scholarly journals Utilizing an electrical low-pressure impactor to indirectly probe water uptake via particle bounce measurements

2021 ◽  
Vol 14 (12) ◽  
pp. 7565-7577
Author(s):  
Kevin B. Fischer ◽  
Giuseppe A. Petrucci
Keyword(s):  
Relative Humidity ◽  
Water Uptake ◽  
Geometric Mean ◽  
Complex Viscosity ◽  
Organic Aerosol ◽  
Low Pressure ◽  
Multi Stage ◽  
Volatile Organic ◽  
Particle Bounce ◽  
Phase Behaviors

Abstract. Secondary organic aerosol (SOA), formed through oxidation of volatile organic compounds (VOCs), displays complex viscosity and phase behaviors influenced by temperature, relative humidity (RH), and chemical composition. Here, the efficacy of a multi-stage electrical low-pressure impactor (ELPI) for indirect water uptake measurements was studied for ammonium sulfate (AS) aerosol, sucrose aerosol, and α-pinene-derived SOA. All three aerosol systems were subjected to greater than 90 % chamber relative humidity, with subsequent analysis indicating persistence of particle bounce for sucrose aerosol of 70 nm (initial dry diameter) and α-pinene-derived SOA of number geometric mean diameters between 39 and 136 nm (initial dry diameter). On the other hand, sucrose aerosol of 190 nm (initial dry diameter) and AS aerosol down to 70 nm (initial dry diameter) exhibited no particle bounce at elevated RH. Partial drying of aerosol within the lower diameter ELPI impaction stages, where inherent and significant RH reductions occur, is proposed as one explanation for particle bounce persistence.

scholarly journals Utilizing an Electrical Low Pressure Impactor to Indirectly Probe Water Uptake via Particle Bounce Measurements 

2021 ◽  
Author(s):  
Kevin B. Fischer ◽  
Giuseppe A. Petrucci
Keyword(s):  
Relative Humidity ◽  
Water Uptake ◽  
Geometric Mean ◽  
Complex Viscosity ◽  
Organic Aerosol ◽  
Low Pressure ◽  
Multi Stage ◽  
Volatile Organic ◽  
Particle Bounce ◽  
Phase Behaviors

Abstract. Secondary organic aerosol (SOA), formed through oxidation of volatile organic compounds (VOCs), display complex viscosity and phase behaviors influenced by temperature, relative humidity (RH), and chemical composition. Here, the efficacy of a multi-stage electrical low pressure impactor (ELPI) for indirect water uptake measurements was studied for ammonium sulfate (AS) aerosol, sucrose aerosol, and α-pinene derived SOA. All three aerosol systems were subjected to greater than 90 % chamber relative humidity, with subsequent analysis indicating persistence of particle bounce for sucrose 10 aerosol of 70 nm (initial dry diameter) and α-pinene derived SOA of number geometric mean diameters between 39 nm and 136 nm (initial dry diameter). On the other hand, sucrose aerosol of 190 nm (initial dry diameter) and AS aerosol down to 70 nm (initial dry diameter) exhibited no particle bounce at elevated RH. Partial drying of aerosol within the lower diameter ELPI impaction stages, where inherent and significant RH reductions occur, is proposed as one explanation for particle bounce persistence.

scholarly journals Sensitivities of the absorptive partitioning model of secondary organic aerosol formation to the inclusion of water

2008 ◽  
Vol 8 (6) ◽  
pp. 20311-20348 ◽  
Author(s):  
M. Barley ◽  
D. O. Topping ◽  
G. McFiggans ◽  
M. E. Jenkin
Keyword(s):  
Relative Humidity ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Organic Component ◽  
Condensed Phases ◽  
Aerosol Formation ◽  
Ambient Relative Humidity ◽  
Highly Sensitive ◽  
Volatile Organic ◽  
Secondary Organic Aerosol Formation

Abstract. Depending on the assumptions about the participation of water in absorptive partitioning, the prediction of the distribution of semi-volatile organic component between the gaseous and condensed phases is shown to be highly sensitive to the ambient relative humidity and the formulation of the partitioning model used. Further sensitivities to the assumed pre-existing particulate loading and to parameterised organic component non-ideality are explored and shown to contribute significantly to the variation in predicted secondary organic particulate loading.

scholarly journals Organic particulate matter formation at varying relative humidity using surrogate secondary and primary organic compounds with activity corrections in the condensed phase obtained using a method based on the Wilson equation

2008 ◽  
Vol 8 (1) ◽  
pp. 995-1039 ◽  
Author(s):  
E. I. Chang ◽  
J. F. Pankow
Keyword(s):  
Particulate Matter ◽  
Relative Humidity ◽  
Water Uptake ◽  
Large Scale ◽  
Prediction Method ◽  
Organic Aerosol ◽  
Specific Chemical ◽  
Small Water ◽  
Chemical Structures ◽  
Unifac Model

Abstract. Secondary organic aerosol (SOA) formation in the atmosphere is currently often modeled using a multiple lumped "two-product" (N·2p) approach. The N·2p approach neglects: 1) variation of activity coefficient (ζi) values and mean molecular weight MW in the particulate matter (PM) phase; 2) water uptake into the PM; and 3) the possibility of phase separation in the PM. This study considers these effects by adopting an (N·2p)ζ, MW ,θ approach (θ is a phase index). Specific chemical structures are assigned to 25 lumped SOA compounds and to 15 representative primary organic aerosol (POA) compounds to allow calculation of ζi and MW values. The SOA structure assignments are based on chamber-derived 2p gas/particle partition coefficient values coupled with known effects of structure on vapor pressure pL,i° (atm). To facilitate adoption of the (N·2p)ζ, MW, θ approach in large-scale models, this study also develops CP-Wilson.1, a group-contribution ζi-prediction method that is more computationally economical than the UNIFAC model of Fredenslund et al. (1975). Group parameter values required by CP-Wilson.1 are obtained by fitting ζi values to predictions from UNIFAC. The (N·2p)ζ,MW, θ approach is applied (using CP-Wilson.1) to several real α-pinene/O3 chamber cases for high reacted hydrocarbon levels (ΔHC≈400 to 1000 μg m−3) when relative humidity (RH) ≈50%. Good agreement between the chamber and predicted results is obtained using both the (N·2p)ζ, MW, θ and N·2p approaches, indicating relatively small water effects under these conditions. However, for a hypothetical α-pinene/O3 case at ΔHC=30 μg m−3 and RH=50%, the (N·2p)ζ, MW, θ approach predicts that water uptake will lead to an organic PM level that is more double that predicted by the N·2p approach. Adoption of the (N·2p)ζ, MW, θ approach using reasonable lumped structures for SOA and POA compounds is recommended for ambient PM modeling.

scholarly journals Organic particulate matter formation at varying relative humidity using surrogate secondary and primary organic compounds with activity corrections in the condensed phase obtained using a method based on the Wilson equation

2010 ◽  
Vol 10 (12) ◽  
pp. 5475-5490 ◽  
Author(s):  
E. I. Chang ◽  
J. F. Pankow
Keyword(s):  
Particulate Matter ◽  
Relative Humidity ◽  
Water Uptake ◽  
Large Scale ◽  
Prediction Method ◽  
Organic Aerosol ◽  
Specific Chemical ◽  
Small Water ◽  
Chemical Structures ◽  
Unifac Model

Abstract. Secondary organic aerosol (SOA) formation in the atmosphere is currently often modeled using a multiple lumped "two-product" (N·2p) approach. The N·2p approach neglects: 1) variation of activity coefficient (ζi) values and mean molecular weight MW in the particulate matter (PM) phase; 2) water uptake into the PM; and 3) the possibility of phase separation in the PM. This study considers these effects by adopting an (N·2p)ζpMW,ζ approach (θ is a phase index). Specific chemical structures are assigned to 25 lumped SOA compounds and to 15 representative primary organic aerosol (POA) compounds to allow calculation of ζi and MW values. The SOA structure assignments are based on chamber-derived 2p gas/particle partition coefficient values coupled with known effects of structure on vapor pressure pL,io (atm). To facilitate adoption of the (N·2p)ζpMW,θ approach in large-scale models, this study also develops CP-Wilson.1 (Chang-Pankow-Wilson.1), a group-contribution ζi-prediction method that is more computationally economical than the UNIFAC model of Fredenslund et al. (1975). Group parameter values required by CP-Wilson.1 are obtained by fitting ζi values to predictions from UNIFAC. The (N·2p)ζpMW,θ approach is applied (using CP-Wilson.1) to several real α-pinene/O3 chamber cases for high reacted hydrocarbon levels (ΔHC≈400 to 1000 μg m−3) when relative humidity (RH) ≈50%. Good agreement between the chamber and predicted results is obtained using both the (N·2p)ζpMW,θ and N·2p approaches, indicating relatively small water effects under these conditions. However, for a hypothetical α-pinene/O3 case at ΔHC=30 μg m−3 and RH=50%, the (N·2p)ζpMW,θ approach predicts that water uptake will lead to an organic PM level that is more double that predicted by the N·2p approach. Adoption of the (N·2p)ζpMW,θ approach using reasonable lumped structures for SOA and POA compounds is recommended for ambient PM modeling.

Secondary organic aerosol formation from ethyne in the presence of NaCl in a smog chamber

2016 ◽  
Vol 13 (4) ◽  
pp. 699 ◽  
Author(s):  
Shuangshuang Ge ◽  
Yongfu Xu ◽  
Long Jia
Keyword(s):  
Sodium Chloride ◽  
Relative Humidity ◽  
Nitrogen Oxides ◽  
Secondary Organic Aerosol ◽  
Geometric Mean ◽  
Organic Aerosol ◽  
Photochemical Oxidation ◽  
Smog Chamber ◽  
Aerosol Formation ◽  
Organic Particles

Environmental context Ethyne is the lightest of the non-methane hydrocarbons, whose oxidation product, glyoxal, is an important precursor of secondary organic aerosol. This study explores the effects of relative humidity on the formation of secondary organic aerosol under irradiation in the presence of nitrogen oxides and sodium chloride. Results show that relative humidity can enhance aerosol formation, which provides evidence of the contribution of ethyne to organic particles. Abstract The heterogeneous photochemical oxidation of ethyne was investigated under different relative humidity (RH) conditions in the presence of nitrogen oxides and sodium chloride in a self-made indoor smog chamber. The purpose was to study the influence of RH on the formation of secondary organic aerosol (SOA) from C2H2. Through the experiments, we found that SOA was rarely formed at <22% RH in the presence of NaCl seed particles, and that SOA began to be formed at ≥29% RH in the presence of NaCl, which shows the importance of RH in the formation of SOA. The yield of SOA (YSOA) from C2H2 was 0.2% at 51% RH, and increased by a factor of 17.5 as RH reached 83%. The SOA yield increased with increasing RH. The geometric mean diameter of the particles increased by a factor of 1.17, 1.22, 1.28 and 1.51 at a RH of 51, 63, 74 and 83% respectively at the end of the experiment, indicating that the growth of the particle size also increased with increasing RH. Analysis of the SOA with Fourier-transform infrared (FTIR) spectrometry indicated that the particles generated from C2H2 contained the functional groups –OH, C=O, C–O–C and C–C–OH, for whose absorption peaks increase with increasing RH.

scholarly journals Hygroscopicity of Internally Mixed Ammonium Sulfate and Secondary Organic Aerosol Particles Formed at Low and High Relative Humidity

2022 ◽  
Author(s):  
Patricia N Razafindrambinina ◽  
Kotiba A Malek ◽  
Joseph Nelson Dawson ◽  
Kristin DiMonte ◽  
Timothy M Raymond ◽  
...  
Keyword(s):  
Organic Matter ◽  
Relative Humidity ◽  
Ammonium Sulfate ◽  
Secondary Organic Aerosol ◽  
Aerosol Particles ◽  
Organic Aerosol ◽  
High Relative Humidity ◽  
Volatile Organic

Volatile organic matter that is suspended in the atmosphere such as α-Pinene and β-caryophyllene undergoes aging processes, as well as chemical and photooxidation reactions to create secondary organic aerosol (SOA),...

scholarly journals Sensitivities of the absorptive partitioning model of secondary organic aerosol formation to the inclusion of water

2009 ◽  
Vol 9 (9) ◽  
pp. 2919-2932 ◽  
Author(s):  
M. Barley ◽  
D. O. Topping ◽  
M. E. Jenkin ◽  
G. McFiggans
Keyword(s):  
Relative Humidity ◽  
Condensed Phase ◽  
Individual Component ◽  
Molar Mass ◽  
Organic Aerosol ◽  
Specific Form ◽  
The Other ◽  
Aerosol Formation ◽  
Ambient Relative Humidity ◽  
Volatile Organic

Abstract. The predicted distribution of semi-volatile organic components between the gaseous and condensed phase as a function of ambient relative humidity and the specific form of the partitioning model used has been investigated. A mole fraction based model, modified so as not to use molar mass in the calculation, was found to predict identical RH dependence of component partitioning to that predicted by the conventional mass-based partitioning model which uses a molar mass averaged according to the number of moles in the condensed phase. A recently reported third version of the partitioning model using individual component molar masses was shown to give significantly different results to the other two models. Further sensitivities to an assumed pre-existing particulate loading and to parameterised organic component non-ideality are explored and shown to contribute significantly to the variation in predicted secondary organic particulate loading.

scholarly journals Aging of atmospheric aerosols and the role of iron in catalyzing brown carbon formation

2021 ◽  
Author(s):  
Hind A. A. Al-Abadleh
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Atmospheric Aerosols ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Atmospheric Oxidation ◽  
Carbon Formation ◽  
Brown Carbon ◽  
Volatile Organic

Extensive research has been done on the processes that lead to the formation of secondary organic aerosol (SOA) including atmospheric oxidation of volatile organic compounds (VOCs) from biogenic and anthropogenic...

Sign in / Sign up

Export Citation Format

Share Document