Grantee Research Project Results

2000 Progress Report: Development of an Electrodynamic Quadrupole Aerosol Concentrator

EPA Grant Number: R827354C006
Subproject: this is subproject number 006 , established and managed by the Center Director under grant R827354
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Airborne PM - Rochester PM Center
Center Director: Oberdörster, Günter
Title: Development of an Electrodynamic Quadrupole Aerosol Concentrator
Investigators: Ensor, David
Institution: Research Triangle Institute
EPA Project Officer: Chung, Serena
Project Period: June 1, 1999 through May 31, 2004 (Extended to May 31, 2006)
Project Period Covered by this Report: June 1, 2000 through May 31, 2001
RFA: Airborne Particulate Matter (PM) Centers (1999) RFA Text |  Recipients Lists
Research Category: Particulate Matter , Air Quality and Air Toxics , Air

Objective:

The objective of this pilot project is to develop a new approach for concentrating ultrafine particles for animal inhalation studies. The electrodynamic aerosol concentrator invented by Periasamy, Ensor, and Donovan (1995) uses an ac field quadrupole to deflect the particles to the center of a flowing gas stream between the electrodes. Experiments conducted earlier with monodisperse 14 ?m oleic acid aerosols tagged with uranine dye an electrodynamic quadrupole demonstrated significant focusing. Two key questions are addressed in this research: (1) Can the performance be extended to sub 0.1 µm particles? (2) Can the device be scaled up to provide sufficient flow for laboratory studies?

Progress Summary:

During the second year, the Research Triangle Institute has focused on theoretical analysis and laboratory experiments. The theoretical analysis performed by Dr. Seok Joo Park during a postdoctoral appointment at University of Minnesota (Park, et al., Electrodynamic Focusing of Charged Fine Particle Using Alternating 2-Dimensional Quadrupole Electric Field, 2000) was extended by Dr. John Franke of North Carolina State University, Department of Mathematics. Additional theoretical analysis confirms our finding that focusing and concentrating on particles smaller than 0.1 µm at atmospheric pressure will be difficult. The key parameter is the level of charge on the particles.

A series of experiments was conducted with monodisperse oleic acid uranine dye aerosols (1 to 15 µm) generated with a vibrating orifice aerosol generator using a ring electrode charger. The focusing was determined by using the dye image formed on a filter placed after the quadrupole section. These experiments demonstrated significant focusing of particles at 1 mm. The quadrupole used in these experiments was 20 cm long with 1.3 cm diameter electrodes in a 3.8 cm diameter tube. This experimental approach was limited to 1 Fm aerosol by the ability to detect the dye patterns on the surface of the filter.

Because the eventual application of the device will be to concentrate atmospheric aerosol, we are looking at aerosol charging and equipment scale up. The experiments conducted over the last 6 months have taken a different approach of building a larger quadrupole with 1.9 cm diameter electrodes in a 10 cm diameter tube with length up to 210 cm. A PMS LAS-X particle counter was used to traverse the exhaust of the quadrupole. The results to date have been inconclusive because of experimental limitations from aerosol charging. The major difficulty has been to obtain adequate charge without precipitating the particles in the charger.

A novel aerosol charger based on the design reported by Cheng, et al. (Aerosol Science and Technology 1997;26:433-446) has been constructed and tested. This charger has a porous outer wall with central corona discharge. Transpiration flow through the porous wall is used to prevent deposition of charged particles on the wall.

Future Activities:

In the final months of the second year, our priority will be to document the research conducted under this project for a peer-reviewed paper. Two-dimensional quadrupoles may be an important aerosol research tool in appropriate applications requiring transporting and focusing of aerosols. The paper will include numerical analysis of the particle equations of motion by two different solvers and experiments under atmospheric pressure. The numerical solutions for the two-dimensional geometry previously have only been approximated by Masuda, et al. (Journal of the Institute of Electrical Engineers of Japan 1970;90:861-869), and there are important differences from the solutions for the three-dimensional case reported by Davis (Langmuir 1985;1:379-387). The experimental results will be limited to the successful test setups and will stress the mating of the aerosol charger and the concentrator. A preliminary title for the paper is: Electrodynamic Focusing of Charged Fine Particles Using Alternating 2-Dimensional Quadrupole Electric Fields.

Supplemental Keywords:

pollution prevention, atmosphere, particulates, metals, sensitive population., RFA, Health, Air, Scientific Discipline, Virology, Health Risk Assessment, Risk Assessments, particulate matter, Environmental Chemistry, Epidemiology, Atmospheric Sciences, Biochemistry, aerosols, sensitive populations, epidemelogy, electrodynamic quadrupole aerosol concentrator, chemical characteristics, particle size, pulmonary disease, urban environment, fine particles, human exposure, mortality, ambient air monitoring, cardiopulmonary responses, particulate exposure, environmental health effects, particulates, susceptible populations, chemical speciation sampling, chemical kinetics, ambient air quality, human health effects, ultrafine particles

Relevant Websites:

http://www2.envmed.rochester.edu/envmed/pmc/indexpmc.html Exit

Progress and Final Reports:

Original Abstract

1999 Progress Report

2001

2002

2003

2004

Final

Main Center Abstract and Reports:

R827354    Airborne PM - Rochester PM Center

Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R827354C001 Characterization of the Chemical Composition of Atmospheric Ultrafine Particles
R827354C002 Inflammatory Responses and Cardiovascular Risk Factors in Susceptible Populations
R827354C003 Clinical Studies of Ultrafine Particle Exposure in Susceptible Human Subjects
R827354C004 Animal Models: Dosimetry, and Pulmonary and Cardiovascular Events
R827354C005 Ultrafine Particle Cell Interactions: Molecular Mechanisms Leading to Altered Gene Expression
R827354C006 Development of an Electrodynamic Quadrupole Aerosol Concentrator
R827354C007 Kinetics of Clearance and Relocation of Insoluble Ultrafine Iridium Particles From the Rat Lung Epithelium to Extrapulmonary Organs and Tissues (Pilot Project)
R827354C008 Ultrafine Oil Aerosol Generation for Inhalation Studies