Imaging and Analysis of Ultrafine Environmental Particles

University of Rochester - April 2004

Opt507 - by David Chalupa

Introduction:

Environmental air samples were collected from four different sources: Indoor, Outdoor, Concentrated Ambient Particles (CAPs), and lab generated carbon. The goals of this project were: To verify particle sizes, Get some compositional information, and to Identify differences in the morphology of each group. Several different imaging/sizing methods were used to best describe the particles (SEM, TEM, Electrical Mobility Separation (in-flight sizing)). X-ray spectrometry (EDAX) was used to get some compositional information.

Sources:

Outdoor Site (Kendrick Road)
 
Ultrafine Particle Concentrator
 
Indoor Sampling Method
   

Particle Concentrator:

The particle concentrator was developed as a joint effort from Harvard University and the Environmental Protection Agency (EPA). It collects ambient air at a high inital flowrate of 2000 L/min. The particles are then conditioned with condensate, separated with two high-volume virtual imapactors, and dried until only the ultrafine particles (<1 micron) are retained at a concentrated number. A concentrating factor of 30 times is possible.

Conventional Impactor
 
Virtual Imactor
 

 

In-flight Sizing:

   
CAPs
 
Outdoor
 
Indoor

Collection Data:

Sample

Collection Time (Hrs.)

Weight (ug)
Count Median Diameter (nm)

# Conc. (p/cm3)

(x10^4)

CAPs
1
296
59.8
24.6
Outdoor
2
59
43.4
1.04
Indoor
17.5
36
77.1
0.128

Back to the top

 

Low Mag. SEM (Secondary Electron) Images (5,000x):

Indoor
 
CAPs
 
Outdoor
   

 

Medium Mag. SEM (Secondary Electron) Images (10,000x):

Indoor
 
CAPs
 
Outdoor
   

 

High Mag. SEM (Secondary Electron) Images (100,000x):

Indoor
 
CAPs
 
Outdoor
   

Back to the top

 

High Mag. TEM (Transmission Electron) Images of CAPs:

 
 
x25K Mag.
 
x150K Mag.
 
x60K Mag.
 
 
x50K Mag.
 
x150K Mag.
 
x200K Mag.

Back to the top

 

SEM (Secondary Electron) Images of lab generated carbon:

 
 
x3000 Mag.
 
x10,000 Mag.
 
x20,000 Mag.
 
 
x10,000 Mag.
 
x20,000 Mag.
 
x50,000 Mag.

Back to the top

 

X-ray Spectometry (EDAX):

 
 
 
 
Indoor (Sulfates in green?)
 
CAPs (Diesel particle?)
 
Outdoor (TV Integreated Image)
 
 
Indoor
 
CAPs
 
Outdoor
Element

Samples

Sources?
C (Carbon)
All
Filter, Diesel
O (Oxygen)
All
Filter, Abundant (1st)
Au (Gold)
All
Coating
S (Sulfur, Sulfates)
Indoor
Clothing, Body Fluids, Skeletal
Na (Sodium)
Indoor
Salt, Soap
Ca (Calcium)
Outdoor
Crustal Element, Abundant (5th)
Al (Aluminum)
Outdoor
Mechanical, Construction
Mg (Magnesium)
Outdoor
Crustal Element, Abundant (8th)
Si (Silicon, Silica)
Outdoor
Crustal Element, Abundant (2nd)
K (Potassium)
Outdoor
Trace Element, Abundant (7th)
Mn (Manganese)
Conc.
Trace Element

* (Number indicates abundance of element found in the environment)

Results/Discussion:

Back to the top

 

Please enter any comments, criticisms, questions, etc. below.

Your name:

Email address: