DOI

10.17077/etd.xq0cyjgx

Document Type

Thesis

Date of Degree

Spring 2017

Degree Name

MS (Master of Science)

Degree In

Occupational and Environmental Health

First Advisor

Peters, Thomas M.

First Committee Member

Anthony, Teresa R.

Second Committee Member

O'Shaughnessy, Patrick T.

Abstract

A high-flow (10 L/min) nanoparticle respiratory deposition (NRD) sampler was designed and evaluated to facilitate lower limits of quantification (LOQ) for metal nanoparticles than a low-flow (2.5 L/min) version. The high-flow NRD consists of an inlet, impactor stage, diffusion stage, and a final filter. For the impactor stage, three nozzle sections each containing 12 nozzles were designed from theory to achieve a cut-off diameter (d50) of 300 nm. Various depths of 37-mm-diameter foam cylinders were tested for the diffusion stage to obtain a collection efficiency curve similar to the deposition of nanoparticles in the human respiratory tract, the nanoparticulate matter (NPM) criterion. The objective for the final filter was a collection efficiency of near 100% with minimal pressure drop. The collection efficiencies by size and pressure drop were measured for all components. The impactor stage with one of the nozzle plates had a d50 of 305 nm. The collection efficiency for the foam with a depth of 7 cm adjusted for presence of the impactor was the closest match to the NPM curve with a R2 value of 0.96. Chemical analysis of the metal content for foam media affirmed that the high-flow NRD would require less sampling time to meet LOQs than the 2.5 L/min NRD. The final filter with a modified support pad had a collection efficiency near 100%. The overall pressure drop of the sampler 4.4 kPa (17.5 in. H2O) limits its ability to operate with available belt-mounted personal sampling pumps, although modifications to the sampler design could eliminate this constraint.

Public Abstract

A high-flow nanoparticle respiratory deposition (NRD) sampler was designed and evaluated. The high-flow NRD sampler was created to reduce the required sampling time by collecting more mass in a shorter period of time. The high-flow NRD consists of an inlet, impactor stage, diffusion stage, and a final filter. For the impactor stage, three nozzle sections containing 12-nozzles were designed from theory. Various depths of foam cylinders were tested for the diffusion stage to obtain a collection efficiency curve similar to deposition of nanoparticles in the human respiratory tract. The objective for the final filter was a collection efficiency of near 100% with minimal pressure drop. The collection efficiencies by size and pressure drop were measured for all components. The collection efficiency for the foam depth of 7 cm adjusted for the presence of one the designed and tested impactor sections was the closest match to the target curve. Background metal content via chemical analysis of the foam media confirmed that the high-flow NRD would require minimal sampling time to collect the necessary mass for analysis. The final filter obtained a collection efficiency near 100% but the reduction in pressure drop was minimal. The pressure drop of the sampler limits its ability to operate with available belt-mounted personal pumps, although modifications to the sampler could eliminate this obstruction.

Keywords

Aerosols, Nanotechnology, Sampling & Analysis

Pages

ix, 61 pages

Bibliography

Includes bibliographical references (pages 59-61).

Copyright

Copyright © 2017 Theresa Iren Szabo McCollom

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