Search results for "aerosolit"
showing 7 items of 7 documents
A predictive model for salt nanoparticle formation using heterodimer stability calculations
2021
Acid–base clusters and stable salt formation are critical drivers of new particle formation events in the atmosphere. In this study, we explore salt heterodimer (a cluster of one acid and one base) stability as a function of gas-phase acidity, aqueous-phase acidity, heterodimer proton transference, vapor pressure, dipole moment and polarizability for salts comprised of sulfuric acid, methanesulfonic acid and nitric acid with nine bases. The best predictor of heterodimer stability was found to be gas-phase acidity. We then analyzed the relationship between heterodimer stability and J4×4, the theoretically predicted formation rate of a four-acid, four-base cluster, for sulfuric acid salts ove…
Microscopic Insights Into the Formation of Methanesulfonic Acid–Methylamine–Ammonia Particles Under Acid-Rich Conditions
2022
Understanding the microscopic mechanisms of new particle formation under acid-rich conditions is of significance in atmospheric science. Using quantum chemistry calculations, we investigated the microscopic formation mechanism of methanesulfonic acid (MSA)–methylamine (MA)–ammonia (NH3) clusters. We focused on the binary (MSA)2n-(MA)n and ternary (MSA)3n-(MA)n-(NH3)n, (n = 1–4) systems which contain more acid than base molecules. We found that the lowest-energy isomers in each system possess considerable thermodynamic and dynamic stabilities. In studied cluster structures, all bases are protonated, and they form stable ion pairs with MSA, which contribute to the charge transfer and the stab…
Modeling atmospheric aging of small-scale wood combustion emissions: distinguishing causal effects from non-causal associations
2022
Small-scale wood combustion is a significant source of particulate emissions. Atmospheric transformation of wood combustion emissions is a complex process involving multiple compounds interacting simultaneously. Thus, an advanced methodology is needed to study the process in order to gain a deeper understanding of the emissions. In this study, we are introducing a methodology for simplifying this complex process by detecting dependencies of observed compounds based on a measured dataset. A statistical model was fitted to describe the evolution of combustion emissions with a system of differential equations derived from the measured data. The performance of the model was evaluated using simu…
Effects of waste treatment technique and quality of waste on bioaerosols in Finnish waste treatment plants
2004
Outi Tolvanen selvitti tutkimuksessaan mikrobi-, endotoksiini- ja pölypitoisuuksia suomalaisilla jätteenkäsittelylaitoksilla. Tolvanen tutki, onko jätteiden tehostunut syntypistelajittelu ja jätteiden käsittely suljetuissa laitoksissa vähentänyt bioaerosolien ja pölyn aiheuttamia työhygieenisiä ongelmia. Kohonneiden mikrobipitoisuuksien on aikaisemmissa tutkimuksissa havaittu aiheuttavan jätteitä työssään käsitteleville henkilöille erilaisia oireita, kuten pahoinvointia, päänsärkyä, kuumeilua sekä allergiaa ja astmaa. The last fifteen years have seen immense changes in waste treatment in Finland. The number of landfill sites has been reduced and new waste treatment plants have been construc…
Molecular properties affecting the hydration of acid-base clusters
2021
In the atmosphere, water in all phases is ubiquitous and plays important roles in catalyzing atmospheric chemical reactions, participating in cluster formation and affecting the composition of aerosol particles. Direct measurements of water-containing clusters are limited because water is likely to evaporate before detection, and therefore, theoretical tools are needed to study hydration in the atmosphere. We have studied thermodynamics and population dynamics of the hydration of different atmospherically relevant base monomers as well as sulfuric acid–base pairs. The hydration ability of a base seems to follow in the order of gas-phase base strength whereas hydration ability of acid–base p…
Saturation vapor pressure characterization of selected low-volatility organic compounds using a residence time chamber
2023
Saturation vapor pressure (psat) is an important thermodynamic property regulating the gas-to-particle partitioning of organic compounds in the atmosphere. Low-volatility organic compounds (LVOCs), with sufficiently low psat values, primarily stay in the particle phase and contribute to aerosol formation. Obtaining accurate information on the psat of LVOCs requires volatility measurements performed at temperatures relevant to atmospheric aerosol formation. Here, we present an isothermal evaporation method using a residence time chamber to measure psat for dry single-compound nanoparticles at 295 K. Our method is able to characterize organic compounds with psat spanning from 10−8 to 10−4 Pa …
Predicting liquid–liquid phase separation in ternary organic–organic–water mixtures
2023
Liquid–liquid phase separation (LLPS) affects the water uptake of aerosol particles in the atmosphere through Kelvin and Raoult effects. This study investigates LLPS in ternary mixtures containing water and two organic compounds, using a conductor-like screening model for real solvents (COSMO-RS). COSMO-RS found LLPS in all of the studied mixtures containing water and proxies for primary and secondary organic aerosol (POA and SOA, respectively), due to the limited solubility of the hydrophobic POA proxies in water. The computations predict additional three-phase states in some of the SOA–POA–water mixtures at relative humidity (RH) close to 100%, which was not observed in experiments, likel…