Liquid–liquid phase separation and viscosity within secondary organic aerosol generated from diesel fuel vapors
<p>Information on liquid–liquid phase separation (LLPS) and viscosity (or diffusion) within secondary organic aerosol (SOA) is needed to improve predictions of particle size, mass, reactivity, and cloud nucleating properties in the atmosphere. Here we report on LLPS and viscosities within SOA...
| Main Authors: | , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-10-01
|
| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/19/12515/2019/acp-19-12515-2019.pdf |
| id |
doaj-b52d5d50ee5748539c15c16655af41ec |
|---|---|
| record_format |
Article |
| collection |
DOAJ |
| language |
English |
| format |
Article |
| sources |
DOAJ |
| author |
M. Song M. Song A. M. Maclean Y. Huang N. R. Smith S. L. Blair J. Laskin A. Laskin W.-S. W. DeRieux Y. Li M. Shiraiwa S. A. Nizkorodov A. K. Bertram |
| spellingShingle |
M. Song M. Song A. M. Maclean Y. Huang N. R. Smith S. L. Blair J. Laskin A. Laskin W.-S. W. DeRieux Y. Li M. Shiraiwa S. A. Nizkorodov A. K. Bertram Liquid–liquid phase separation and viscosity within secondary organic aerosol generated from diesel fuel vapors Atmospheric Chemistry and Physics |
| author_facet |
M. Song M. Song A. M. Maclean Y. Huang N. R. Smith S. L. Blair J. Laskin A. Laskin W.-S. W. DeRieux Y. Li M. Shiraiwa S. A. Nizkorodov A. K. Bertram |
| author_sort |
M. Song |
| title |
Liquid–liquid phase separation and viscosity within secondary organic aerosol generated from diesel fuel vapors |
| title_short |
Liquid–liquid phase separation and viscosity within secondary organic aerosol generated from diesel fuel vapors |
| title_full |
Liquid–liquid phase separation and viscosity within secondary organic aerosol generated from diesel fuel vapors |
| title_fullStr |
Liquid–liquid phase separation and viscosity within secondary organic aerosol generated from diesel fuel vapors |
| title_full_unstemmed |
Liquid–liquid phase separation and viscosity within secondary organic aerosol generated from diesel fuel vapors |
| title_sort |
liquid–liquid phase separation and viscosity within secondary organic aerosol generated from diesel fuel vapors |
| publisher |
Copernicus Publications |
| series |
Atmospheric Chemistry and Physics |
| issn |
1680-7316 1680-7324 |
| publishDate |
2019-10-01 |
| description |
<p>Information on liquid–liquid phase separation (LLPS) and viscosity (or
diffusion) within secondary organic aerosol (SOA) is needed to improve
predictions of particle size, mass, reactivity, and cloud nucleating
properties in the atmosphere. Here we report on LLPS and viscosities within
SOA generated by the photooxidation of diesel fuel vapors. Diesel fuel
contains a wide range of volatile organic compounds, and SOA generated by
the photooxidation of diesel fuel vapors may be a good proxy for SOA from
anthropogenic emissions. In our experiments, LLPS occurred over the relative
humidity (RH) range of <span class="inline-formula">∼70</span> % to <span class="inline-formula">∼100</span> %,
resulting in an organic-rich outer phase and a water-rich inner phase. These
results may have implications for predicting the cloud nucleating properties
of anthropogenic SOA since the presence of an organic-rich outer phase at
high-RH values can lower the supersaturation with respect to water required
for cloud droplet formation. At <span class="inline-formula">≤10</span> % RH, the viscosity was <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>≥</mo><mn mathvariant="normal">1</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mn mathvariant="normal">8</mn></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="46pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="d3becb04dea2544bfec575e486a5f107"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-12515-2019-ie00001.svg" width="46pt" height="14pt" src="acp-19-12515-2019-ie00001.png"/></svg:svg></span></span> Pa s, which corresponds to roughly the viscosity of tar
pitch. At 38 %–50 % RH, the viscosity was in the range of <span class="inline-formula">1×10<sup>8</sup></span> to <span class="inline-formula">3×10<sup>5</sup></span> Pa s. These measured viscosities are
consistent with predictions based on oxygen to carbon elemental ratio (<span class="inline-formula">O:C</span>)
and molar mass as well as predictions based on the number of carbon,
hydrogen, and oxygen atoms. Based on the measured viscosities and the
Stokes–Einstein relation, at <span class="inline-formula">≤10</span> % RH diffusion coefficients of
organics within diesel fuel SOA is <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>≤</mo><mn mathvariant="normal">5.4</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">17</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="65pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="81f85a19804ee0bbb25c62f30c9dfc4e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-12515-2019-ie00002.svg" width="65pt" height="14pt" src="acp-19-12515-2019-ie00002.png"/></svg:svg></span></span> cm<span class="inline-formula"><sup>2</sup></span> s<span class="inline-formula"><sup>−1</sup></span> and the mixing time of organics within 200 nm diesel fuel SOA
particles (<span class="inline-formula"><i>τ</i><sub>mixing</sub></span>) is 50 h. These small diffusion coefficients
and large mixing times may be important in laboratory experiments, where SOA
is often generated and studied using low-RH conditions and on timescales of
minutes to hours. At 38 %–50 % RH, the calculated organic diffusion
coefficients are in the range of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">5.4</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">17</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="55pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="b8aaddae8a73d2d23727b0f38112daf7"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-12515-2019-ie00003.svg" width="55pt" height="14pt" src="acp-19-12515-2019-ie00003.png"/></svg:svg></span></span> to <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">1.8</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">13</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="55pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="bfcea12d119b18040d27e13eb2907160"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-12515-2019-ie00004.svg" width="55pt" height="14pt" src="acp-19-12515-2019-ie00004.png"/></svg:svg></span></span> cm<span class="inline-formula"><sup>2</sup></span> s<span class="inline-formula"><sup>−1</sup></span> and calculated <span class="inline-formula"><i>τ</i><sub>mixing</sub></span> values are
in the range of <span class="inline-formula">∼0.01</span> h to <span class="inline-formula">∼50</span> h. These values
provide important constraints for the physicochemical properties of
anthropogenic SOA.</p> |
| url |
https://www.atmos-chem-phys.net/19/12515/2019/acp-19-12515-2019.pdf |
| work_keys_str_mv |
AT msong liquidliquidphaseseparationandviscositywithinsecondaryorganicaerosolgeneratedfromdieselfuelvapors AT msong liquidliquidphaseseparationandviscositywithinsecondaryorganicaerosolgeneratedfromdieselfuelvapors AT ammaclean liquidliquidphaseseparationandviscositywithinsecondaryorganicaerosolgeneratedfromdieselfuelvapors AT yhuang liquidliquidphaseseparationandviscositywithinsecondaryorganicaerosolgeneratedfromdieselfuelvapors AT nrsmith liquidliquidphaseseparationandviscositywithinsecondaryorganicaerosolgeneratedfromdieselfuelvapors AT slblair liquidliquidphaseseparationandviscositywithinsecondaryorganicaerosolgeneratedfromdieselfuelvapors AT jlaskin liquidliquidphaseseparationandviscositywithinsecondaryorganicaerosolgeneratedfromdieselfuelvapors AT alaskin liquidliquidphaseseparationandviscositywithinsecondaryorganicaerosolgeneratedfromdieselfuelvapors AT wswderieux liquidliquidphaseseparationandviscositywithinsecondaryorganicaerosolgeneratedfromdieselfuelvapors AT yli liquidliquidphaseseparationandviscositywithinsecondaryorganicaerosolgeneratedfromdieselfuelvapors AT mshiraiwa liquidliquidphaseseparationandviscositywithinsecondaryorganicaerosolgeneratedfromdieselfuelvapors AT sanizkorodov liquidliquidphaseseparationandviscositywithinsecondaryorganicaerosolgeneratedfromdieselfuelvapors AT akbertram liquidliquidphaseseparationandviscositywithinsecondaryorganicaerosolgeneratedfromdieselfuelvapors |
| _version_ |
1725065622470000640 |
| spelling |
doaj-b52d5d50ee5748539c15c16655af41ec2020-11-25T01:35:53ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242019-10-0119125151252910.5194/acp-19-12515-2019Liquid–liquid phase separation and viscosity within secondary organic aerosol generated from diesel fuel vaporsM. Song0M. Song1A. M. Maclean2Y. Huang3N. R. Smith4S. L. Blair5J. Laskin6A. Laskin7W.-S. W. DeRieux8Y. Li9M. Shiraiwa10S. A. Nizkorodov11A. K. Bertram12Department of Earth and Environmental Sciences, Chonbuk National University, Jeollabuk-do, 54896, Republic of KoreaDepartment of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, CanadaDepartment of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, CanadaDepartment of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, CanadaDepartment of Chemistry, University of California Irvine, Irvine, CA 92697, USADepartment of Chemistry, University of California Irvine, Irvine, CA 92697, USADepartment of Chemistry, Purdue University, West Lafayette, IN 47907, USADepartment of Chemistry, Purdue University, West Lafayette, IN 47907, USADepartment of Chemistry, University of California Irvine, Irvine, CA 92697, USADepartment of Chemistry, University of California Irvine, Irvine, CA 92697, USADepartment of Chemistry, University of California Irvine, Irvine, CA 92697, USADepartment of Chemistry, University of California Irvine, Irvine, CA 92697, USADepartment of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada<p>Information on liquid–liquid phase separation (LLPS) and viscosity (or diffusion) within secondary organic aerosol (SOA) is needed to improve predictions of particle size, mass, reactivity, and cloud nucleating properties in the atmosphere. Here we report on LLPS and viscosities within SOA generated by the photooxidation of diesel fuel vapors. Diesel fuel contains a wide range of volatile organic compounds, and SOA generated by the photooxidation of diesel fuel vapors may be a good proxy for SOA from anthropogenic emissions. In our experiments, LLPS occurred over the relative humidity (RH) range of <span class="inline-formula">∼70</span> % to <span class="inline-formula">∼100</span> %, resulting in an organic-rich outer phase and a water-rich inner phase. These results may have implications for predicting the cloud nucleating properties of anthropogenic SOA since the presence of an organic-rich outer phase at high-RH values can lower the supersaturation with respect to water required for cloud droplet formation. At <span class="inline-formula">≤10</span> % RH, the viscosity was <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>≥</mo><mn mathvariant="normal">1</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mn mathvariant="normal">8</mn></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="46pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="d3becb04dea2544bfec575e486a5f107"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-12515-2019-ie00001.svg" width="46pt" height="14pt" src="acp-19-12515-2019-ie00001.png"/></svg:svg></span></span> Pa s, which corresponds to roughly the viscosity of tar pitch. At 38 %–50 % RH, the viscosity was in the range of <span class="inline-formula">1×10<sup>8</sup></span> to <span class="inline-formula">3×10<sup>5</sup></span> Pa s. These measured viscosities are consistent with predictions based on oxygen to carbon elemental ratio (<span class="inline-formula">O:C</span>) and molar mass as well as predictions based on the number of carbon, hydrogen, and oxygen atoms. Based on the measured viscosities and the Stokes–Einstein relation, at <span class="inline-formula">≤10</span> % RH diffusion coefficients of organics within diesel fuel SOA is <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>≤</mo><mn mathvariant="normal">5.4</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">17</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="65pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="81f85a19804ee0bbb25c62f30c9dfc4e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-12515-2019-ie00002.svg" width="65pt" height="14pt" src="acp-19-12515-2019-ie00002.png"/></svg:svg></span></span> cm<span class="inline-formula"><sup>2</sup></span> s<span class="inline-formula"><sup>−1</sup></span> and the mixing time of organics within 200 nm diesel fuel SOA particles (<span class="inline-formula"><i>τ</i><sub>mixing</sub></span>) is 50 h. These small diffusion coefficients and large mixing times may be important in laboratory experiments, where SOA is often generated and studied using low-RH conditions and on timescales of minutes to hours. At 38 %–50 % RH, the calculated organic diffusion coefficients are in the range of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">5.4</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">17</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="55pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="b8aaddae8a73d2d23727b0f38112daf7"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-12515-2019-ie00003.svg" width="55pt" height="14pt" src="acp-19-12515-2019-ie00003.png"/></svg:svg></span></span> to <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">1.8</mn><mo>×</mo><msup><mn mathvariant="normal">10</mn><mrow><mo>-</mo><mn mathvariant="normal">13</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="55pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="bfcea12d119b18040d27e13eb2907160"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-12515-2019-ie00004.svg" width="55pt" height="14pt" src="acp-19-12515-2019-ie00004.png"/></svg:svg></span></span> cm<span class="inline-formula"><sup>2</sup></span> s<span class="inline-formula"><sup>−1</sup></span> and calculated <span class="inline-formula"><i>τ</i><sub>mixing</sub></span> values are in the range of <span class="inline-formula">∼0.01</span> h to <span class="inline-formula">∼50</span> h. These values provide important constraints for the physicochemical properties of anthropogenic SOA.</p>https://www.atmos-chem-phys.net/19/12515/2019/acp-19-12515-2019.pdf |