A Computationally Efficient Aerosol Nucleation/ Condensation Method: Pseudo-Steady-State Sulfuric Acid

In order to model accurately the size and number of atmospheric particles, it is necessary to predict aerosol nucleation rates. However, the explicit prediction of the sulfuric acid vapor concentration may become computationally intensive when nucleation and condensation are simultaneously occurring. In this article, we develop and test a computationally efficient solution to the problem of solving for the sulfuric acid vapor concentration. Rather than explicitly solving the differential equation for the temporal profile of sulfuric acid vapor, we assume that the sulfuric acid vapor is at the concentration in steady state with its source (oxidation of SO₂) and sinks (condensation and nucleation); this is known as the Pseudo-Steady-State Approximation (PSSA). Two versions of a box model with online size-resolved aerosol microphysics were developed to test the PSSA; (1) a “benchmark model” that solves explicitly for the sulfuric acid vapor concentration, and (2) a “PSSA model” that uses the PSSA. A wide array of atmospheric conditions was used to compare the benchmark and PSSA models. The mean difference in the total number of particles in the two models with diameters larger than 10 nm was only 1.8% and 1.1% in lower troposphere simulations after 2 and 6 hours, and 3.8% and 2.3% in the upper troposphere simulations after 2 and 6 h. The PSSA model was faster in 97% of the tests, more than ten times faster in 91% of the points, and more than 100 times faster in 69% of the tests.     

Enhanced Reactive Uptake of Nonanal by Acidic Aerosols in the Presence of Particle-Phase Organics

An electrodynamic balance was used to examine the effect of the presence of particle-phase organics on the acid-catalyzed reactive uptake of nonanal (NL) vapor. Uptake experiments were conducted by using sulfuric acid (SA) particles, oleic acid/SA (hydrophobic), and levoglucosan/SA (hydrophilic) mixed particles with 6 ppm (approximately) gas-phase NL at about 3% relative humidity. SA reacted with the mixed organics prior to NL uptake to form organic products, denoted as OleA* and Levo*, and with NL to form hydrophobic NL* (particle-phase organics). Fresh SA particles had small mass increases (5%–13%) at the start of NL exposure (0–40 min) even though they are highly acidic. However, OleA*/SA mixed particles of about 30–70 wt% of OleA* took up NL swiftly during the first 40 min. For example, the mass increase of a 33 wt% OleA* particle jumped to 120%. As the organic product, NL*, accumulated, the uptake rate of SA particle increased and the mass increase surged to 150% at 100 min. Afterwards, the mass increase started to level off which yielded a sigmoid uptake curve. For OleA*/SA particles, the uptake rate gradually slowed down resulting in physical-absorption-like uptake kinetics. The physical uptake of NL by a pure OleA* surrogate was negligible (<1%) showing that the large uptake of OleA*/SA particles were attributed to the enhanced reactive uptake of NL in the presence of hydrophobic OleA*. Conversely, the hydrophilic Levo*/SA particles were incompatible with NL, and they showed insignificant enhanced uptake compared with the SA particles. Overall, the acidic uptake of NL is highly dependent on the chemical nature and weight percentages of particle-phase organics in mixed particles. Presence of hydrophobic organic materials in particles enhanced the reactive uptake of NL.     

Measuring Ambient Acidic Ultrafine Particles Using Iron Nanofilm Detectors: Method Development

The number concentration and size-resolved properties of acidic ultrafine particles have been observed to more closely associate with adverse health effects than do indices of total particulate mass. However, no reliable measurement techniques are currently available to quantify the number concentration and the size distribution of ambient acidic ultrafine particles. In this study, a method with the use of iron nanofilm detectors for enumeration and size measurement of acid aerosols is developed and refined. Standard sulfuric acid (H₂SO₄) or ammonium hydrogen sulfate (NH₄HSO₄) droplets and sulfuric acid-coated particles were generated and deposited on the detectors causing reaction spots. The dimensions of the reaction spots were examined with Atomic Force Microscopy (AFM) to establish the correlations between the diameter of the particle and the size of the reaction spot. To validate this method, field measurements were conducted from September 06 to November 30, 2010, at Tai Mo Shan in Hong Kong. The results indicated that the particle number concentrations obtained from the AFM scanning of the exposed detectors via scanning mobility particle sizer (SMPS) and electrostatic precipitator (ESP) collection were comparable to those derived from the SMPS + CPC (condensation particle counter) measurements (p > 0.05). The average geometric mean diameter of particles at peak measured by the SMPS + CPC and the detectors scanned by the AFM was 52.3 ± 6.9 nm and 51.9 ± 3.1 nm, respectively, showing good agreement. It is suggested that the iron nanofilm detectors could be a reliable tool for the measurement and analysis of acidic particles in the atmosphere.

Copyright 2012 American Association for Aerosol Research     

Water Uptake by NaCl Particles Prior to Deliquescence and the Phase Rule

Using an environmental transmission electron microscope (ETEM), we show that a significant amount of water, far exceeding the multilayers caused by surface adsorption, is reversibly associated prior to deliquescence with substrate-supported NaCl particles (dry diameters of ～ 40 nm to 1.5 μ m; ～ 18°C). We hypothesize that the water is present as an aqueous solution containing dissolved Na and Cl ions. Water uptake occurs at relative humidities (RH) as low as 70%, and the resulting liquid layer coating the particles is stable over extended times if the RH is held constant. We exposed CaSO ₄ and CaSO ₄ · 2H ₂ O particles to elevated RH values in the ETEM to show that chemically nonspecific condensation of gas-phase water on the TEM substrate does not explain our observations. Furthermore, damage to the NaCl surface induced by the electron beam and small fluctuations in RH do not seem to contribute to or otherwise affect water uptake. We have similar observations of water association for other alkali halide particles, including NaBr and CsCl, prior to deliquescence. To explain the observations, we derive the phase rule for this geometry and show that it allows for the coexistence of liquid, solid, and vapor for the binary NaCl/H ₂ O system across a range of RH values. The derivation includes the effects of heterogeneous pressure because of the Laplace-Young relations for the subsystems. Furthermore, in view of the lever rule and the absence of similar observations for free-floating pure NaCl aerosol particles, we hypothesize that the surface energy necessary to support these effects is provided by sample-substrate interactions. Thus, the results of this study may be relevant to atmospheric systems in which soluble compounds are associated with insoluble materials.     

Size resolved chemical composition of nanoparticles from reactions of sulfuric acid with ammonia and dimethylamine

Abstract

Nanoparticle formation and growth driven by acid-base chemistry was investigated by introducing gas-phase sulfuric acid (H₂SO₄) with ammonia (NH₃) or dimethylamine (DMA) into a flow tube reactor. A thermal desorption chemical Ionization mass spectrometer was used to measure the size-resolved chemical composition of H₂SO₄-DMA and H₂SO₄- NH₃ nanoparticles formed under dry conditions and at 60% relative humidity. In contrast with predictions for bulk aqueous systems, nanoparticles showed a strong size-dependent composition gradient and did not always reach a fully neutralized state in excess of gas-phase base. Smaller particles were more acidic, with an acid:base ratio of 0.7?±?0.1 and 1.3?±?0.3 for 8.6 and 9.5?nm H₂SO₄-DMA particles formed under dry and humid conditions, respectively, and 3.1?±?0.6 and 3.4?±?0.3 for 7.5?nm H₂SO₄-NH₃ particles formed under dry and humid conditions, respectively. The acidity of particles generally decreased as particles grew. H₂SO₄-DMA particles became fully neutralized as they grew to 14?nm, but H₂SO₄-NH₃ particles at 12?nm were still acidic and were never observed to reach bulk sample thermodynamic equilibrium for the experimental conditions in this study. Thermodynamic modeling demonstrated that the observed trends can be reproduced by modifying acid dissociation constants to minimize acid-base chemistry, which may be caused by steric or mixing effects, and by considering volatilization of the neutral base.

Copyright © 2018 American Association for Aerosol Research     

Nitration of nitrobenzene at high‐concentrations of sulfuric acid: Mass transfer and kinetic aspects

This article reports studies on mass transfer and kinetics of nitration of nitrobenzene at high concentrations of sulfuric acid in a batch reactor at different temperatures. The effects of concentration of sulfuric acid, speed of stirring, and temperature on mass transfer coefficient were investigated. The kinetics of nitration under homogenized conditions was studied at different sulfuric acid concentrations at these temperatures. The reaction rate constants were determined. The variation of rate constant with sulfuric acid concentration was explained by the M_c function. The activation energies of the reactions were determined from the Arrhenius plots. The regimes of the reactions were determined using the values of the mass transfer coefficients and the reaction rate constants. A model was developed for simultaneous mass transfer and chemical reaction in the aqueous phase. The yields of the three isomers of dinitrobenzene were determined, and the variation of isomer distribution with sulfuric acid concentration and temperature was analyzed. This work demonstrates that more than 90% conversion of nitrobenzene is possible at high‐sulfuric acid concentrations resulting in high yield of the product even at moderate temperatures and at low speeds of stirring. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Vergleich des Stofftransports von hängenden und akustisch levitierten Wassertropfen in CO2

High‐pressure acoustic levitation devices allows a contact‐free investigation of liquids. Here, acoustically levitated water droplets and pendant water droplets were examined in regards to the mass transfer coefficient in a static CO₂‐atmosphere under elevated pressures. Based on the droplet geometry and the decrease of the droplet volume over time, it was possible to calculate the mass transfer coefficient of water into CO₂ at any given time. Additionally, open questions regarding possible differences between pendant and acoustically levitated water droplets were discussed.     

Characterization of a bipolar near-infrared laser desorption/ionization aerosol mass spectrometer

A novel method of soft ionization aerosol mass spectrometry (AMS), bipolar near-infrared laser desorption/ionization AMS (BP-NIR-LDI-AMS), has been developed for the on-line, real-time analysis of organic aerosols. Use of a single NIR laser pulse to desorb/ionize aerosols deposited onto an aluminum probe results in minimal analyte fragmentation to produce exclusively intact pseudomolecular ions at [M–H]^? for acidic organic analytes and [M+H]⁺ for basic organic analytes. Incorporation of a bipolar mass spectrometer with the NIR-LDI source enables simultaneous detection of acidic and basic species in organic particles. Limits of detection (total particulate mass sampled) for amino acids common to the organic fraction of atmospheric aerosols ranged from 69.1 pg for ornithine to 197 pg for serine on the positive channel, and from 17.0 pg for glycine to 100 pg for ornithine on the negative channel. From studies of the laser energy dependence of the NIR-LDI mechanism, it was found that [M–H]^? formation for oleic acid proceeds through simultaneous action of two 1064 nm photons, suggesting a surface-assisted process rather than direct photoionization, for which photon energy is insufficient. For acidic aerosol species, sensitivity was found to increase as a function of analyte acidity, while for basic species, [M+H]⁺ ion signals were detected only in the presence of a labile proton source, with the intensity of the ion signals scaling with the acidity of the proton source. The sensitivity of BP-NIR-LDI-AMS to the amino acids was rationalized in terms of their acidic/basic character, as measured by isoelectric point (pI), with the cationic sensitivity scaling proportionally with pI and the anionic sensitivity scaling inversely with pI.

© 2016 American Association for Aerosol Research     

Thermodynamic modeling of HNO3‐H2SO4‐H2O ternary system with symmetric electrolyte NRTL model

The nitric acid concentration/sulfuric acid concentration (NAC/SAC) process has been widely used for concentrating dilute aqueous nitric acid and recovering spent sulfuric acid. Dilute nitric acid (65 to 80 wt %) is concentrated using sulfuric acid to bind water and break the nitric acid‐water azeotrope at approximately 68 wt % nitric acid. To support heat and mass balance calculations and process simulation for NAC/SAC processes, we develop a comprehensive thermodynamic model for nitric acid‐sulfuric acid‐water ternary system based on previously published thermodynamic models of nitric acid‐water and sulfuric acid‐water binary systems with eNRTL equation. The ternary system model correlates well the isobaric vapor‐liquid equilibrium data at one atmosphere and the water and nitric acid activities data at 273.15 K for the ternary. Contour plots of boiling points, vapor phase composition, and specific heat capacity of the ternary system, as well as a Merkel enthalpy‐concentration chart are generated for engineering use. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3110–3117, 2017     

Effect of preparation method on the acidities of Al-B-O x mixed oxides

A series of Al-B-O _x metal oxides with various Al/B ratios were prepared with impregnation and coprecipitation methods. The surface acidic properties of these catalysts were examined by temperature-programmed desorption (TPD) of ammonia and the dehydration reaction of isopropanol. The dehydration reaction was carried out in a continuous-flow microreactor at 130–260 °C under atmospheric pressure. The results of TPD of ammonia indicated that the surface acidity of Al-B-O _x material is medium-strong. The acidic strengths are approximately the same for all the Al-B-O _x samples, regardless of its preparation method. In addition, their acid strengths are much stronger than that of pure alumina. However, the acid concentration is increased with decreasing the Al/B atomic ratio of the catalyst. The dehydration activities of these catalysts are increased with decreasing the Al/B atomic ratios of the samples. The results also indicated that the addition of boron on alumina, no matter what preparation method is used, could significantly enhance the acidities of the catalysts. A compensation effect was observed in isopropanol dehydration reaction over these catalysts. The preexponential factor decreases and activation energy increases with increasing Al/B ratio of the catalyst. The results can be interpreted in terms of the acidity of the catalyst.     

Diffusion-Limited Versus Quasi-Equilibrium Aerosol Growth

Condensation of gas-phase material onto particulate matter is the predominant route by which atmospheric aerosols evolve. The traditional approach to representing formation of secondary organic aerosols (SOAs) is to assume instantaneous partitioning equilibrium of semivolatile organic compounds between gas and particle phases. Growth occurs as the vapor concentration of the species increases owing to gas-phase chemistry. The fundamental mathematical basis of such a condensation growth mechanism (quasi-equilibrium growth) has been lacking. Analytical solutions for the evolution of an organic aerosol size distribution undergoing quasi-equilibrium growth and irreversible diffusion-limited growth are obtained for open and closed systems. The quasi-equilibrium growth emerges as a limiting case for semivolatile species condensation when the rate of change of the ambient vapor concentration is slow compared with the rate of establishment of local gas-aerosol equilibrium. The results suggest that the growth mechanism in a particular situation might be inferred from the characteristics of the evolving size distribution. In certain conditions, a bimodal size distribution can occur during the condensation of a single species on an initially unimodal distribution.

Copyright 2012 American Association for Aerosol Research     

Collection and Generation of Sulfuric Acid Aerosols in a Wet Electrostatic Precipitator

Wet electrostatic precipitators (WESPs) are considered to be a possible technology for the control of sulfuric acid mist. The performance of a lab-scale WESP was investigated as a precipitator for sulfuric acid aerosol droplets produced under controlled conditions in a pilot plant. It was found that for higher levels of residual SO₂ in the flue gas, WESP collection efficiencies were greatly reduced due to aerosol formation inside the WESP. Investigations showed a strong correlation of aerosol emission from the WESP with incoming SO₂ concentration and operating voltage. It is suspected that the reactive species produced in the nonthermal plasma of the corona discharge oxidize the SO₂ to SO₃ which forms sulfuric acid. This causes supersaturation with subsequent homogeneous nucleation and thus aerosol formation.

Copyright 2015 American Association for Aerosol Research     

Utilization of spent petrochemical sulfuric acid in the production of wet‐process phosphoric acid

The possibility of the application of spent sulfuric acid from the petrochemical industry in wet‐process phosphoric acid technology was investigated. The effect of organic impurities in sulfuric acid from benzol acidic refining on the solubility of calcium sulfate hydrates is discussed. Solubility isotherms and regression equations for CaSO₄–H₃PO₄–H₂SO₄–H₂O (pure and containing impurities) systems are presented. Phase transition temperatures between dihydrate and hemihydrate calcium sulfate were determined. The difference between pure and polluted sulfuric acid systems observed is negligible over the range of typical wet‐process phosphoric acid technology parameters. It is concluded that the application of spent sulfuric acid from benzol acidic refining does not have a negative influence on the crystallization process of dihydrate calcium sulfate and therefore can be applied in wet‐process phosphoric acid technology. Copyright © 2005 Society of Chemical Industry     

Parameterization for Atmospheric New-Particle Formation: Application to a System Involving Sulfuric Acid and Condensable Water-Soluble Organic Vapors

A new parameterization for atmospheric new-particle formation has been developed. The parameterization takes into account the early growth of nucleated clusters by condensation of sulfuric acid and water-soluble organic vapors, as well as the scavenging of the growing nuclei by coagulation into larger pre-existing particles. The main input parameters are the nucleation rate, the concentration of sulfuric acid and organic vapor(s) contributing to the nuclei growth, and the pre-existing particle size distribution. The resulting output quantity is the formation rate of particles at a desired size, typically a few nanometers of particle diameter. Comparisons to detailed numerical simulations demonstrated that the parameterization is relatively accurate when the nucleation rate, condensable vapor concentrations, and nuclei growth rate change sufficiently slowly with time, and when the nucleation rate is not very high. As such, the parameterization is most applicable to“regional nucleation events,”in which new-particle formation occurs over distances of tens to hundreds of kilometers. The main obstacle in applying the new parameterization is that organic vapors contributing to the early growth of nucleated clusters have not been identified so far. A couple of solutions to this problem are proposed.     

Separation of Zinc Ions from an Acidic Mine Drainage using a Stirred Transfer Cell–Type Emulsion Liquid Membrane Contactor

Abstract

This is a report on the separation and recovery of zinc ions from an acidic mine drainage using a stirred transfer cell‐type emulsion liquid membrane contactor. Di(2‐ethylhexyl) phosphoric acid was used as a highly selective carrier for the transport of zinc ions through the emulsified liquid membrane. A study was made of the effect on the extraction extent and initial extraction rate of the following variables: pH and initial metal concentration of the feed phase, carrier content in the organic solution, a stripping agent concentration in the receiving phase, and stirring speed in the transfer cell. The content of sulfuric acid as a stripping agent did not show in the studied range any significant influence on metal permeation through the SLM, although a minimum hydrogen ion concentration of 100 g/L is suggested in the internal aqueous solution to ensure an acidity gradient between both aqueous phases to promote the permeation of metal ions toward the strip liquor. Results show that using a pH of 4.0 in the feed acid solution, a concentration of 3% w/w_o of phosphoric carrier in the organic phase and a H₂SO₄ content of 100 g/L in the strip liquor, the extent and rate of extraction through the liquid membrane can be highly favored, pointing to the potential of this method for extracting heavy metals from many kinds of dilute aqueous solutions.     

Heterogeneous Reactions of Chlorine Nitrate and Dinitrogen Pentoxide on Sulfuric Acid Surfaces Representative of Global Stratospheric Aerosol Particles

Increasing evidence from field measurements, modeling studies, and laboratory experiments suggests that heterogeneous reactions on stratospheric sulfate aerosol particles can change the partitioning in the nitrogen and chlorine families and thereby affect global ozone levels. In this study, a Knudsen cell flow reactor was used to measure the uptake of ClONO₂ and N₂O₅ by sulfuric acid solutions representative of background and volcanic stratospheric aerosol particles. The uptake coefficient (γ) of chlorine nitrate on 50–75 wt% H₂SO₄ at 223 K was found to be markedly dependent on the acid concentration, with γ ranging from about 1 × 10⁻² to 1 × 10⁻⁴. These results are in good agreement with literature reports and the data fit the expression log γ= 1.87 – 0.074 × (wt% H₂SO₄). This reaction will thus have its largest impact when stratospheric temperatures are low and sulfuric acid aerosols are most dilute. Uptake of N₂O₅ was studied on solutions with compositions in the range 58–96 wt% H₂SO₄ at temperatures from 193 to 303 K. N₂O₅ reacted readily on sulfuric acid surfaces with uptake coefficients of about 0.06. The uptake coefficient was found to be independent of the sulfuric acid concentration and the solution temperature over the ranges studied. These results suggest that the reaction of N₂O₅ with H₂O will occur readily on sulfuric acid aerosol particles for most stratospheric conditions.     

Hygroscopic Growth of an (NH 4 ) 2 SO 4 Aqueous Solution Droplet Measured Using an Environmental Scanning Electron Microscope (ESEM)

The contact angle, θ, and volume equivalent diameter of an (NH₄)₂SO₄ aqueous droplet was measured using an environmental scanning electric microscope (ESEM), showing the hygroscopic growth of the solution droplet as the relative humidity (RH) increased from 80% to 98%. (NH₄)₂SO₄ particles with diameters in the range 1–2 μ m were produced by an atomization technique, and collected onto a copper substrate that had been treated with polytetrafluoroethylene. To observe the hygroscope growth, the sample chamber of the ESEM was filled with water vapor at a pressure of 600 Pa, and the sample temperature was adjusted using a cooling stage to control the relative humidity inside the chamber. Before the observation of the hygroscopic growth, we determined the value of θ from overhead views of droplets on the stage at a tilted angle of 45°. The average value of θ was 96 ± 10°, and this value was used to estimate the droplet diameter. We measured the diameter of the (NH₄)₂SO₄ droplets at different RH, and observed that the growth factor, G, increased with increasing RH. The experimental value of G was consistent with the theoretically estimated value. This shows that our method for determining the value of θ was valid, and that the ESEM technique can be used to measure the diameters of droplets of aqueous solutions.     

Modeling the thermodynamics and kinetics of sulfuric acid-dimethylamine-water nanoparticle growth in the CLOUD chamber

Dimethylamine (DMA) has a stabilizing effect on sulfuric acid (SA) clusters, and the SA and DMA molecules and clusters likely play important roles in both aerosol particle formation and growth in the atmosphere. We use the monodisperse particle growth model for acid-base chemistry in nanoparticle growth (MABNAG) together with direct and indirect observations from the CLOUD4 and CLOUD7 experiments in the cosmics leaving outdoor droplets (CLOUD) chamber at CERN to investigate the size and composition evolution of freshly formed particles consisting of SA, DMA, and water as they grow to 20 nm in dry diameter. Hygroscopic growth factors are measured using a nano-hygroscopicity tandem differential mobility analyzer (nano-HTDMA), which combined with simulations of particle water uptake using the thermodynamic extended-aerosol inorganics model (E-AIM) constrain the chemical composition. MABNAG predicts a particle-phase ratio between DMA and SA molecules of 1.1–1.3 for a 2 nm particle and DMA gas-phase mixing ratios between 3.5 and 80 pptv. These ratios agree well with observations by an atmospheric-pressure interface time-of-flight (APi-TOF) mass spectrometer. Simulations with MABNAG, direct observations of the composition of clusters <2 nm, and indirect observations of the particle composition indicate that the acidity of the nucleated particles decreases as they grow from ～1 to 20 nm. However, MABNAG predicts less acidic particles than suggested by the indirect estimates at 10 nm diameter using the nano-HTDMA measurements, and less acidic particles than observed by a thermal desorption chemical ionization mass spectrometer (TDCIMS) at 10–30 nm. Possible explanations for these discrepancies are discussed.

Copyright © 2016 American Association for Aerosol Research     

Catalytic dehydration of glycerol to acrolein over sulfuric acid-activated montmorillonite catalysts

For the development of efficient solid acid catalysts for the catalytic dehydration of glycerol to acrolein, catalysts made from montmorillonitic clay activated by sulfuric acid were investigated. Montmorillonite was activated in diluted sulfuric acid in the concentration range of 5–40 wt.%. The effects of sulfuric acid treatment on the structure of the montmorillonite were characterized by X-ray diffraction, measurements of acidity, N₂ adsorption–desorption isotherms, and Fourier transform infrared spectroscopy. The catalytic behavior of sulfuric acid-activated montmorillonite catalysts in the gas-phase dehydration of glycerol were investigated under varying conditions, including the reaction temperature, the feed rate, and the concentration of glycerol. After montmorillonitic clay was activated by sulfuric acid, the layered structural features of montmorillonite remained nearly intact. Ca^2 +-montmorillonite was changed to H⁺-montmorillonite by ion exchange reaction during activation. The optimal catalytic glycerol dehydration reaction conditions were found to be: temperature at 320 °C, liquid hourly space velocity (LHSV) = 18.5 h^− 1, concentration of glycerol solution = 10 wt.%, and the flow rate of N₂ carrier gas = 10 mL/min. A conversion of 54.2% of glycerol and a yield of 44.9 wt.% acrolein were achieved over the montmorillonite catalyst activated by an aqueous 10 wt.% sulfuric acid solution. The H⁺ in the interlayer space of acid-activated montmorillonite catalysts played a critical role in the catalytic dehydration of glycerol. The temperature, the LHSV, and the concentration of glycerol affected the performance of the catalysts through their influence on the reaction mechanism, the contact time, and the reaction equilibrium.     

Effect of Molecular Structure and Hydration on the Uptake of Gas-Phase Sulfuric Acid by Charged Clusters/Ultrafine Particles

The enhanced uptake of sulfuric acid molecules by charged clusters as a result of dipole–charge interaction is critical to the ion-mediated nucleation of particles in the atmosphere. This article illustrates the effect of the structure of the gas-phase sulfuric acid and its hydrates on the uptake of the sulfuric acid molecules by the charged clusters/ultrafine particles. It is shown that the different structures of gas-phase sulfuric acid and its hydrates lead to very big (up to ～ 230%) variations in the uptake coefficients due to the large difference in the dipole moments. On average, the hydration of gaseous sulfuric acid in the atmosphere is likely to enhance the uptake coefficients.