CN111624143B - Method for measuring volume equivalent diameter and effective density of aerosol particles - Google Patents

Method for measuring volume equivalent diameter and effective density of aerosol particles Download PDF

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CN111624143B
CN111624143B CN202010462229.2A CN202010462229A CN111624143B CN 111624143 B CN111624143 B CN 111624143B CN 202010462229 A CN202010462229 A CN 202010462229A CN 111624143 B CN111624143 B CN 111624143B
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aerosol
particles
particle size
equivalent diameter
density
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CN111624143A (en
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彭龙
张国华
毕新慧
李磊
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Guangzhou Institute of Geochemistry of CAS
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
    • G01N15/02—Investigating particle size or size distribution
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity

Abstract

The invention discloses a method for measuring the volume equivalent diameter and the effective density of aerosol particles. The method utilizes an aerosol dynamic particle size screening instrument-single particle aerosol mass spectrometer combined system to realize the volume equivalent diameter D of the particlesveAnd effective density ρeBecause the single-particle aerosol mass spectrometer can represent the chemical components of single particles, the invention can also realize the measurement of particles D with different chemical componentsveAnd ρeOn-line measurement of (a). The invention realizes the first time that the particles D with different components can be applied to the actual atmosphereveAnd ρeThe measurement of (2) has important significance in the aspect of particle physical and chemical property measurement technology.

Description

Method for measuring volume equivalent diameter and effective density of aerosol particles
Technical Field
The invention belongs to the technical field of environmental monitoring and analysis, and particularly relates to a method for measuring the volume equivalent diameter and the effective density of aerosol particles.
Background
Aerosol particles have important effects on climate, environment and human health, which are largely dependent on the physicochemical properties of the particles. The accurate characterization of the physical and chemical properties of the particles, especially the particle size, density and chemical composition, is of great significance for understanding the aging process and the effect of the particles.
(1) Background of particle size research and State of the Art of measurement
For spherical particles, the diameter is the particle size of the particles. The diameter of the spherical particles can be measured by techniques such as particle size spectrometers. For non-spherical particles, volume equivalent diameter (D) is typically usedve) Denotes the size of the particles, i.e. the diameter of a sphere of equal volume to the particle. DveThe physical quantity which is used for representing the actual size of the particulate matters is an important variable for researching the atmospheric behavior of the particulate matters in the field of atmospheric science. However, there is currently no technique for accurately measuring D for non-spherical particlesve。
(2) Background of research and State of the Art of measurement of Density
Density (p)p) Is one of the most important physical properties of aerosol particles, determines the sedimentation transport properties of the particles in the actual atmosphere and in the human respiratory system, and affects the optical properties of the aerosol. Further, ρpOr the electromigration size (D) of the aerosolm) Conversion to aerodynamic diameter (D)a) And important parameters when converting aerosol number concentration distribution into mass concentration. Because the prior art cannot effectively measure the density (rho) of the particulate matterp) And the shape factor (χ) of the particles (shape factor is a factor for describing the shape of the particles: usually χ ═ 1, indicating that the particulate matter is spherical; the more χ is greater than 1, the more the shape deviates from a spherical shape), so the effective density (ρ) is generally usede) The properties of the particulate matter are characterized. RhoeThere are three definitions, where two define ρeThere is an inherent property that decreases with increasing particle size, but this downward trend cannot currently be accurately assessed and corrected. And p defined in the thirde(ρe＝ρpχ) has a particle diameter not dependent on particle diameterThe changed characteristics are more reasonable to characterize the properties of the particles. However, no technique is currently available for measuring this ρ of particulate mattere。
Disclosure of Invention
The invention aims to solve the problem that the volume equivalent diameter D of the particulate matter is not measured in the prior artveAnd effective density ρeThe art of (a) provides a method for measuring the volume equivalent diameter and effective density of aerosol particles.
D of particulate matterveAnd ρeAre important physicochemical properties of the particulate matter, which all determine its transport characteristics in the atmosphere and in the human respiratory system and may influence its ability to absorb or reflect solar radiation. RhoeThe morphological information of the particles is also reflected to a certain extent, and can also be used as one of indexes of physicochemical processes which the particles undergo in the atmosphere. However, at present, D for measuring particulate matter is not achievedveAnd ρeThe technique of (1).
Thus, to achieve the particulate matter DveAnd ρeThe method designs an Aerodynemic aerosol classifier-Single particle aerosol mass spectrometer (AAC-SPAMS) combined system for the first time, and realizes the measurement of two properties of the particulate matters. Because SPAMS in the designed technical route can characterize the chemical components of single particles, the invention can also realize the separation of particles D with different chemical componentsveAnd ρeOn-line measurement of (a).
The method for measuring the volume equivalent diameter and the effective density of the aerosol particles comprises the following steps:
a. constructing a measuring system: a vent pipe is sequentially connected in series with a drying pipe, an aerosol dynamic particle size screening instrument and a single-particle aerosol mass spectrometer; setting the kinetic particle size D of an Aerosol kinetic particle size Screena(ii) a The aerosol enters an aerosol dynamic particle size screening instrument through a drying pipe, and the particle size in the aerosol is DaThe particles pass through an aerosol dynamic particle size screening instrument and then enter a single-particle aerosol mass spectrometer to measure the particlesChemical composition and vacuum kinetic particle size Dva；
b. Based on set DaAnd measured DvaUsing the following formula:
Figure BDA0002511335590000021
wherein, C (D)a) And C (D)ve) Respectively correspond to DaAnd DveThe cunningan correction factor; calculating to obtain the volume equivalent diameter D of the particlesve；
Then based on the measured DvaAnd calculated DveUsing the following formula:
Figure BDA0002511335590000022
where ρ ispIs the density of the particles, p0Has a unit density of 1.0g/cm3，χvIs a shape factor in the free molecular state; calculating to obtain rhop/χvI.e. the effective density ρ of the particlese(ρe＝ρp/χv)。
Preferably, the aerosol is treated with a PM2.5 cutting head before entering the drying tube.
Preferably, the kinetic particle size D of the aerosol kinetic particle size screening instrumentaThe setting range is 250nm-550 nm.
In conclusion, the invention realizes the particle D for the first time through the technical route of AAC-SPAMS (Aerosol dynamic particle size screener-single particle aerosol mass spectrometer)veAnd ρpMeasurement of/χ. Since SPAMS has chemical components for characterizing particles, D of particles with different chemical components can be measured in actual atmospheric observation by applying the technologyveAnd ρe。
Because no technical means can measure the D of the non-spherical particles at presentveAnd ρe. The invention realizes the difference of actual atmosphere for the first timeComponent particles DveAnd ρeThe measurement of (2) has important significance in the aspect of particle physical and chemical property measurement technology.
Drawings
FIG. 1 is a schematic representation of the use of AAC-SPAMS in combination.
FIG. 2 is a Gaussian fit DveD of spherical PSL 203.0nm, 310.0nm, 510.0nm and 740.0nmvaThe number distribution of the particulate matter.
FIG. 3 is a graph of D measuring PSLve(Dve,me)、ρe(ρe,me) Comparison with the theoretical value, (a) measurement of D of PSLve(Dve,me) And theoretical Dve(Dve,th) (ii), (b) measuring ρ of the PSLe(ρe,me) And theoretical rhoe(ρe,th) Comparison of (1).
FIG. 4 is a Gaussian fitting DaNon-spherical aerosol particles ((NH) at 250.0nm, 350.0nm, 450.0nm and 550.0 nm)4)2SO4And NaNO3) D of (A)vaThe number distribution of the particulate matter.
Detailed Description
The following examples are further illustrative of the present invention and are not intended to be limiting thereof.
FIG. 1 shows the Aerodynamic aerosol class analyzer (model AAC, Cambustion) -Single particulate aerosol mass spectrometer (AAC-SPAMS) system for realizing the analysis of different chemical components of particulate matter DveAnd ρeThe measurement of (2) is performed. The Diffusion dry tube is a drying tube having a drying effect for removing moisture contained in the aerosol.
The measurement system constructed by the method shown in fig. 1 utilizes a vent pipe to sequentially connect a drying pipe, an aerosol dynamic particle size screening instrument and a single-particle aerosol mass spectrometer in series.
When the aerosol is measured, the aerosol is dried by a drying tube, and after dried particles enter an AAC (Aerosol dynamic particle size screener), only the setting with the AAC is setDynamic particle size (D)a) Uniform particles can pass through. After passing through AAC, the particle diameter is DaInto a SPAMS (single particle aerosol mass spectrometer). SPAMS can measure the chemical composition and the vacuum dynamic particle size (D) of particulate matterva)。
DaAnd DveIs shown in formula (1):
Figure BDA0002511335590000031
wherein C (D) is a cunningham correction factor, C (D)a) And C (D)ve) Is DaAnd DveKanningan slip correction coefficient, chitIs the shape factor in the transition state, ppIs the density of the particles, p0Is unit density (═ 1.0 g/cm)3)。
DvaAnd DveIs shown in formula (2):
Figure BDA0002511335590000032
wherein, χvIs a form factor in the free molecular state.
AAC-SPAMS can obtain D of particulate matter simultaneouslyaAnd Dva. Substituting formula (1) into formula (2) to obtain formula (3):
Figure BDA0002511335590000041
wherein xtHexix-vCan be approximately equal, so equation (4) is obtained:
Figure BDA0002511335590000042
d of the particles can be obtained by using AAC-SPAMSaAnd DvaThus, by the formula (4), the particle can be obtainedObject Dve. Further, by the formula (2), D is obtained based on the calculationveAnd measured DvaThe rho of the particles can be obtainede (＝ρp/χv)。
Example 1: for known DveAnd ρeAerosol measurement verification
To illustrate the accuracy and reliability of the technical route, AAC-SPAMS was applied to known DveAnd ρeThe aerosol (spherical Polystyrene (PSL), pellets and non-spherical ammonium sulfate and sodium nitrate) of (a result obtained in this experiment was based on the number of measured particles being around 6000) was measured and compared with the theoretical value.
Spherical aerosol:
the density of the PSL was 1.055g/cm3Shape factor of 1.00, corresponding to an effective density of 1.055g/cm3. Theory D of different PSLsveRespectively as follows: 203.0nm, 310.0nm, 510.0nm and 740.0 nm.
Four kinds of DvePSL set for spherical Aerosol DaRespectively is as follows: 210.4nm, 320.4nm, 525.8nm and 762.0 nm.
Non-spherical aerosol:
the density of the ammonium sulfate is 1.77g/cm3Shape factor of 1.06, corresponding to an effective density of 1.67g/cm3(ii) a The density of the sodium nitrate is 2.26g/cm3Shape factor 1.07, corresponding to ρeIs 2.11g/cm3。
D of non-spherical Aerosol in the experimentaRespectively setting as follows: 250.0nm, 350.0nm, 450.0nm and 550.0 nm.
Although there was no other technical verification of the measurement of non-spherical particles D using this methodveBut due to peIs based on DveAnd DvaObtained so that only the measured p needs to be verifiedeThe accuracy of the effective density of the known material can be simultaneously verified, and the effective density (rho) measured by the method can be simultaneously verifiede) And DveThe accuracy of (2).
The experimental method for verification is that PSL and sulfuric acid are usedAmmonium ((NH)4)2SO4) Sodium nitrate (NaNO)3) Dissolving in pure water, generating aerosol by aerosol generator, selecting specific D by AACa. Then enters SPAMS to obtain D of the particlesva. Because AAC and SPAMS have deviation in particle size measurement, a fitting curve needs to be obtained through Gaussian fitting, and the highest value of the fitting curve is the effective D of the particlesva。
Results for spherical particles: FIG. 2 showsveMeasured D of particles of PSL at 203.0nm, 310.0nm, 510.0nm and 740.0nm in SPAMSvaThe result of (1).
According to measured DvaAnd set DaBy equation (4), the D of the AAC-SPAMS measurement is obtainedve(Dve,me) The results are shown in FIG. 3 (a). And theory Dve(Dve,th) The deviations are respectively: 0.3%, -0.1%, 0.3% and-0.4%. By Dve,meAnd DvaThe calculation of (a) obtains rho measured by AAC-SPAMSe,meAre respectively 1.06g/cm3、1.03g/cm3、1.04g/cm3And 1.09 g/cm3As shown in fig. 3 (b). The deviations are respectively: 0.8%, -2.4%, -1.1%, and 2.9%.
Results for non-spherical particles: FIG. 4 showsa(NH) at 250.0nm, 350.0nm, 450.0nm and 550.0nm4)2SO4And NaNO3Measured D of particulate matter in SPAMSva。
By setting DaAnd measured DvaCalculated result Dve,meThen through Dve,meAnd DvaCalculating to obtain rhoe,meThe results are shown in Table 1.
TABLE 1 with differences Da(NH)4)2SO4And NaNO3D of (A)vemeAnd ρe,me
Figure BDA0002511335590000051
Combining spherical and non-spherical particlesThe measurement result of the object can be known, and the D of the spherical particles is measured by the methodve,meWithin 1% error, pe,meThe deviation of (A) is within 3%; rho of non-spherical particlese,meThe deviation of (a) is within 5%.
These results demonstrate that D, the particle size of which can be accurately characterized by the present methodveAnd ρe. Furthermore, it must be noted that: the main source of these 5% errors is caused by errors in the particle size calibration curve of the SPAMS. Thus, averaging the results of the four different particle sizes, the (NH) measured by the method can be obtained4)2SO4And NaNO3Rho ofeRespectively as follows: 1.68g/cm3And 2.11g/cm3. Almost with the p of the particles themselveseAnd (4) completely inosculating.
Example 2: measuring particulate matter in atmosphere
The method comprises the following steps of (1) determining particles in the atmosphere by using an AAC-SPAMS combined method:
the black rubber pipe is connected into the actual atmosphere (in order to reduce the damage of large particles to the instrument and equipment, the black rubber pipe is connected to the lower end of a PM2.5 cutting head), then the pipeline passes through the drying pipe and then is connected with the AAC, and finally the pipeline is in butt joint with the air inlet of the SPAMS. Because AAC and SPAMS in the method are mature commercial instruments, the specific connection is directly according to the use instructions provided by manufacturers. When measuring external field, only D for AAC is neededaThe setting is carried out, and the recommended setting range is 250nm-550 nm.
The following is the method for measuring different chemical component particles D in the atmosphere of Guangzhou cityveAnd ρe(the data obtained in this experiment are based on measurements of the number of particles of about 100000), DaSet to 250nm, 350nm, 450 nm and 550 nm.
The particulate matter was classified into the following eight classes according to the chemical composition of the particulate matter measured by SPAMS (Table 2). Then according to the formula (4), obtaining D of different types of particlesveSubstituting the formula (2) to obtain rho of the particleseThe results are shown in Table 3.
TABLE 2 different types of particulate matter at Da250.0nm and 350.D at 0nm, 450.0nm and 550.0nmve
Figure BDA0002511335590000061
TABLE 3 different types of particulate matter at DaRho values at 250.0nm, 350.0nm, 450.0nm and 550.0nme
Figure BDA0002511335590000062
Figure BDA0002511335590000071

Claims (2)

1. A method of measuring the volume equivalent diameter and effective density of aerosol particles comprising the steps of:
a. constructing a measuring system: a vent pipe is sequentially connected in series with a drying pipe, an aerosol dynamic particle size screening instrument and a single-particle aerosol mass spectrometer; setting the kinetic particle size D of an Aerosol kinetic particle size ScreenaSetting the range to be 250nm-550 nm; the aerosol enters an aerosol dynamic particle size screening instrument through a drying pipe, and the particle size in the aerosol is DaThe particles pass through an aerosol kinetic particle size screening instrument and then enter a single-particle aerosol mass spectrometer to measure chemical components and vacuum kinetic particle size D of the particlesva；
b. Based on set DaAnd measured DvaUsing the following formula:
Figure FDA0003112137370000011
wherein, C (D)a) And C (D)ve) Respectively correspond to DaAnd DveThe cunningan correction factor; calculating to obtain the volume equivalent diameter D of the particlesve；
Then based on the measured DvaAnd calculated DveUsing the following formula:
Figure FDA0003112137370000012
where ρ ispIs the density of the particles, p0Has a unit density of 1.0g/cm3，χvIs a shape factor in the free molecular state; calculating to obtain rhop/χvI.e. the effective density ρ of the particlese。
2. The method of claim 1, wherein the aerosol is treated with a PM2.5 cutting head prior to entering the drying tube.
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0755689A (en) * 1993-08-16 1995-03-03 Agency Of Ind Science & Technol Aerosol particle mass spectrograph
CN102262039A (en) * 2011-04-27 2011-11-30 上海大学 Method and device for detecting indoor heavy metal pollution by using single particle aerosol mass spectrometer (SPAMS)
CN102608004A (en) * 2012-03-14 2012-07-25 北京汇丰隆生物科技发展有限公司 Aerodynamic size spectrometer
CN105067490A (en) * 2015-08-12 2015-11-18 广东省环境监测中心 Monitoring method of online SPAMS (single particle aerosol mass spectrometer)
CN105954070A (en) * 2016-04-29 2016-09-21 南京信息工程大学 Aerosol particle collection device
CN106932302A (en) * 2017-03-09 2017-07-07 中国工程物理研究院核物理与化学研究所 A kind of density measuring method of plutonium aerosol list particulate

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0755689A (en) * 1993-08-16 1995-03-03 Agency Of Ind Science & Technol Aerosol particle mass spectrograph
CN102262039A (en) * 2011-04-27 2011-11-30 上海大学 Method and device for detecting indoor heavy metal pollution by using single particle aerosol mass spectrometer (SPAMS)
CN102608004A (en) * 2012-03-14 2012-07-25 北京汇丰隆生物科技发展有限公司 Aerodynamic size spectrometer
CN105067490A (en) * 2015-08-12 2015-11-18 广东省环境监测中心 Monitoring method of online SPAMS (single particle aerosol mass spectrometer)
CN105954070A (en) * 2016-04-29 2016-09-21 南京信息工程大学 Aerosol particle collection device
CN106932302A (en) * 2017-03-09 2017-07-07 中国工程物理研究院核物理与化学研究所 A kind of density measuring method of plutonium aerosol list particulate

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
Determination of particle mass, effective density, mass–mobility exponent, and dynamic shape factor using an aerodynamic aerosol classifier and a differential mobility analyzer in tandem;Farzan Tavakoli 等;《Journal of Aerosol Science》;20140426;第75卷;第35-42页 *
Mass spectrometric analysis and aerodynamic properties of various types of combustion-related aerosol particles;J. Schneider 等;《International Journal of Mass Spectrometry》;20060830;第258卷;第37-49页 *
Particle Morphology and Density Characterization by Combined Mobility and Aerodynamic Diameter Measurements. Part 1: Theory;Peter F. DeCarlo 等;《Aerosol Science and Technology》;20120801;第1185-1205页 *
单颗粒气溶胶质谱测定颗粒的有效浓度;张国华 等;《中国科学》;20151120;第45卷(第12期);第1887-1888页 *

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