scholarly journals Effect of mixing structure on the water uptake of mixtures of ammonium sulfate and phthalic acid particles

2020 ◽  
Author(s):  
Weigang Wang ◽  
Ting Lei ◽  
Andreas Zuend ◽  
Hang Su ◽  
Yafang Cheng ◽  
...  
Keyword(s):  
Growth Factor ◽  
Relative Humidity ◽  
Ammonium Sulfate ◽  
Water Uptake ◽  
Phthalic Acid ◽  
Core Shell ◽  
Hygroscopic Growth ◽  
The Core ◽  
Mass Fractions ◽  
Shell Particles

Abstract. Aerosol mixing state regulates the interactions between water molecules and particles and thus controls the aerosol activation and hygroscopic growth, which thereby influences the visibility degradation, cloud formation, and its radiative forcing. Current studies on the mixing structure effects on aerosol hygroscopicity, however, is few reported. Here we investigated the effect of phthalic acid (PA) coatings on the hygroscopic behavior of the core-shell mixtures of ammonium sulfate (AS) with PA using a coating-hygroscopicity tandem differential mobility analyzer (coating-HTDMA). The slow increase in the hygroscopic growth factor of core-shell particles is observed with increasing thickness of coating PA prior to the DRH of AS. At RH above 80 %, a decrease in hygroscopic growth factor of particles occurs as the thickness of PA shell increases, which indicates that the increase of PA mass fractions leads to a reduction of the overall core-shell particle hygroscopicity. In addition, the use of the ZSR relation leads to the underestimation for the measured growth factors of core-shell particles without consideration of the morphological effect of core-shell particles. For the AS/PA well mixed particles, a shift of deliquescence relative humidity (DRH) of AS to lower relative humidity (RH) is observed due to the presence of PA in the well-mixed particles. The predicted hygroscopic growth factor using the ZSR relation is consistent with the measured hygroscopic growth factor of the well-mixed particles. Moreover, we compared and discussed the influence of mixing states on the water uptake of AS/PA aerosol particles. It is found that the hygroscopic growth factor of the core-shell particles is slightly higher than that of the well-mixed particles with the same mass fractions of PA at RH above 80 %. For our observation of AS/PA particles may contribute to a growing field of knowledge regarding the influence of coating properties and mixing structure on water uptake.

scholarly journals Effect of mixing structure on the water uptake of mixtures of ammonium sulfate and phthalic acid particles

2021 ◽  
Vol 21 (3) ◽  
pp. 2179-2190
Author(s):  
Weigang Wang ◽  
Ting Lei ◽  
Andreas Zuend ◽  
Hang Su ◽  
Yafang Cheng ◽  
...  
Keyword(s):  
Growth Factor ◽  
Relative Humidity ◽  
Water Uptake ◽  
Phthalic Acid ◽  
Aerosol Particles ◽  
Core Shell ◽  
Hygroscopic Growth ◽  
The Core ◽  
Mass Fractions ◽  
Mixing States

Abstract. Aerosol mixing state regulates the interactions between water molecules and particles and thus controls aerosol activation and hygroscopic growth, which thereby influences visibility degradation, cloud formation, and its radiative forcing. There are, however, few current studies on the mixing structure effects on aerosol hygroscopicity. Here, we investigated the hygroscopicity of ammonium sulfate / phthalic acid (AS / PA) aerosol particles with different mass fractions of PA in different mixing states in terms of initial particle generation. Firstly, the effect of PA coatings on the hygroscopic behavior of the core-shell-generated mixtures of AS with PA was studied using a coating hygroscopicity tandem differential mobility analyzer (coating HTDMA). The slow increase in the hygroscopic growth factor of core-shell-generated particles is observed with increasing thickness of the coating PA prior to the deliquescence relative humidity (DRH) of AS. At relative humidity (RH) above 80 %, a decrease in the hygroscopic growth factor of particles occurs as the thickness of the PA shell increases, which indicates that the increase of PA mass fractions leads to a reduction of the overall core-shell-generated particle hygroscopicity. In addition, the use of the Zdanovskii–Stokes–Robinson (ZSR) relation leads to the underestimation of the measured growth factors of core-shell-generated particles without consideration of the morphological effect of core-shell-generated particles, especially at higher RH. Secondly, in the case of the AS / PA initially well-mixed particles, a shift of the DRH of AS (∼80 %, Tang and Munkelwitz, 1994) to lower RH is observed due to the presence of PA in the initially well-mixed particles. The predicted hygroscopic growth factor using the ZSR relation is consistent with the measured hygroscopic growth factor of the initially well-mixed particles. Moreover, we compared and discussed the influence of mixing states on the water uptake of AS / PA aerosol particles. It is found that the hygroscopic growth factor of the core-shell-generated particles is slightly higher than that of the initially well-mixed particles with the same mass fractions of PA at RH above 80 %. The observation of AS / PA particles may contribute to a growing field of knowledge regarding the influence of coating properties and mixing structure on water uptake.

scholarly journals Hygroscopicity of organic compounds from biomass burning and their influence on the water uptake of mixed organic ammonium sulfate aerosols

2014 ◽  
Vol 14 (20) ◽  
pp. 11165-11183 ◽  
Author(s):  
T. Lei ◽  
A. Zuend ◽  
W. G. Wang ◽  
Y. H. Zhang ◽  
M. F. Ge
Keyword(s):  
Growth Factors ◽  
Humic Acid ◽  
Ammonium Sulfate ◽  
Organic Compounds ◽  
Water Uptake ◽  
Biomass Burning ◽  
Aerosol Particles ◽  
Hydroxybenzoic Acid ◽  
Hygroscopic Growth ◽  
Mass Fractions

Abstract. Hygroscopic behavior of organic compounds, including levoglucosan, 4-hydroxybenzoic acid, and humic acid, as well as their effects on the hygroscopic properties of ammonium sulfate (AS) in internally mixed particles are studied by a hygroscopicity tandem differential mobility analyzer (HTDMA). The organic compounds used represent pyrolysis products of wood that are emitted from biomass burning sources. It is found that humic acid aerosol particles only slightly take up water, starting at RH (relative humidity) above ~70%. This is contrasted by the continuous water absorption of levoglucosan aerosol particles in the range 5–90% RH. However, no hygroscopic growth is observed for 4-hydroxybenzoic acid aerosol particles. Predicted water uptake using the ideal solution theory, the AIOMFAC model and the E-AIM (with UNIFAC) model are consistent with measured hygroscopic growth factors of levoglucosan. However, the use of these models without consideration of crystalline organic phases is not appropriate to describe the hygroscopicity of organics that do not exhibit continuous water uptake, such as 4-hydroxybenzoic acid and humic acid. Mixed aerosol particles consisting of ammonium sulfate and levoglucosan, 4-hydroxybenzoic acid, or humic acid with different organic mass fractions, take up a reduced amount of water above 80% RH (above AS deliquescence) relative to pure ammonium sulfate aerosol particles of the same mass. Hygroscopic growth of mixtures of ammonium sulfate and levoglucosan with different organic mass fractions agree well with the predictions of the thermodynamic models. Use of the Zdanovskii–Stokes–Robinson (ZSR) relation and AIOMFAC model lead to good agreement with measured growth factors of mixtures of ammonium sulfate with 4-hydroxybenzoic acid assuming an insoluble organic phase. Deviations of model predictions from the HTDMA measurement are mainly due to the occurrence of a microscopical solid phase restructuring at increased humidity (morphology effects), which are not considered in the models. Hygroscopic growth factors of mixed particles containing humic acid are well reproduced by the ZSR relation. Lastly, the organic surrogate compounds represent a selection of some of the most abundant pyrolysis products of biomass burning. The hygroscopic growths of mixtures of the organic surrogate compounds with ammonium sulfate with increasing organics mass fraction representing ambient conditions from the wet to the dry seasonal period in the Amazon basin, exhibit significant water uptake prior to the deliquescence of ammonium sulfate. The measured water absorptions of mixtures of several organic surrogate compounds (including levoglucosan) with ammonium sulfate are close to those of binary mixtures of levoglucosan with ammonium sulfate, indicating that levoglucosan constitutes a major contribution to the aerosol water uptake prior to (and beyond) the deliquescence of ammonium sulfate. Hence, certain hygroscopic organic surrogate compounds can substantially affect the deliquescence point of ammonium sulfate and overall particle water uptake.

scholarly journals Hygroscopic behavior of atmospherically relevant water-soluble carboxylic salts and their influence on the water uptake of ammonium sulfate

2011 ◽  
Vol 11 (24) ◽  
pp. 12617-12626 ◽  
Author(s):  
Z. J. Wu ◽  
A. Nowak ◽  
L. Poulain ◽  
H. Herrmann ◽  
A. Wiedensohler
Keyword(s):  
Relative Humidity ◽  
Ammonium Sulfate ◽  
Water Uptake ◽  
Ammonium Oxalate ◽  
Water Soluble ◽  
Hygroscopic Growth ◽  
Organic Salts ◽  
Deliquescence Relative Humidity ◽  
Hygroscopic Behavior ◽  
Atmospherically Relevant

Abstract. The hygroscopic behavior of atmospherically relevant water-soluble carboxylic salts and their effects on ammonium sulfate were investigated using a hygroscopicity tandem differential mobility analyzer (H-TDMA). No hygroscopic growth is observed for disodium oxalate, while ammonium oxalate shows slight growth (growth factor = 1.05 at 90%). The growth factors at 90% RH for sodium acetate, disodium malonate, disodium succinate, disodium tartrate, diammonium tartrate, sodium pyruvate, disodium maleate, and humic acid sodium salt are 1.79, 1.78, 1.69, 1.54, 1.29, 1.70, 1.78, and 1.19, respectively. The hygroscopic growth of mixtures of organic salts with ammonium sulfate, which are prepared as surrogates of atmospheric aerosols, was determined. A clear shift in deliquescence relative humidity to lower RH with increasing organic mass fraction was observed for these mixtures. Above 80% RH, the contribution to water uptake by the organic salts was close to that of ammonium sulfate for the majority of investigated compounds. The observed hygroscopic growth of the mixed particles at RH above the deliquescence relative humidity of ammonium sulfate agreed well with that predicted using the Zdanovskii-Stokes-Robinson (ZSR) mixing rule. Mixtures of ammonium sulfate with organic salts are more hygroscopic than mixtures with organic acids, indicating that neutralization by gas-phase ammonia and/or association with cations of dicarbonxylic acids may enhance the hygroscopicity of the atmospheric particles.

scholarly journals Hygroscopicity of organic compounds from biomass burning and their influence on the water uptake of mixed organic–ammonium sulfate aerosols

2014 ◽  
Vol 14 (8) ◽  
pp. 11625-11663 ◽  
Author(s):  
T. Lei ◽  
A. Zuend ◽  
W. G. Wang ◽  
Y. H. Zhang ◽  
M. F. Ge
Keyword(s):  
Growth Factors ◽  
Humic Acid ◽  
Ammonium Sulfate ◽  
Organic Compounds ◽  
Water Uptake ◽  
Biomass Burning ◽  
Aerosol Particles ◽  
Hydroxybenzoic Acid ◽  
Hygroscopic Growth ◽  
Mass Fractions

Abstract. Hygroscopic behavior of organic compounds, including levoglucosan, 4-hydroxybenzoic acid and humic acid, and their effects on the hygroscopic properties of ammonium sulfate (AS) in internally mixed particles are studied by a hygroscopicity tandem differential mobility analyzer (HTDMA). The organic compounds used represent pyrolysis products of wood that are emitted from biomass burning sources. It is found that humic acid aerosol particles only slightly take up water, starting at RH above ∼70%. This is contrasted by the continuous water absorption of levoglucosan aerosol particles in the range 5–90% RH. However, no hygroscopic growth is observed for 4-hydroxybenzoic acid aerosol particles. Predicted water uptake using the ideal solution theory, the AIOMFAC model and the E-AIM (with UNIFAC) model are consistent with measured hygroscopic growth factors of levoglucosan. However, the use of these models without consideration of crystalline organic phases is not appropriate to describe the hygroscopicity of organics that do not exhibit continuous water uptake, such as 4-hydroxybenzoic acid and humic acid. Mixed aerosol particles consisting of ammonium sulfate and levoglucosan, 4-hydroxybenzoic acid, or humic acid with different organic mass fractions, take up a reduced amount of water above 80% RH (above AS deliquescence) relative to pure ammonium sulfate aerosol particles of the same mass. Hygroscopic growth of mixtures of ammonium sulfate and levoglucosan with different organic mass fractions agree well with the predictions of the thermodynamic models. Use of the Zdanovskii–Stokes–Robinson (ZSR) relation and AIOMFAC model lead to good agreement with measured growth factors of mixtures of ammonium sulfate with 4-hydrobenxybenzoic acid assuming an insoluble organic phase. Deviations of model predictions from the HTDMA measurement are mainly due to the occurrence of a microscopical solid phase restructuring at increased humidity (morphology effects), which are not considered in the models. Hygroscopic growth factors of mixed particles containing humic acid are well reproduced by the ZSR relation. Lastly, the organic surrogate compounds represent a selection of some of the most abundant pyrolysis products of biomass burning. The hygroscopic growths of mixtures of the organic surrogate compounds with ammonium sulfate with increasing organics mass fraction representing ambient conditions from the wet to the dry seasonal period in the Amazon basin, exhibit significant water uptake prior to the deliquescence of ammonium sulfate. The measured water absorptions of mixtures of several organic surrogate compounds (including levoglucosan) with ammonium sulfate are close to those of binary mixtures of levoglucosan with ammonium sulfate, indicating that levoglucosan constitutes a major contribution to the aerosol water uptake prior to (and beyond) the deliquescence of ammonium sulfate. Hence, certain hygroscopic organic surrogate compounds can substantially affect the deliquescence point of ammonium sulfate and overall particle water uptake.

Magnetic Properties of Fe3O4/CoFe2O4 Composite Nanoparticles with Core/Shell Architecture

2020 ◽  
Vol 65 (10) ◽  
pp. 904
Author(s):  
V. O. Zamorskyi ◽  
Ya. M. Lytvynenko ◽  
A. M. Pogorily ◽  
A. I. Tovstolytkin ◽  
S. O. Solopan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Spinel Ferrite ◽  
Composite Nanoparticles ◽  
Core Shell ◽  
Cofe2o4 Nanoparticles ◽  
Core Diameter ◽  
The Core ◽  
Shell Particles ◽  
Interface Parameters ◽  
Shell Composite

Magnetic properties of the sets of Fe3O4(core)/CoFe2O4(shell) composite nanoparticles with a core diameter of about 6.3 nm and various shell thicknesses (0, 1.0, and 2.5 nm), as well as the mixtures of Fe3O4 and CoFe2O4 nanoparticles taken in the ratios corresponding to the core/shell material contents in the former case, have been studied. The results of magnetic research showed that the coating of magnetic nanoparticles with a shell gives rise to the appearance of two simultaneous effects: the modification of the core/shell interface parameters and the parameter change in both the nanoparticle’s core and shell themselves. As a result, the core/shell particles acquire new characteristics that are inherent neither to Fe3O4 nor to CoFe2O4. The obtained results open the way to the optimization and adaptation of the parameters of the core/shell spinel-ferrite-based nanoparticles for their application in various technological and biomedical domains.

Fe@C core–shell and Fe@C yolk–shell particles for effective removal of 4-chlorophenol

2015 ◽  
Vol 3 (7) ◽  
pp. 3988-3994 ◽  
Author(s):  
Xiang Li ◽  
Fangyuan Gai ◽  
Buyuan Guan ◽  
Ye Zhang ◽  
Yunling Liu ◽  
...  
Keyword(s):  
Carbon Shell ◽  
Core Shell ◽  
The Core ◽  
Effective Removal ◽  
Shell Particles

Fe@C yolk–shell particles were synthesized by reducing the core with its own carbon shell to achieve the effective removal of 4-chlorophenol from water.

Effect of glycidyl methacrylate (GMA) on the stability of acrylic latex

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Guangfeng Wu ◽  
Yue Tao ◽  
Hong Kang ◽  
Huixuan Zhang
Keyword(s):  
Experimental Data ◽  
Glycidyl Methacrylate ◽  
Sodium Dodecyl ◽  
The Other ◽  
Lower Amount ◽  
Core Shell ◽  
Acrylic Latex ◽  
The Core ◽  
Shell Particles ◽  
The Stability

AbstractThe stability of core-shell particles (CSPs) with butyl acrylate (BA) as the core and methyl methacrylate (MMA)/glycidyl methacrylate (GMA) mixture in various compositions as the shell was investigated by turbidity measurements. The experiments demonstrate that lower amount addition of GMA could not improve the latex stability. When the amount of GMA exceeded 2% of the total reactants, it began to improve the stability of the latex. With the increasing content of GMA, the latex became more and more stable. On the other hand, experimental data also show that the stability was improved by increasing the concentration of sodium dodecyl sulfate (SDS).

The Preparation of Core/Shell Particles with Siloxane in the Shell

2005 ◽  
Vol 13 (7) ◽  
pp. 721-726
Author(s):  
Shunsheng Cao ◽  
Xiaobo Deng ◽  
Bailing Liu
Keyword(s):  
Dispersion Medium ◽  
Average Diameter ◽  
Butyl Methacrylate ◽  
Core Shell ◽  
The Core ◽  
Transmission Electron ◽  
Seeding Method ◽  
Emulsion Polymerisation ◽  
Shell Particles ◽  
Methacryloxypropyl Trimethoxysilane

Core-shell microspheres ranging in average diameter from 12.829 to 15.039 μm, with a poly butyl methacrylate (BMA) core, and a poly 3-(methacryloxypropyl)-trimethoxysilane (MATS) shell, were prepared with methanol as the dispersion medium, by a successive seeding method under kinetically controlled conditions. To date, although some of particles (PSi/PA) have been prepared by seeded emulsion polymerisation, only a few core/shell (PA/PSi) microspheres have been reported the literatures. To prepare core/shell (PA/PSi), the core was first synthesized by dispersion polymerisation and to form seeds; addition of MATS monomer was started after 90~95% conversion of the BMA. The reaction was prolonged for another 12 h to achieve complete consumption of MATS monomer. Microspheres; containing hydrophilic PBMA as the core and hydrophobic PMATS as the shell, were successfully formed through the free radical of surface in the core. The particles morphology and size distribution were examined using a Transmission electron microscope and a Malvern Master Sizer/E particle size analyser, respectively.

Influence of Various Reaction Parameters on the Process for Preparation of SiO2/TiO2 Core-Shell Particles

2015 ◽  
Vol 33 ◽  
pp. 27-37 ◽  
Author(s):  
Jhin Hong You ◽  
Yi Yin Kuo ◽  
Keh Ying Hsu
Keyword(s):  
Inorganic Compounds ◽  
Sol Gel ◽  
Chelating Agent ◽  
Condensation Process ◽  
Infrared Analysis ◽  
Ionic Surfactant ◽  
Core Shell ◽  
Reaction Parameters ◽  
The Core ◽  
Shell Particles

This study aims to describe the preparation and characterization of SiO2/TiO2 core-shell particles. In order to prepare the homogenous SiO2/TiO2 inorganic compounds by sol-gel process, SiO2 particles were used as the core, AcAc served as a chelating agent to chelate with TTIP (which was used as the precursor to TiO2), and PEG was added to stabilize the hydrolysis/condensation process. In addition, the ionic surfactant (SDS) and the nonionic surfactant (PVP) dispersed the core-shell particles. In order to improve the crystal structure, a high temperature was used to calcine the core-shell particles. The influence of various reaction parameters on the size, morphology and composition of the particles was also investigated. The properties of the particles were analyzed by electron microscopy, fourier transform infrared analysis, thermogravimetric analysis and powder X-ray diffraction.

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