Bipolar diffusion charging of spheres and agglomerate aerosol particles

Abstract The effect of particle shape on the diffusion charging of aerosols was investigated. The charging-equivalent sphere diameter d QE , found previously to be much larger than the mobility diameter d m , may be related to the uncharged fraction of particles leaving a bipolar diffusion charger. This fraction was measured for three types of particles classified by electrical mobility: polystyrene latex (PSL) spheres, ammonium sulfate spheres and TiO 2 agglomerates of 10–20 nm primary particles. The uncharged fraction was ∼5% lower for the agglomerates than for spheres with the same mobility, for size range 100 d m d QE ∼ 1.1 d m for the agglomerates, which is a smaller difference between d QE and d m than reported by previous studies, but is consistent with the theoretical predictions (Laframboise and Chang, 1977, J. Aerosol Sci. 8 , 331–338).

[1]  K. T. Whitby,et al.  Aerosol classification by electric mobility: apparatus, theory, and applications , 1975 .

[2]  G. M. Frick,et al.  The Nonequilibrium Character of the Aerosol Charge Distributions Produced by Neutralizes , 1990 .

[3]  G. Kasper,et al.  Dynamics and Measurement of Smokes III—Drag and Orientation of Chain Aggregates in an Electrical Mobility Spectrometer , 1984 .

[4]  K. T. Whitby,et al.  Bipolar Steady State Charge Fraction of Ultrafine Aerosols , 1984 .

[5]  James W. Gentry,et al.  Structural analysis of soot agglomerates , 1987 .

[6]  G. Kasper,et al.  Bipolar diffusion charging of fibrous aerosol particles. I: Charging theory , 1984 .

[7]  D. Pui,et al.  Bipolar Diffusion Charging of Aerosol Particles Under High Particle/Ion Concentration Ratios , 1989 .

[8]  K. T. Whitby,et al.  The charging and mobility of chain aggregate smoke particles , 1967 .

[9]  Kikuo Okuyama,et al.  Unipolar and bipolar diffusion charging of ultrafine aerosol particles , 1984 .

[10]  G. M. Frick,et al.  Ion—Aerosol Attachment Coefficients and the Steady-State Charge Distribution on Aerosols in a Bipolar Ion Environment , 1986 .

[11]  P. Mcmurry,et al.  A Device for Generating Singly Charged Particles in the 0.1-1.0-μm Diameter Range , 1989 .

[12]  G. Kasper,et al.  Bipolar diffusion charging of fibrous aerosol particles. II: Charge and electrical mobility measurements on linear chain aggregates , 1984 .

[13]  J. H. Vincent,et al.  On the practical significance of electrostatic lung deposition of isometric and fibrous aerosols , 1985 .

[14]  Image potential between a charged particle and an uncharged particle in aerosol coagulation—enhancement in all size regimes and interplay with van der Waals forces , 1991 .

[15]  J. Gentry,et al.  Differences in diffusion charging of dielectric and conducting ultrafine aerosols , 1985 .

[16]  Steven N. Rogak,et al.  Measurement of Mass Transfer to Agglomerate Aerosols , 1991 .

[17]  Barton E. Dahneke,et al.  Slip correction factors for nonspherical bodies—III the form of the general law , 1973 .

[18]  K. Becker,et al.  Bipolar diffusion charging of aerosol particles—I: experimental results within the diameter range 4–30 nm , 1983 .

[19]  D. Shaw,et al.  Comparative size distribution measurements on chain aggregates , 1982 .

[20]  B. M. Smirnov The properties of fractal clusters , 1990 .

[21]  Calculations and measurements of the charge distribution for non-spherical particles , 1988 .

[22]  U. Baltensperger,et al.  Scaling behaviour of physical parameters describing agglomerates , 1990 .

[23]  J. Gentry Charging of aerosol by unipolar diffusion of ions , 1972 .

[24]  K. W. Lee,et al.  An aerosol generator of high stability. , 1975, American Industrial Hygiene Association journal.

[25]  Paul Meakin,et al.  Collisions between point masses and fractal aggregates , 1989 .

[26]  B. Dahneke Slip correction factors for nonspherical bodies—II free molecule flow , 1973 .

[27]  T. Witten,et al.  Long-range correlations in smoke-particle aggregates , 1979 .

[28]  A. Schmidt-Ott,et al.  Particle charge in combustion aerosols , 1986 .

[29]  K. Okuyama,et al.  Determination of particle size distribution of ultra-fine aerosols using a differential mobility analyzer , 1985 .

[30]  N. Fuchs,et al.  On the stationary charge distribution on aerosol particles in a bipolar ionic atmosphere , 1963 .

[31]  K. Okuyama,et al.  Calibration of differential mobility analyser by visual method , 1981 .

[32]  C. C. Wang,et al.  Experimental measurement of the rate of unipolar charging of actinolite fibers , 1987 .

[33]  G. Kasper,et al.  Measurements of viscous drag on cylinders and chains of spheres with aspect ratios between 2 and 50 , 1985 .

[34]  David Y. H. Pui,et al.  Electrical neutralization of aerosols , 1974 .

[35]  W. B. Johnston,et al.  Static electrification of airborne asbestos: a study of its causes, assessment and effects on deposition in the lungs of rats. , 1981, American Industrial Hygiene Association journal.

[36]  Jen-Shih Chang,et al.  Theory of charge deposition on charged aerosol particles of arbitrary shape , 1977 .