scholarly journals Influence of aerosol lifetime on the interpretation of nucleation experiments with respect to the first nucleation theorem

2013 ◽  
Vol 13 (22) ◽  
pp. 11465-11471 ◽  
Author(s):  
S. Ehrhart ◽  
J. Curtius
Keyword(s):  
Particle Size ◽  
Sulphuric Acid ◽  
Growth Rates ◽  
Nucleation Theory ◽  
Acid Water ◽  
Critical Cluster ◽  
Wall Losses ◽  
Nucleation Model ◽  
Nucleation Theorem

Abstract. The SAWNUC (Sulphuric Acid Water NUCleation) microphysical aerosol nucleation model is used to study the effect of reactor walls on the interpretation of nucleation experiments with respect to nucleation theory. This work shows that loss processes, such as wall losses, influence the interpretation of nucleation experiments, especially at low growth rates and short lifetimes of freshly nucleated particles. In these cases the power dependency of the formation rates, determined at a certain particle size, with respect to H2SO4 does not correspond to the approximate number of H2SO4 molecules in the critical cluster as expected by the first nucleation theorem. Observed ∂log(J)/∂log([H2SO4]) therefore can vary widely for identical nucleation conditions but different sink terms.

scholarly journals Influence of aerosol lifetime on the interpretation of nucleation experiments with respect to the first nucleation theorem

2013 ◽  
Vol 13 (4) ◽  
pp. 9733-9750
Author(s):  
S. Ehrhart ◽  
J. Curtius
Keyword(s):  
Particle Size ◽  
Growth Rates ◽  
Nucleation Theory ◽  
Critical Cluster ◽  
Short Lifetime ◽  
Wall Losses ◽  
Nucleation Model ◽  
Nucleation Theorem

Abstract. The SAWNUC microphysical aerosol nucleation model is used to study the effect of reactor walls on the interpretation of nucleation experiments with respect to nucleation theory. This work shows that loss processes, such as wall losses, influence the interpretation of nucleation experiments, especially at low growth rates and short lifetime of freshly nucleated particles. In these cases the power dependency of the formation rates, determined at a certain particle size, with respect to H2SO4 does not correspond to the approximate number of H2SO4 molecules in the critical cluster as expected by the first nucleation theorem. Observed ∂log(J)/∂log([H2SO4]) therefore can vary widely for identical nucleation conditions but different sink terms.

scholarly journals Growth of sulphuric acid nanoparticles under wet and dry conditions

2013 ◽  
Vol 13 (9) ◽  
pp. 24087-24125
Author(s):  
L. Škrabalová ◽  
D. Brus ◽  
T. Anttila ◽  
V. Ždímal ◽  
H. Lihavainen
Keyword(s):  
Relative Humidity ◽  
Sulphuric Acid ◽  
Ammonium Sulphate ◽  
Residence Time ◽  
Growth Rates ◽  
Initial Growth ◽  
Flow Tube ◽  
H2so4 Concentration ◽  
Wall Losses ◽  
Dry Conditions

Abstract. New particle formation, which greatly influences the number concentrations and size distributions of an atmospheric aerosol, is often followed by a rapid growth of freshly formed particles. The initial growth of a newly formed aerosol is the crucial process determining the fraction of nucleated particles growing into cloud condensation nuclei sizes, which have a significant influence on climate. In this study, we report the laboratory observations of the growth of nanoparticles produced by nucleation of H2SO4 and water in a laminar flow tube at temperatures of 283, 293 and 303 K, under dry (a relative humidity of 1%) and wet conditions (relative humidity of 30%) and residence times of 30, 45, 60 and 90 s. The initial H2SO4 concentration spans the range from 2 × 108 to 1.4 × 1010 molecule cm−3 and the calculated wall losses of H2SO4 were assumed to be diffusion limited. The detected particle number concentrations, measured by the Ultrafine Condensation Particle Counter (UCPC) and Differential Mobility Particle Sizer (DMPS), were found to depend strongly on the residence time. Hygroscopic particle growth, presented by growth factors, was found to be in good agreement with the previously reported studies. The experimental growth rates ranged from 20 nm h−1 to 890 nm h−1 at RH 1% and from 7 nm h−1 to 980 nm h−1 at RH 30% and were found to increase significantly with the increasing concentration of H2SO4. Increases in the nucleation temperature had a slight enhancing effect on the growth rates under dry conditions. The influence of relative humidity on growth was not consistent – at lower H2SO4 concentrations, the growth rates were higher under dry conditions while at H2SO4 concentrations greater than 1×109molecule cm−3 the growth rates were higher under wet conditions. The growth rates show only a weak dependence on the residence time. The experimental observations were compared with predictions made using a numerical model, which investigates the growth of particles with three different extents of neutralization by the ammonia NH3: (1) pure H2SO4 – H2O particles (2) particles formed by ammonium bisulphate, (NH4)HSO4 (3) particles formed by ammonium sulphate, (NH4)2SO4. The highest growth rates were found for ammonium sulphate particles. Since the model accounting for the initial H2SO4 concentration predicted the experimental growth rates correctly, our results suggest that the commonly presumed diffusional wall losses of H2SO4 are not so significant. We therefore assume that there are not only losses of H2SO4 on the wall but also a flux of H2SO4 molecules from the wall into the flow tube, the effect being more profound under dry conditions and at higher temperatures of the tube wall. Based on a comparison with the atmospheric observations, our results indicate that sulphuric acid alone can not explain the growth rates of particles formed in the atmosphere.

scholarly journals New particle formation events in semi-clean South African savannah

2011 ◽  
Vol 11 (7) ◽  
pp. 3333-3346 ◽  
Author(s):  
V. Vakkari ◽  
H. Laakso ◽  
M. Kulmala ◽  
A. Laaksonen ◽  
D. Mabaso ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Growth Rate ◽  
Particle Size ◽  
Sulphuric Acid ◽  
Growth Rates ◽  
Formation Rate ◽  
Particle Formation ◽  
Size Distributions ◽  
New Particle Formation ◽  
Particle Formation And Growth

Abstract. This study is based on 18 months (20 July 2006–5 February 2008) of continuous measurements of aerosol particle size distributions, air ion size distributions, trace gas concentrations and basic meteorology in a semi-clean savannah environment in Republic of South Africa. New particle formation and growth was observed on 69% of the days and bursts of non-growing ions/sub-10 nm particles on additional 14% of the days. This new particle formation frequency is the highest reported from boundary layer so far. Also the new particle formation and growth rates were among the highest reported in the literature for continental boundary layer locations; median 10 nm formation rate was 2.2 cm−3 s−1 and median 10–30 nm growth rate 8.9 nm h−1. The median 2 nm ion formation rate was 0.5 cm−3 s−1 and the median ion growth rates were 6.2, 8.0 and 8.1 nm h−1 for size ranges 1.5–3 nm, 3–7 nm and 7–20 nm, respectively. The growth rates had a clear seasonal dependency with minimum during winter and maxima in spring and late summer. The relative contribution of estimated sulphuric acid to the growth rate was decreasing with increasing particle size and could explain more than 20% of the observed growth rate only for the 1.5–3 nm size range. Also the air mass history analysis indicated the highest formation and growth rates to be associated with the area of highest VOC (Volatile Organic Compounds) emissions following from biological activity rather than the highest estimated sulphuric acid concentrations. The frequency of new particle formation, however, increased nearly monotonously with the estimated sulphuric acid reaching 100% at H2SO4 concentration of 6 · 107 cm−3, which suggests the formation and growth to be independent of each other.

scholarly journals Critical cluster composition from homogeneous nucleation data: application to water in carbon dioxide–nitrogen carrier gases

2021 ◽  
Vol 62 (9) ◽  
Author(s):  
M. M. Campagna ◽  
J. Hrubý ◽  
M. E. H. van Dongen ◽  
D. M. J. Smeulders
Keyword(s):  
Carbon Dioxide ◽  
Nucleation Rate ◽  
Molar Fraction ◽  
Nucleation Theory ◽  
Critical Cluster ◽  
Data Application ◽  
Cluster Composition ◽  
Carrier Gases ◽  
Nucleation Theorem ◽  
First Time

AbstractKnowledge on critical cluster composition is important for improving the nucleation theory. Thus, homogeneous water nucleation experiments previously carried out in nitrogen and 0%, 5%, 15% and 25% of carbon dioxide ( Campagna et al. 2020a, 2021) are analyzed. The tests were conducted at 240 K and 0.1 MPa, 1 MPa and 2 MPa. The observed nucleation rates are strongly dependent on supersaturation, pressure, temperature and mixture composition. These experimentally found dependencies can be used to derive the composition of critical clusters by means of the nucleation theorem. In this way, a macroscopic quantity, nucleation rate, reveals properties of critical clusters consisting of a few tens of molecules. Two novel methods are presented for the detailed application of the nucleation theorem. The first method extends to mixtures of $$\,\,\,\,\,\,\,N>2\,\,\,\,\,\,$$ N > 2 components the approach used in literature for two components. The second method not only applies to $$N>2$$ N > 2 mixtures in a more straightforward manner, but it can also be used for unary as well as for binary and multi-component nucleation cases. To the best of our knowledge, for the first time the critical cluster composition is computed for high pressure nucleation data of a vapor (here water) in mixtures of two carrier gases (here carbon dioxide–nitrogen). After a proper parameterization of the nucleation rate data, both methods consistently lead to the same critical nuclei compositions within the experimental uncertainty. Increasing pressure and carbon dioxide molar fraction at fixed supersaturation leads to a decrease in the water content of the critical cluster, while the adsorbed number of nitrogen and carbon dioxide molecules increases. As a consequence, the surface tension decreases. This outcome explains the observed increase in the nucleation rate with increasing pressure and carbon dioxide molar fraction at constant supersaturation. Graphic abstract

scholarly journals Growth of sulphuric acid nanoparticles under wet and dry conditions

2014 ◽  
Vol 14 (12) ◽  
pp. 6461-6475 ◽  
Author(s):  
L. Skrabalova ◽  
D. Brus ◽  
T. Anttila ◽  
V. Zdimal ◽  
H. Lihavainen
Keyword(s):  
Relative Humidity ◽  
Sulphuric Acid ◽  
Ammonium Sulphate ◽  
Residence Time ◽  
Growth Rates ◽  
Initial Growth ◽  
Flow Tube ◽  
H2so4 Concentration ◽  
Wall Losses ◽  
Dry Conditions

Abstract. New particle formation, which greatly influences the number concentrations and size distributions of an atmospheric aerosol, is often followed by a rapid growth of freshly formed particles. The initial growth of newly formed aerosol is the crucial process determining the fraction of nucleated particles growing to cloud condensation nuclei sizes, which have a significant influence on climate. In this study, we report the laboratory observations of the growth of nanoparticles produced by nucleation of H2SO4 and water in a laminar flow tube at temperatures of 283, 293 and 303 K, under dry (a relative humidity of 1%) and wet conditions (relative humidity of 30%) and residence times of 30, 45, 60 and 90 s. The initial H2SO4 concentration spans the range from 2 × 108 to 1.4 × 1010 molecule cm−3 and the calculated wall losses of H2SO4 were assumed to be diffusion limited. The detected particle number concentrations, measured by the Ultrafine Condensation Particle Counter (UCPC) and Differential Mobility Particle Sizer (DMPS), were found to depend strongly on the residence time. Hygroscopic particle growth, presented by growth factors, was found to be in good agreement with the previously reported studies. The experimental growth rates ranged from 20 nm h−1 to 890 nm h−1 at relative humidity (RH) 1% and from 7 nm h−1 to 980 nm h−1 at RH 30% and were found to increase significantly with the increasing concentration of H2SO4. Increases in the nucleation temperature had a slight enhancing effect on the growth rates under dry conditions. The influence of relative humidity on growth was not consistent – at lower H2SO4 concentrations, the growth rates were higher under dry conditions while at H2SO4 concentrations greater than 1 × 1010 molecule cm−3, the growth rates were higher under wet conditions. The growth rates show only a weak dependence on the residence time. The experimental observations were compared with predictions made using a numerical model, which investigates the growth of particles with three different extents of neutralization by ammonia, NH3: (1) pure H2SO4 – H2O particles; (2) particles formed by ammonium bisulphate, (NH4)HSO4; (3) particles formed by ammonium sulphate, (NH4)2SO4. The highest growth rates were found for ammonium sulphate particles. Since the model accounting for the initial H2SO4 concentration predicted the experimental growth rates correctly, our results suggest that the commonly presumed diffusional wall losses of H2SO4 in case of long-lasting experiments are not so significant. We therefore assume that there are not only losses of H2SO4 on the wall, but also a flux of H2SO4 molecules from the wall into the flow tube, the effect being more profound under dry conditions and at higher temperatures of the tube wall. Based on a comparison with the atmospheric observations, our results indicate that sulphuric acid alone cannot explain the growth rates of particles formed in the atmosphere.

scholarly journals Experimental study of H<sub>2</sub>SO<sub>4</sub> aerosol nucleation at high ionization levels

2017 ◽  
Author(s):  
Maja Tomicic ◽  
Martin Bødker Enghoff ◽  
Henrik Svensmark
Keyword(s):  
Sulphuric Acid ◽  
Cluster Size ◽  
Gamma Ray ◽  
Reaction Chamber ◽  
Critical Cluster ◽  
H2so4 Concentration ◽  
Ion Concentrations ◽  
High Ionization ◽  
Direct Measurements ◽  
Mobility Diameter

Abstract. One hundred and ten direct measurements of aerosol nucleation rate at high ionization levels were performed in an 8 m3 reaction chamber. Neutral and ion-induced particle formation from sulphuric acid (H2SO4) as a function of ionization and H2SO4 concentration was studied. Other species that could participate in the nucleation were not measured. The measurements extend the parameter space of measurements described by (Dunne, 2016) (at T = 295 K and RH = 38 %) by expanding to lower H2SO4 concentrations (4x106–3x107 cm−3) and higher ion concentrations (1700–19000 cm−3). The ion concentrations, which correspond to levels caused by a nearby supernova, were achieved with gamma ray sources. Nucleation rates were directly measured with a particle size magnifier (PSM Airmodus A10) at a size close to critical cluster size (mobility diameter of ~ 1.4 nm) and formation rates at mobility diameter of ~ 4 nm were measured with a CPC (TSI model 3775). The measurements show that nucleation increases by around a factor of five when the ionization increases from background to supernova levels under fixed gas conditions. The results expand the parametrization from (Dunne, 2016) to lower sulphuric acid concentrations and higher ion concentrations.

Factors influencing the mode of thermal decomposition of zirconium sulphate tetrahydrate

1967 ◽  
Vol 20 (3) ◽  
pp. 415 ◽  
Author(s):  
IJ Bear
Keyword(s):  
Thermal Decomposition ◽  
Particle Size ◽  
Sulphuric Acid ◽  
Vapour Pressure ◽  
Thermal Decomposition Process ◽  
Monoclinic Zro2 ◽  
X Ray ◽  
Factors Influencing ◽  
Diffraction Patterns ◽  
Hydrolysis Of

The thermal decomposition process of zirconium sulphate tetrahydrate has been studied. Dehydration, which takes place via a crystalline monohydrate phase, is accompanied by the loss of small amounts of sulphuric acid apparently resulting from internal hydrolysis of the compound. This process gives a non-stoicheiometric zirconium sulphate which may exist in several modifications depending on the vapour pressure of the sulphuric acid around the sample during dehydration. The vapour pressure of the sulphuric acid is in turn controlled by such factors as the particle size of the tetrahydrate preparation, the size of sample, and the temperature and technique used during heating. Equilibration experiments have shown that a-Zr(SO4)2 is the stable anhydrous form. The X-ray powder diffraction patterns of a- and γ- Zr(SO4)2 have been indexed. Above 650� all forms of Zr(SO4)2 decompose to cubic ZrO2 which transforms to monoclinic ZrO2 at 800�.

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