012200034 ()29185762 (PubMedID)
Available from: 2018-02-26 Created: 2018-02-26 Last updated: 2025-02-07Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-9900-3081

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