Post on 12-Feb-2021
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FORMATION OF ACTIVE CHLORINE OXIDANTS IN SALINE-OXONE AEROSOL
By
JAEYOUN JANG
A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ENGINEERING
UNIVERSITY OF FLORIDA
2010
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© 2010 Jaeyoun Jang
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To my grandmother, Jaegeun Jung, for her endless love
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ACKNOWLEDGMENTS
Above all, I am thankful to God for always leading me in the right direction. I would
like to thank my advisor, Dr. Myoseon Jang, for her support and lessons through doing
my master study. I also wish to thank my committee, Dr. Treavor Boyer and Michael
Henley, for their time and helpful comments on this thesis. I want to thank all of my
colleagues in Dr.Jang’s group, Gang Cao, Tianyi Chen, Jiaying Li, Yunseok Lim, Min
Zhong, and Wilton Mui for the mutual learning and valuable time we spent together. I
also would like to thank Air Force and NSF for financially supporting my master study.
Finally, I wish to thank my parents, my brother and friends in Korea for their love and
prayer that can support me throughout my studies.
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TABLE OF CONTENTS
page
ACKNOWLEDGMENTS .................................................................................................. 4
TABLE OF CONTENTS .................................................................................................. 5
LIST OF TABLES ............................................................................................................ 7
LIST OF ABBREVIATIONS ............................................................................................. 9
ABSTRACT ................................................................................................................... 10
CHAPTER
1 INTRODUCTION .................................................................................................... 12
1.1 Oxone ............................................................................................................... 12 1.2 Saline-Oxone Chemistry ................................................................................... 13 1.3 Aerosolized Saline-Oxone ................................................................................ 14
2 EXPERIMENTS ...................................................................................................... 15
2.1 Monitoring of Active Chlorine in Saline-Oxone Aerosol ..................................... 15 2.2 Monitoring of Acidity of Externally Mixed Saline-Oxone Aerosol ....................... 16 2.3 Measurement of Water Amount in Saline-Oxone Particles Using FTIR ............ 17
3 RESULTS AND DISCUSSION ............................................................................... 22
3.1 Active Chlorine Formation and Its Oxidizing Effect ........................................... 22 3.2 Buffer Stability in Saline-Oxone Aerosol ........................................................... 25 3.3 Humidity Effect .................................................................................................. 26 3.4 Dynamics of Aerosol Acidity ............................................................................. 28
4 SUMMARY ............................................................................................................. 35
APPENDIX
A CALIBRATION CURVE FOR WATER CONTENT IN PARTICLES ........................ 36
B CALIBRATION CURVE FOR AEROSOL ACIDITY ................................................ 37
B.1 Experimental Procedures ........................................................................... 37 B.2 Calibration Curve ....................................................................................... 37
LIST OF REFERENCES ............................................................................................... 40
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BIOGRAPHICAL SKETCH ............................................................................................ 43
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LIST OF TABLES
Table page 2-1 Experimental conditions to study aerosol reactivity and acidity using UV-Vis
spectroscopy for the aerosol sample collected on the dyed filter with MY or TBa ..................................................................................................................... 18
2-2 Experimental conditions to monitor the water content in saline, Oxone, and saline-Oxone particles using FTIR and the estimated water amount in various particles in the two different RH at 20% and 70%. .............................................. 19
B-1 Experimental conditions and results to obtain calibration curve for aerosol acidity ................................................................................................................. 39
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LIST OF FIGURES
Figure page 2-1 UV-Visible spectroscopy to monitor the evolution of active chlorine and
aerosol acidity in both internally and externally mixed aerosols.. ....................... 20
2-2 FTIR experimental setup to measure the water amount in oxidant particles. ..... 21
3-1 The ∆A’420,oxi obtained using different sampling systems (F1-F2-F3 and F1-D-F2) for the internally mixed saline-Oxone aerosol after the Oxone was mixed with saline in the aqueous solution. .................................................................... 30
3-2 Time profile of ∆A’420,oxi of the external mixture of Oxone, saline-Oxone, saline-Oxone with phosphate buffer aerosol. ..................................................... 31
3-3 FTIR spectra of the tested buffers (sodium bicarbonate and phosphate buffer) and the subtracted FTIR spectra ([spectrum of Saline/Oxone/Buffer] – [spectrum of Saline/Oxone]). .............................................................................. 32
3-4 FTIR spectra of NaCl particles impacted on silicon FTIR window at different humidity levels. ................................................................................................... 33
3-5 The M’water of NaCl, saline, Oxone, and saline-Oxone aerosols as a function of decreasing humidity. ....................................................................................... 34
B-2 Calibration curve for calculating aerosol acidity .................................................. 39
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LIST OF ABBREVIATIONS
DRH Deliquescent relative humidity
ERH Efflorescent relative humidity
FTIR Fourier transform infrared
MY Metanil yellow
RH Relative humidity
SMPS Scanning mobility particle sizer
TB Thymol blue
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Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Engineering
FORMATION OF ACTIVE CHLORINE OXIDANTS IN SALINE-OXONE AEROSOL
By
Jaeyoun Jang
May 2010
Chair: Myoseon Jang Major: Environmental Engineering Sciences
In this study, the feasibility of producing active chlorine species from saline-
Oxone® aerosols was studied using a 2m3 Teflon film chamber. Aerosol chemistry of
saline-Oxone particles impacted on a silicon window was studied in terms of buffer
stability using a FTIR spectrometer. Between phosphate and bicarbonate buffers used
in this study, phosphate buffer was favorable for oxidant particles due to chemical
stability.
To evaluate the oxidative capability of saline-Oxone aerosol, the aerosol was
collected onto filters impregnated with a dye (e.g., MY) that react with active chlorine in
the aerosol, and monitored by UV-Visible spectroscopy. Spectral data showed that the
dye compound was 90% oxidized by active chlorine within 3 minutes. The presence of
phosphate buffer retarded the formation rate of active chlorine in saline-Oxone aerosol
particles. Only 28% of oxidation in phosphate-buffered aerosol was observed within 10
minutes after the reaction began.
The water content of aerosol particles was estimated using the FTIR absorbance
at 3350 cm-1 and the calibration curve obtained from the NaCl particles that are known
for the inorganic thermodynamic property. Unlike the NaCl particle that has the clear
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phase transition, oxidant particles (e.g., Oxone and saline-Oxone) contain significant
water mass even at a low RH (20%) with no phase transition suggesting that oxidation
in liquid-like particles progresses in the ambient humidity.
Saline-Oxone aerosols were found to be highly acidic as determined by UV-Visible
spectroscopy, indicating that the aerosol produced mostly an undissociated form of
active chlorine species (e.g., HOCl) that was susceptible to partitioning into the gas
phase.
Our study concludes that the aerosolized saline-Oxone is a feasible chlorine
oxidant, but the efficiency of such an approach still needs investigation.
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CHAPTER 1 INTRODUCTION
1.1 Oxone
Oxone® [2KHSO5KHSO4K2SO4, molecular weight (MW) =614.76 g/mol] is a triple
salt compound containing the active oxidant reagent, potassium monopersulfate
(KHSO5-). Oxone is a commonly used for a variety of industrial and consumer
applications such as swimming pool shock oxidizer (Wojtowicz et al. 1983; Gay 1994),
bleach component in denture cleanser (Eoga 1985) and laundry formulations (Eckhardt
et al. 1989).
Oxone has been utilized for efficient oxidation of organic compounds such as the
conversion of alkenes to diols, sulfides to sulfoxides, and ketones to esters (Kennedy
and Stock 1960; Webb and Ruszkay 1998; Jiang 1989). Travis et al. (2003)
demonstrated the oxidation of aldehydes to carboxylic acids or ester products using
Oxone aqueous solution. In addition, Oxone has been used to remove NOx and SO2
through aqueous absorption and oxidation in the wet scrubbing processes (Adewuyi
and Owusu 2003; Martin 2005).
Synergetic reagents have been frequently used to enhance the oxidative capability
of Oxone. For example, Schulze et al. (2006) presented an efficient method for oxidizing
alcohols using a mixture of sodium chloride (NaCl) and Oxone. Delcomyn et al. (2006)
and Wallace et al. (2005) showed that Oxone solutions buffered with sodium
bicarbonate containing a chloride salt or acetone rapidly inactivated viruses, bacteria,
and fungi and proposed that the resulting oxidant solutions appeared to be effective
bleach substitutes. Another interesting application of Oxone was reported (Raber and
McGuire 2002). L-gel was developed by adding of an aqueous solution of Oxone to a
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fumed silica gelling agent. Oxone in L-gel is effective to inactive bacteria (Raber and
McGuire 2002) and L-gel can be applied to surfaces with spray painting equipment.
However, the residual salts and silica increase the mass of waste which can be
hazardous. Also the further studies are needed to test the efficacy of L-gel. In this study,
we focused on the application of Oxone with sea salt (saline).
1.2 Saline-Oxone Chemistry
In the presence of saline aqueous solution, Oxone produces active chlorine
species such as hypochlorous acid (HOCl) and hypochlorite ion (OCl-) through the
reaction between peroxymonosulfate ion (HSO5-) in Oxone and chloride ion as follows
(Delcomyn et al. 2006)
2
5 2 5 3HSO H O SO H O (p 9.4)aK (1-1)
2
5 4HSO Cl H OCl SO (1-2)
HOCl H OCl (p 7.5)aK (1-3)
HOCl(l) HOCl(g) (1-4)
2 2HOCl+H Cl Cl +H O
(1-5)
Free chlorine is defined as the concentration of residual chlorine in water present
as dissolved gas (Cl2), HOCl and OCl-. When pH is between 2 and 7, the equilibrium is
in favor of HOCl. As the pH falls below 2, the predominant form of the chlorine is Cl2
(Wang et al. 2007). The induced active chlorine species (HOCl and OCl-) are more
powerful oxidants than Oxone alone (Delcomyn et al. 2006). The resulting HOCl in the
liquid (l) or particle (p) can evaporate to the gas phase (g) as shown in equation 1-4
thereby reducing the available active chlorine species in the aqueous solution. HOCl
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and OCl- are evenly distributed at pH 7.5 (25 C) (Feng et al. 2007) as shown in
equation 1-3, so a buffer such as sodium bicarbonate has often been used to
manipulate the distribution of HOCl and OCl- (eq.1-3) and HSO5- and SO5
2- (eq.1-1).
1.3 Aerosolized Saline-Oxone
The application of oxidative reactions of Oxone has been mainly utilized through
the aqueous solution. However, little is known about the water uptake properties and
reactivity of Oxone aerosol particles suspended in ambient air. In general, the use of
appropriate aerosolized oxidants would have significant value in remediating chemically
or biologically contaminated surfaces. For example, oxidative aerosols can penetrate
into contaminated interior spaces of structures and buildings where dissemination of
liquid decontaminants would otherwise be difficult.
The understanding of the chemistry of aerosol-phase reaction and reactivity of the
aerosolized Oxone coexisting with chloride is studied herein to determine its potential
value as a decontaminant. The results of this study help to provide an understanding of
the generation and oxidative reactivity of active chlorine from saline-Oxone aerosols.
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CHAPTER 2 EXPERIMENTS
2.1 Monitoring of Active Chlorine in Saline-Oxone Aerosol
The evolution of active chlorine in saline-Oxone aerosol was monitored by UV-
Visible spectroscopy. Figure 2-1 shows the experimental setup to monitor the reactivity
of internally or externally mixed saline-Oxone aerosol using a 2m3 Teflon film indoor
chamber. Internally mixed saline-Oxone aerosols were produced by atomizing a single
solution of saline and Oxone, while externally mixed aerosols were produced by
separately atomizing and separately impacting Oxone and saline solutions. The
chamber was flushed with air purified in house using two clean air generators (Aadco
Model 737, Rockiville, MD; Whatman Model 75-52, Haverhill, MA) prior to experiments.
The humidity of the indoor chamber air was controlled by passing the clean dry air
through a water bubbler. To study the oxidizing capability of saline-Oxone aerosol, MY
(Sigma Aldrich) dye which reacts with active chlorine produced from saline-Oxone
aerosol was used. A 16 mm sampling filter (Gelman Sciences Pallflex, Type TX40HI20-
WW) was dyed prior to particle collection in a MY aqueous solution (1.98 mg/10 mL
water) for 10 minutes and dried in room air.
For the study of the reaction in the internally mixed aerosol, the mixture (saline:
Oxone weight ratio = 1:1) made of 1% saline (sea salt, Sigma-Aldrich) and 2% Oxone
(Potassium monopersulfate triple salt, ≥47% KHSO5 basis, Sigma-Aldrich) aqueous
solutions was atomized into the indoor Teflon chamber using a medical nebulizer (LC
STAR, Pari Respiratory Equipment, Inc., Midlothian, VA). The internally mixed saline-
Oxone aerosol was sampled on two or three MY dyed filters in series with or without a
three channel annular denuder (URG-2000): the filter-filter (F1-F2), or filter-filter-filter
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(F1-F2-F3), or filter-denuder-filter (F1-D-F2) system. The denuder was coated with
K2CO3 to eliminate acidic gases such as HOCl. The sampling time was 2-3 minutes and
the flow rate was 10-11 L/min.
For the study of reaction in the externally mixed aerosol, saline particles or saline
particles buffered with phosphate (Sigma-Aldrich, 0.1 mol/L) were directly impacted on
MY-dyed filters using the nebulizer and weighed using an analytical balance (MX5
Mettler-Toledo Ltd., England) to measure the collected particle mass. Then Oxone
solution (2% W/V) was atomized by a nebulizer into the Teflon chamber and the Oxone
aerosol suspended in the chamber was collected on the dyed filter that contained the
saline or the saline-buffer particles as described above using a pump (Gast, DOA-P704-
AA) at 13 L/min for 5 minutes.
Aerosol particle size distribution and concentration were monitored with a SMPS
(TSI, Model 3080) coupled to a condensation nuclei counter (TSI, Model 3025A and
Model 3022). The aerosol sampling flow rate was 0.3 L/min, and the sheath airflow rate
was 2 L/min. Oxidation of MY-dyed filters from either internally or externally mixed
saline-Oxone particles was measure by reflectance-UV-Visible spectroscopy (Lambda
35, Perkin Elmer). The slit width and wavelength interval of spectral data were each 1
nm with a UV-Visible spectrum scan from 280 to 800 nm.
2.2 Monitoring of Acidity of Externally Mixed Saline-Oxone Aerosol
Acidity of externally mixed saline-Oxone aerosols was measured by collecting
particles on a TB (Sigma Aldrich) dyed filter and analyzing with reflective UV-Visible
spectroscopy (Jang et al. 2008). The filters were dyed with a TB solution prepared by
adding 2 mg of TB dye to a mixture of 5 mL water and 5 mL ethanol. The experimental
conditions and resulting data using UV-Visible spectroscopy are shown in Table 2-1.
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2.3 Measurement of Water Amount in Saline-Oxone Particles Using FTIR
Figure 2-2 shows the FTIR setup (Nicolet Magma 560, Nicolet) to monitor water
content in particles collected on a silicon window. Sodium chloride (Fisher, 99.5%),
saline, Oxone, and saline-Oxone (1:2 weight ratio) with or without buffer solutions were
atomized using a medical nebulizer. Sodium bicarbonate (Sigma-Aldrich, 99.7 %) and
phosphate (Sigma-Aldrich, 0.1mol/L) were used as buffers. The resulting NaCl, saline,
Oxone, and saline-Oxone particles were collected on a silicon FTIR window (13 × 2
mm, Sigma Aldrich) by impaction, dried directly on the window with clean air (Breathing
air, Airgas), and weighed using an analytical balance before and after particle collection
to measure the particle mass.
FTIR spectra of the impacted particles were obtained in the absorption mode
varying RH from 20% to 90% with the particle face of the silicon window exposed to the
air in the small flow chamber (0030-104, Thermo Spectra-Tech). The RH inside the flow
chamber was controlled by combining humid air from a water bubbler and dry air from a
dry air tank (Breathing air, Airgas) with a total air flow rate from 0.3 to 1.0 L/min.
Humidity and temperature were measured with an electronic thermohygrometer (Dwyer
series 485). Table 2-2 shows the experimental conditions and results for the FTIR
studies.
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Table 2-1. Experimental conditions to study aerosol reactivity and acidity using UV-Vis spectroscopy for the aerosol sample collected on the dyed filter with MY or TBa
aThe temperature and RH inside the Teflon chamber ranged from 22.8-27.4 C and 60.8-66.3 %. bThe aerosol composition is described based on the aerosol mass deposited on the filter. The original aqueous solution concentrations are 1% (W/V: weight/volume of water) for saline; 2% for Oxone solution; 2 % for buffer (sodium bicarbonate or phosphate buffer). cAerosol mass deposited on a dyed filter was measured using an analytical balance at the given laboratory RH (For internal mixture, aerosol mass was calculated from SMPS data (sampling flow rate ranged 10.1-11.5 L/min) and density of aerosol was 1.1 g/cm3. dSampled Oxone aerosol mass from Teflon chamber. eProton mass was calculated by equation 11. fN.A.: Not applicable. gThe experiments using the F1-F2 sampling system were carried out to confirm the oxidation ability of either aerosols or the active chlorine gases (e.g., HOCl and Cl2).
Dyed filter and aerosol system
Aerosol compositionb (weight ratio)
Sampling time (min)
Aerosol massc (µg)
Aerosol vol.conc. (nL/m3)
Moxone_aerosol
d
(µg)
HMass
e
(ng/m3)
MY external mixture
saline 5 9.00 331 23.51 N.A.f saline:buffer= 1:2 5 17.00 261 18.40 N.A. Oxone 1.5 - 500 10.60 N.A.
MY internal mixture
saline:Oxone=1:2 (F1-D-F2)
2 9.97 440 - N.A. 2.17 11.00 408 - N.A. 3 12.07 355 - N.A.
saline:Oxone=1:2 (F1-F2-F3)
2.50 10.15 321 - N.A. 3 10.57 317 - N.A.
saline:Oxone=1:2 (F1-F2)g
2 13.83 569 - N.A. 2.17 10.92 402 - N.A. 2.67 10.53 342 - N.A.
TB external mixture
saline 6 11.00 284 21.47 46.86
saline:buffer= 1:2 10.4 14.50 197 28.46 41.54
Table 2-2. Experimental conditions to monitor the water content in saline, Oxone, and saline-Oxone particles using FTIR and the estimated water amount in various particles in the two different RH at 20% and 70%.
Solutiona
(weight ratio) and composition
RH (%,lab)
Temp
( C)
Particle massb (μg)
Possible major aerosol constituents
Phase transition (Figure 3-5)
Mdry-particle at two different RHc (μg)
Mwater at two different RH (μg)
20% 70% 20% 70%
NaCl 52.0 25.5 55 NaCl ERH:55-57 DRH:83-87
36.7 36.7 0 93.0
saline salt- mole%: Na+ (41.94), Cl- (48.84), SO42- (2.53), Mg2+ (4.86), Ca2+ (0.94), K+ (0.89)
26.5 23.8 68 Na+, Cl-, SO42-, Mg2+
ERH:52-59 DRH:76-84
27.7 27.7 20.3 74.4
Oxone (2KHSO5 KHSO4 K2SO4)
19.7 19.4 51 K+ salts of SO5
2-, SO42-,
HSO5-, or HSO4
- No phase transition
30.4 30.4 17.2 34.9
Phosphate buffer (Na2HPO4)
49.3 26.0 65 Na2HPO4 No phase transition
10.5 10.5 N.A.d
45.4
Saline: Oxone = 1: 2 (no buffer)
38.0 22.5 53 Cl-; HOCl; Mg2+, K+ or Na+ salts of SO5
2-, SO42-,
HSO5-, or HSO4
-
No phase transition
17.0 17.0 21.6 30.1
Saline: Oxone: phosphate buffer (Na2HPO4) = 1: 2: 2.4
52.0 25.5 50 Cl-; HPO4
2-; HOCl; Mg2+, K+ or Na+ salts of SO5
2-, SO4
2-, HSO5-, or HSO4
-
No phase transition
27.8 27.8 6.1 26.0
Saline: Oxone: bicarbonate buffer (NaHCO3)= 1: 2: 2.4
53.6 25.0 58 Cl-; HOCl; Mg2+, K+ or Na+ salts of SO5
2-, SO42-,
HSO5-, or HSO4
-; CO2
ERH:51-55 DRH:74-78
32.5 32.5 6.0 84.0
aThe aerosol atomized from the aqueous solution of interest was impacted onto FTIR. The original aqueous solution concentrations are 1% (W/V: weight/volume of water) for saline; 2.5% for NaCl; 2% for Oxone solution; 2.4 % for buffer (sodium bicarbonate or phosphate buffer) bParticle mass deposited on a FTIR silicon window at the laboratory humidity condition. cSolute mass: Actual dry particle mass impacted on a silicon window corrected by relative humidity. dN.A.: Not applicable
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Figure 2-1. UV-Visible spectroscopy to monitor the evolution of active chlorine and
aerosol acidity in both internally and externally mixed aerosols. For externally mixed aerosol, Oxone particles were collected on the dyed filter containing the preexisting saline or saline-buffer particles. For the internally mixed aerosol, the saline-Oxone aerosol is sampled on the dyed filter using the different sampling systems (F1-F2-F3 and F1-D-F2).
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Figure 2-2. FTIR experimental setup to measure the water amount in oxidant particles.
The small flow chamber equipped with silicon and ZnSe FTIR windows was placed in the FTIR optical beam path in the transmission mode.
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CHAPTER 3 RESULTS AND DISCUSSION
3.1 Active Chlorine Formation and Its Oxidizing Effect
To evaluate the feasibility of oxidative reactions on a surface initiated by impacted
Oxone particles, the formation of active chlorine (HOCl) in the oxidant aerosol was
studied. Internally or externally mixed oxidant aerosol was collected on the MY-dyed
filter and monitored with reflective UV-Visible spectroscopy (Jang et al. 2008).
Unfortunately, MY exhibits spectral changes due to both reaction with active chlorine
(Sleiman et al. 2007) and change in proton concentrations ([H+], mol/L). The spectral
changes due to [H+] can be separated because UV absorption maxima of unprotonated-
MY and protonated-MY (HMY+) appear at 420 and 550 nm, respectively.
The absorption cross-section ratio for MY and HMY+ was determined by
measuring spectral shifts when acidic inorganic particles comprising sulfuric acid and
ammonium hydrogen sulfate were collected on a MY-dyed filter. The acidic inorganic
particle causes only spectral shifts as a result of [H+] changes. It is important to note
that the absorption at 550 nm was negligible before collection of acidic particles (i.e.,
MY was initially not protonated). Under the conditions of these experiments, a cross-
section ratio (σ420/ σ550) of 0.21 was measured using a least-squares curve fitting
method described previously (Jang et al. 2008). The absorption spectrum was fit to two
Gaussian functions with peak center frequency, peak absorbance, and peak width as
adjustable parameters.
A420,dye_only is the UV-Visible absorbance of the MY-dyed filter at 420 nm before
collection of particles, and A420,exp is that at 420 nm after collection of particles (acids
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and oxidants). The difference between A420,dye_only and A420,exp can be decoupled into
acidity effect and oxidation effect (∆A420,oxi) as shown in equation 3-1 below.
420420, 420, _ 420,exp 550,exp
550
oxi dye onlyA A A A
(3-1)
420,
420,
_
' oxioxiOxone aerosol
AA
M (3-2)
∆A420,oxi is normalized by the dry Oxone aerosol mass (MassOxone_aerosol). Figure 3-1
and 3-2 shows the ∆A’420,oxi values for the internally and externally mixed oxidant
aerosols, respectively. The gas-particle partitioning of HOCl generated in the internally
mixed saline-Oxone aerosol particles was investigated using the F1-F2-F3 and F1-D-F2
sampling setups (see Figure 2-1). The reaction time for the internally mixed saline-
Oxone aerosol (x-axis in Figure 3-1) is the total elapsed time from solution mixing to UV
scanning (solution mixing: 30-45 s, aerosol atomizing: 30-50 s, stabilizing of aerosol: 9-
10 min, aerosol sampling: 2-3 min, UV scanning: 1min 40 s).
The ∆A’420,oxi values for the F1 filters for both sampling setups (closed symbols)
were the same within the uncertainty of the measurement. Additionally, there was no
significant time dependence of the ∆A’420,oxi values for the F1 filters indicating that the
reaction between saline and Oxone was complete within 10 min and the oxidant
concentration was stable for at least 50 min. Such tendency was reconfirmed by the
additional three data sets using the F1-F2 sampling system.
The oxidation of MY in the F1 filter can be caused by both gas- and condensed-
phase HOCl. To estimate the fraction of MY oxidized by gas-phase HOCl in the F1 filter,
F2 and F3 filters were analyzed in the two different sampling setups. F2 in the F1-D-F2
sampling set-up exhibited negligible ∆A’420,oxi values indicating that oxidation on
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downstream filters without the denuder is caused primarily by gas-phase oxidants
because the K2CO3 coated denuder removes acidic gases (e.g., HOCl). Together with
the F2 and F3 results without the denuder, this conclusively demonstrates that some of
the oxidation on the F1 filter is caused by gas-phase oxidants.
To estimate the fractional amount of oxidation on F1 from gas-phase HOCl, the F2
and F3 filters were examined. As shown in Figure 3-1, ∆A’420,oxi values for both F2 and
F3 without the denuder are equivalent within the uncertainty of the measurements. This
indicates that the depletion of gas-phase HOCl across the filters was negligible;
otherwise, the oxidation of F3 would be significantly less than F2. We conclude that the
gas-phase HOCl exposure of F1 is equivalent to that of F2 and F3. The observed
oxidation of F2 and F3 was 30% of that for F1, and because the gas-phase HOCl
exposure was the same for all three filters, gas-phase HOCl oxidation of F1 accounts
for 30% of the total oxidation at our sampling and experimental conditions. Conversely,
particle-bound oxidant accounts for 70% of the observed oxidation of MY on the filter.
For the externally mixed particles, active chlorine formed when the Oxone particles
contacted either saline or saline-phosphate buffer particles on the dyed filter. Figure 3-2
shows the ∆A’420,oxi values obtained using equations 3-1 and 3-2 where the x-axis is the
time after collection of the Oxone particles. Overall, higher MY oxidation was observed
for Oxone particles collected in the presence of saline because saline promoted the
formation of active chlorine species. However, even Oxone particles collected in the
absence of saline showed some oxidizing capability. For example, the ∆A’420,oxi value of
the Oxone aerosol 30 min after the reaction began was 26-36% of that for the co-
deposited Oxone and saline or Oxone and saline-phosphate buffer particles.
25
The highest oxidation was observed for the co-collected saline and Oxone
particles. After the Oxone aerosol was collected on the dyed filter containing the
preexisting saline, nearly 90% of the oxidation progressed within 3 minutes compared to
oxidation within 33 minutes for our experimental duration. This result confirms that the
formation of active chlorine from the reaction between saline and Oxone rapidly
progresses. In the presence of phosphate buffer, only 28% of the oxidation in saline-
Oxone aerosol progressed within 10 minutes after the Oxone aerosol contacted the
dyed filter. This result shows that phosphate buffer retards the production rate of active
chlorine without reducing the maximum oxidizing capability for our experimental
duration.
3.2 Buffer Stability in Saline-Oxone Aerosol
Commonly used buffers such as bicarbonate and phosphate were internally mixed
with oxidant particles and monitored using FTIR to evaluate chemical stability in oxidant
aerosols. Figure 3-3 shows the FTIR spectra of each buffer compared to the subtracted
spectra ([spectrum of the saline-Oxone –buffer particles]-[spectrum of saline-Oxone
particles]). The subtracted FTIR spectrum for the particle system containing phosphate
buffer resembles the finger print of phosphate buffer alone, confirming the presence of
buffer in the saline-Oxone particles. However, the subtracted FTIR spectra for saline-
Oxone particles buffered with sodium bicarbonate does not show characteristic peaks at
700, 830, 1000, 1300-1400 cm-1 for bicarbonate buffer (Figure 3-3). This result indicates
that particles buffered with bicarbonate, while potentially at the correct pH, would lose
their buffering capacity since carbonic acid produced from the bicarbonate buffer rapidly
decomposes into carbon dioxide in the presence of water as shown in equations 3-3
and 3-4 (Thomas et al. 2000).
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3 3 2 3 2HCO H O H CO H O
(3-3)
2 3 2 2H CO H O CO (g)
(3-4)
Therefore, the stability of phosphate buffer makes it more favorable for
incorporation into the saline-Oxone aerosol.
3.3 Humidity Effect
Humidity influences kinetics of aerosol-phase reactions through two possible
mechanisms. First, the aerosol-phase water content, which is directly related to the
humidity, affects the reaction of saline-Oxone aerosol through phase transitions in the
particles. Second, the enrichment of inorganic constituents in particles due to the low
water content can influence kinetics of formation of active chlorine and/or
thermodynamic equilibria of inorganic species.
To monitor the humidity effect on saline-Oxone aerosol, FTIR integrated with a
small flow chamber capable of maintaining RH between 20% and 90% was used
(Figure 2-2). The intensity of the broad OH stretching band (centered at 3350 cm-1)
originating from the condensed-phase water in the impacted particles increases with
increasing RH (Criczo and Abbatt 2000; Kreidenweis et al. 2008). Figure 3-4 shows the
FTIR spectra of the NaCl particles at different RH levels: high RH (82%), middle RH
(60%), and low RH (7%).
Water uptake into NaCl particles has been studied previously, so it provides a
convenient reference for these measurements of particles impacted on a silicon
window. In our study, the observed DRH for the impacted NaCl particles was 83-87%
and the ERH was 55-57%. The resulting DRH and ERH values for the NaCl particles of
this study were slightly higher than those known in the literature (75-80% for DRH and
27
40-50 % for ERH) (Gao et al. 2007). A calibration curve (slope: 764.54 and intercept: -
5×10-16) for water content (Mwater, µg) in the impacted NaCl particles was obtained by
relating the FTIR absorbance (Abswater_3350) of the water peak at 3350 cm-1 at different
RH and the water mass fraction predicted from an inorganic thermodynamic model
(Nenes et al. 1998) (see Appendix A). M’water (µg/ µg) represents the particle-phase
water mass [Mwater, (µg)] divided by the sum of Mwater and dry-particle mass (Mdry-particle)
that is estimated from the difference between the total particle mass and the water mass
at a given laboratory RH and a given aerosol particle sample.
waterwater
dry particle water
MM
M M (3-5)
Table 2-2 and Figure 3-5 show the Mwater (µg) and M’water (µg/ µg) obtained for the
various particle compositions. In Figure 3-5, both impacted NaCl particles and impacted
saline particles show step changes in the water mass fraction indicating a phase
transition (ERH~ 55%). However, no dry aerosol was observed for the saline particles
which showed a large water mass fraction (M’water~ 0.4) in the particles even at 20% RH
compared with NaCl particles which showed an insignificant water mass fraction. This
difference is mainly caused by MgCl2 and MgSO4 present in saline particles (Tang et al.
1997; Zhao et al. 2006). MgSO4 promotes gel formation in concentrated liquid solutions
at low RH preventing crystallization of the particles. All other particle of this study exhibit
no apparent phase change (ERH) as RH was reduced to 20%. In fact, all impacted
oxidant particles still have significant water mass fractions suggesting that oxidant
aerosols are liquid and active chlorine species can form in saline-Oxone aerosol over
the entire humidity range of this study. Table 2-2 summarizes possible major aerosol
constituents from the saline-Oxone aerosol with and without buffer.
28
The saline-Oxone aerosol appeared to be least sensitive to changes in RH. The
calculated mole ratio of Cl- to HSO5- in the internally mixed saline-Oxone aerosol is 4.8
at a given composition indicating that the major aerosol constituents is still saline
although potassium and sodium sulfates are present in aerosol as reaction products.
Therefore, it is reasonable to conclude that the aerosol is not crystallized due to gel-like
saline constituents. However, it is unclear why saline-Oxone aerosol is least sensitive to
RH changes among oxidant mixture aerosols of this study. Phosphate buffer aerosol is
very hygroscopic; more than 43% of the total phosphate aerosol mass is water even at
35%. The saline-Oxone aerosol with phosphate buffer also showed no clear phase
transition possibly due to the effects of Na2HPO4 buffer and MgSO4 in saline.
3.4 Dynamics of Aerosol Acidity
Acidity influences the distribution of aqueous-phase chemical species (e.g., SO5-2
vs HSO5- in equation 1-1 and OCl- and HOCl in equation 1-3) which can affect the
oxidizing capability of the resulting aerosol. [H+] (mol/L) of saline-Oxone aerosol was
determined from the proton mass (MH+, ng/m3) measured by UV-Visible spectroscopy
(Jang et al. 2008) and Mwater measured by FTIR. To estimate the MH+ in saline-Oxone
aerosol, TB dye was selected as a pH indicator (Saikia and Dutta 2006) since it is
insensitive to active chlorine oxidants. A color change from yellow (λ= 450 nm) to red
(λ= 550 nm) occurs near pH 1.2-2.8 due to protonation of the TB dye (HTB+). The MH+
of the aerosol filter sample was calculated using the sampler air volume (Vair), UV-
Visible absorbance [A550,aerosol] at 550 nm for the protonated TB, and a calibration curve
for aerosol acidity. The calibration curve was obtained by relating the known proton
mass of inorganic acidic aerosol (MH+
_inorg) (NH4HSO4) (Jang et al. 2008) with A550,aerosol
29
corrected for spectral overlap from the absorbance of unprotonated TB (see Appendix
B).
550,278.63 aerosolH
air
AM
V (3-6)
MH+ calculated from equation 3-6 for the saline-Oxone aerosol (1:2 weight ratio)
and saline-Oxone-phosphate buffer (1:2:2 weight ratio) aerosol are shown in Table 2-1.
The [H+] of the saline-Oxone and the saline-Oxone with phosphate buffer aerosols were
obtained from MH+ (equation 3-6) and Mwater (equation 3-5).
, 55%
55%, 65%
[ ]H RH
RHaerosol RH water
Mass
HV V
(3-7)
where MassH+
,RH=55% represents the MH+ at laboratory RH (55%), Vaerosol,RH=65% is
the collected Oxone particle volume measure with a SMPS at the Teflon chamber RH
(65%), and ∆Vwater is the difference of the aerosol-phase water volume between
laboratory RH and Teflon chamber RH applied to oxidant aerosol. At our experimental
conditions, the obtained [H+] of saline-Oxone and saline-Oxone with phosphate buffer
aerosols using equation 3-7 are 0.17 mol/L and 0.24 mol/L, respectively, showing that
both aerosols are strongly acidic with pH value less than 0. The gas-phase HOCl
formed in aerosol would mostly evaporate to the gas phase due to its high volatility,
although HOCl produces Cl2 in acidic conditions (equation 1-5). However, as shown
above, the negligible oxidation effect on the F2 filter in the F1-D-F2 sampling system
using the K2CO3 coated denuder indicates that the main active chlorine compound
would be HOCl rather than Cl2.
30
0.00
0.01
0.02
0.03
0 10 20 30 40 50 60
A' 4
20
,oxi
Time (min)
F1 filter in F1-F2, F1-F2-F3, and F1-D-F2 sampling system
F2 filter in F1-F2 and F1-F2-F3 sampling system
F2 filter in F1-D-F2 sampling system
F3 filter in F1-F2-F3 sampling system
Figure 3-1. The ∆A’420,oxi obtained using different sampling systems (F1-F2-F3 and F1-
D-F2) for the internally mixed saline-Oxone aerosol after the Oxone was mixed with saline in the aqueous solution. Error bars are estimated from uncertainties in the sampling device, SMPS data, and UV-Visible absorbance.
31
0.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.0 27.5 30.0 32.50.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
Saline-Oxone aerosol
Saline-Oxone with phosphate buffer aerosol
Oxone aerosol only
A' 4
20
,oxi
Time (min)
Figure 3-2. Time profile of ∆A’420,oxi of the external mixture of Oxone, saline-Oxone,
saline-Oxone with phosphate buffer aerosol. Error bars were estimated from uncertainties in the sampling device, balance, SMPS data, and UV-Visible absorbance.
32
1800 1600 1400 1200 1000 800
0.0
0.2
0.4
0.6
0.8
1.0A
bso
rban
ce
Wavenumbers(cm-1)
Sodium bicarbonate
(SA+OX) with bicarbonate buffer-(SA+OX)
Phosphate buffer
(SA+OX) with phosphate buffer-(SA+OX)
Figure 3-3. FTIR spectra of the tested buffers (sodium bicarbonate and phosphate
buffer) and the subtracted FTIR spectra ([spectrum of Saline/Oxone/Buffer] – [spectrum of Saline/Oxone]).
33
4000 3000 2000 10000.00
0.05
0.10
0.15
0.20A
bso
rban
ce
wavenumber (cm-1)
82 RH(%)
61 RH(%)
57 RH(%)
7 RH(%)
water peak (3350cm-1)
Figure 3-4. FTIR spectra of NaCl particles impacted on silicon FTIR window at different humidity levels.
34
20 30 40 50 60 70 80 900.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9 Saline:Oxone:Phosphate Buffer (1:2:2.4) Saline:Oxone (1:2)
Phosphate Buffer Only
NaCl (ERH)
Oxone
SalineM' w
ate
r
Relative humidity (%)
Figure 3-5. The M’water of NaCl, saline, Oxone, and saline-Oxone aerosols as a function of decreasing humidity. Error bars were estimated from uncertainties in the FTIR absorbance at O-H stretching and balance.
35
CHAPTER 4 SUMMARY
Our results from the study of oxidizing capability of aerosol-phase active chlorine
species towards the organic dye show that the aerosolized saline-Oxone is a feasible
decontaminant for surfaces. The production rate of active chlorine species varies with
formulation of the oxidizing aerosol (i.e., presence and type of buffer) and aerosol
mixing type (e.g., internally or externally mixed aerosol). For example, when the fast
oxidation is required in the application such as examples shown by Delcomyn et al.
(2006), the externally mixed saline and Oxone particles without phosphate buffer would
be most profitable (Figure 3-2) among oxidant aerosols formulations investigated here.
When slow oxidation is needed, the externally mixed saline-Oxone aerosol with
phosphate buffer is appropriate due to retardation of active chlorine formation in aerosol
(Figure 3-2).
One significant problem with this approach is the partitioning of the aerosol-
originated oxidant to the gas phase. The low pH observed in the particles favors the
formation of HOCl which evaporates from the particles. Future research needs to
quantify the gas-particle portioning of HOCl and investigate formulations that result in
neutral pH.
36
APPENDIX A CALIBRATION CURVE FOR WATER CONTENT IN PARTICLES
NaCl particle was used as a standard particle to estimate the water content in
particles due to known thermodynamic property. The water mass in the NaCl particles
(MNaCl_water, μg) was obtained as follows:
_ _1
wNaCl water NaCl particle
w
fM M
f
Where fw is water mass fraction of the total NaCl particle (Nenes et al. 1998) and
MNaCl_particle (μg) is the NaCl particle mass collected on a silicon window. A calibration
curve for water content in the impacted NaCl particle was obtained using the FTIR
absorbance (Abswater_3350) (x-axis) at different RH (Figure 3-4) and the MNaCl_water (y-
axis). Obtained slope is 764.54 with intercept -5×10-16 and used to calculate the water
content in other particles (equation 3-5).
37
APPENDIX B CALIBRATION CURVE FOR AEROSOL ACIDITY
B.1 Experimental Procedures
A sampling filter (16mm, Gelman Sciences Pallflex, Type TX40HI20-WW) was
dyed with a solution (2mg of TB dye to a mixture of 5mL water and 5mL ethanol) for 10
minutes and dried naturally. A 2m3 Teflon chamber was flushed with clean air using two
clean air generators prior to experiment. The humidity of the chamber was controlled by
passing the clean dry air through a water bubbler. Inorganic aerosol was made from an
aqueous solution of ammonium hydrogen sulfate (0.01M) and sulfuric acid (0.01M) with
different mixing ratio and was atomized into the chamber using an atomizer. The
inorganic aerosol was collected from a Teflon chamber on a TB dyed filter using a pump
for 0.5-3 minutes at 13 L/min. The filter sample color changes associated with proton
concentrations in the aerosol sample were monitored by UV-Visible spectroscopy. Table
B-1 shows the experimental conditions and results.
B.2 Calibration Curve
Proton mass (MH+
_inorg) of inorganic acidic particles was calculated as follows:
_ 1000inorg inorgH HM f M
where Minorg is the total inorganic aerosol mass (µg) and fH+
is the proton mass
fraction of the total aerosol obtained from an inorganic thermodynamic model (Nenes et
al. 1998). Minorg is estimated as follows:
inorg inorg inorgM d V Q t
where dinorg is the density of aerosol (1.4 g/mL for our case), Vinorg is the aerosol
volume concentration obtained from the SMPS, Q is the volumetric air flow from a
sampling system, and t is the sampling time (see Table B-1). The calibration curve
38
(Figure B-1) for calculating available protons in aerosol was obtained by relating
MH+
_inorg (y-axis in Figure B-1) with A550,aerosol corrected for spectral overlap from the
absorbance of unprotonated TB (x-axis in Figure B-1). Obtained coefficient is 278.63
with R2=0.8493 and used to calculate the experimentally observed proton mass of the
aerosol on the filter (equation 3-6).
39
Table B-1. Experimental conditions and results to obtain calibration curve for aerosol acidity
aAS is sulfuric acid and AHS is ammonium hydrogen sulfate. bThe temperature and RH
in the lab ranged from 26-26.9 C and 46-50.6 %.. cSampling flow rate ranged 12.2-12.5 L/min and density of aerosol was 1.4 g/cm3.
y = 278.63x
R² = 0.8493
0
2
4
6
8
10
12
14
16
18
20
0 0.02 0.04 0.06 0.08
Corrected A550,aerosol
MH+_inorg (ng)
Figure B-2. Calibration curve for calculating aerosol acidity
Aerosol composition (volume ratio)
Temp( C)b RH(%) Sampling time (min)
Vinorg (nL/m3)
Minorg c
(ng)
SA:AHS=1:1a 26.3 46.8
3.25 177 10.07 3.28 123 6.95 1.92 126 4.12 0.75 113 1.47
SA:AHS=1:2 26.8 49.1
3.00 191 9.79 2.33 160 6.53
1.42 167 4.12
0.50 135 1.15
40
LIST OF REFERENCES
Adewuyi, Y.G., and Owusu, S.O. (2003). Aqueous Absorption and Oxidation of Nitric Oxide with Oxone for the Treatment of Tail Gases: Process Feasibility, Stoichiometry, Reaction Pathways, and Absorption Rate, Ind. Eng. Chem. Res. 42:4084-4100.
Chu, L.T., Leu, M.T., and Keyser, L.F. (1993). Heterogeneous Reactions of HOCl+HCl→Cl2+H2O and ClONO2+HCl→Cl2+HNO3 on Ice Surfaces at Polar Stratospheric Conditions, J. Phys. Chem. 97:12798-12804.
Cziczo, D.J., and Abbatt, J.P.D. (2000). Infrared Observations of the Response of NaCl, MgCl2, NH4HSO4, and NH4NO3 Aerosols to Changes in Relative Humidity from 298 to 238 K, J. Phys. Chem. A 104:2038-2047.
Delcomyn, C.A., Bushway, K.E., and Henley, M.V. (2006). Inactivation of Biological Agents using Neutral Oxone-chloride Solutions, Environ. Sci. & Technol. 40:2759-2764.
Eckhardt, C., Hefti, H., Meyer, H.R., and Weber, K. (1989). Stable Detergents Containing Optical Brighteners and Bleaching Agents, Eur. Pat. Appl. p. 7.
Eoga, Anthony B.J. (1985). Monopersulfate-containing Denture Cleansers, Eur. Pat. Appl. p. 20.
Feng, Y., Smith, D.W., and Bolton, J.R. (2007). Photolysis of Aqueous Free Chlorine Species (HOCl and OCl-) with 254 nm Ultraviolet Light, J. Environ. Eng. Sci. 6:277-284.
Gao, Y., Chen, S.B., and Yu, L.E. (2007). Efflorescence Relative Humidity of Airborne Sodium Chloride Particles: A Theoretical Investigation, Atmos. Environ. 41:2019-2023.
Gay, W.A. (1994). Sanitizer for Swimming Pools, Spas, and Hot Tubs, Cont.-in-part of U.S. 5,258,409 p. 9.
Gershenzon, M., Davidovits, P., Jayne, J.T., Kolb, C.E., and Worsnop, D.R. (2002). Rate Constant for the Reaction of Cl2(aq) with OH
-, J. Phys. Chem. A 106:7748-7754.
Jang, M., and Kamens, R.M. (2001). Characterization of Secondary Aerosol from the Photooxidation of Toluene in the Presence of NOx and 1-Propene, Environ. Sci. & Technol. 35:3626-3639.
Jang, M., Cao, G., and Paul, J. (2008). Colorimetric Particle Acidity Analysis of Secondary Organic Aerosol Coating on Submicron Acidic Aerosols, Aerosol Sci. & Technol. 42:409-420.
41
Jiang, Z. (1989). New Oxidation Method for Aldehydes to Carboxylic Acids by Oxone-acetone System, Zhongguo Yiyao Gongye Zazhi. 20:529-530.
Kennedy, R.J., and Stock, A.M. (1960). Oxidation of Organic Substances by Potassium Peroxymonosulfate, J. Org. Chem. 25:1901-1906.
Kreidenweis, S.M., Petters, M.D., and DeMott, P.J. (2008). Single-parameter Estimates of Aerosol Water Content, Environ. Res. Lett. 3:7.
Martin, P. (2005). A composition including Potassium Monopersulfate and Halogen Sepd.by a Barrier Film for Water Treatment in Aquatic Facilities, PCT Int.Appl. P. 16.
Massucci M., Clegg S.L., and Brimblemcombe, P. (1999). Equilibrium Partial Pressures, Thermodynamic Property of Aqueous and Solid Phases, and Cl2 Production from Aqueous HCl and HNO3 and Their Mixtures, J. Phys. Chem. A 103:4209-4226.
Nenes, A., Pandis, S.N., and Pilinis, C. (1998). ISOPROPIA, A New Thermodynamic Equilibrium Model for Multiphase Multicomponent Inorganic Aerosols, Aquatic Geochemistry 4:123-152.
Raber, E., and McGuire, R. (2002). Oxidative Decontamination of Chemical and Biological Warfare Agents using L-Gel, Journal of Hazardous Materials B 93:339-352.
Saikia, P.M., and Dutta, R.K. (2006). Acid-base Equilibria of Sulfonephthalein Dyes in Aqueous Polymer-surfactant Media, J. Surfactants & Detergents 9:39-45.
Schulze, A., Pagona, G., and Giannis, A. (2006). Oxone/sodium Chloride. A Simple and Efficient Catalytic System for the Oxidation of Alcohols to Symmetric Esters and Ketones, Synth. Commun. 36:1147-1156.
Sleiman, M., Vildozo, D., Ferronato, C., and Chovelon, J.M. (2007). Photocatalytic Degradation of Azo Dye Metanil Yellow: Optimization and Kinetic Modeling using a Chemometric Approach, Applied Catalysis, B: Environmental 77:1-11.
Tang, I.N., Tridico, A.C., and Fung, K.H. (1997). Thermodynamic and Optical Properties of Sea Salt Aerosols, J. Geophys. Res. 102:23269-23275.
Thomas, L., Christofer, T., Romano, T.K., Ingrid, K., Andreas, H., Erwin, M., and Klaus, R.L. (2000). On the Surprising Kinetic Stability of Carbonic Acid (H2CO3), Angew. Chem. Int. Ed. 5:892-894.
Travis, B.R., Sivakumar, M., Hollist, G.O., and Borhan, B. (2003). Facile Oxidation of Aldehyde to Acids and Esters with Oxone, Org. Lett. 25:1031-1034.
42
Wallace, W.H., Bushway, K.E., Miller, S.D., Delcomyn C.A., Renard J.J., and Henley M.V. (2005). Use of In Situ-Generated Dimethyldioxirane for Inactivation of Biological Agents, Environ. Sci. & Technol. 39:6288-6292.
Wang, L., Bassiri, M., Najafi, R., Najafi, K., Yang, J., Khosrovi, B., Hwong, W., Barati, E., Belisle, B., Celeri, C., and Robson, MC. (2007). Hypochlorous Acid as a Potential Wound Care Agent. Part I. Stabilized Hypochlorous Acid: A Component of the Inorganic Armamentarium of Innate Immunity, Journal of Burns and Wounds 6:65-79.
Webb, K.S., and Ruszkay, S.J. (1998). Oxidation of Aldehydes with Oxone in Aqueous Acetone, Tetrahedron 54:401-410.
Wojtowicz, J.A., Faust, J.P., and Brigano, F.A. (1983). Water Treatment of Swimming Pools, Spas, and Hot Tubs, Kirk-Othmer Encycl. Chem. Technol. 24:427-441.
Zhao, L.J., Zhang, Y.H., Wei, Z.F., Cheng, H., and Li, X.H. (2006). Magnesium Sulfate Aerosols Studied by FTIR Spectroscopy: Hygroscopic Properties, Supersaturated Structures, and Implications for Seawater Aerosols, J. Phys. Chem. A 110:951-958.
43
BIOGRAPHICAL SKETCH
Jaeyoun Jang graduated from Korea University in 2006. Her undergraduate major
was Civil Engineering and came to the University of Florida in 2008 to pursue her
master’s degree. She joined the aerosol research lab in the department of
Environmental Engineering Sciences. She worked on a project, ‘Characterization of and
decontamination by reactive saline aerosols’, and worked as a research assistant under
Dr. Myoseon Jang. She submitted a paper, ‘Formation of active chlorine oxidants in
saline-Oxone aerosol’, to Aerosol Science and Technology in 2010.