In this work, contact angle measurements for soot samples collected from a kerosene lantern, wood-burning fireplace, and municipal bus engine exhaust lines are reported. Contact angles for both freshly collected soot ...In this work, contact angle measurements for soot samples collected from a kerosene lantern, wood-burning fireplace, and municipal bus engine exhaust lines are reported. Contact angles for both freshly collected soot and samples treated with various doses of O3 (g), HNO3 (g), and H2SO4 (g) are considered. Use of a literature method has allowed estimation of the enthalpy of immersion (Himm) for the soot samples based on contact angle observed. Contact angles for freshly collected soot were 65 - 110 deg. indicating its hydrophobic nature. Chemical processing of soot usually resulted in smaller contact angles and large increases in immersion enthalpy. However, the dose of ozone, nitric or sulfuric acid vapor required to achieve alteration of the soot surface appeared to be considerably larger than that expected to be experienced by authentic atmospheric samples during the soot particles lifetime. The most significant variability of soot contact angle was observed for the municipal bus exhaust samples, suggesting that combustion chemistry may significantly affect wetting behavior.展开更多
Phenolic compounds are emitted into earth’s atmosphere through industry and biomass burning events. These compounds may react in the gas or particle phase to form additional airborne pollutants. In this work, the aqu...Phenolic compounds are emitted into earth’s atmosphere through industry and biomass burning events. These compounds may react in the gas or particle phase to form additional airborne pollutants. In this work, the aqueous phase chemical reactions of syringol, guaiacol, and catechol were studied in the presence of nitrate (NO-3 ) or nitrite ( NO-2) with and without UV illumination. The reactions were found to yield light absorbing products and electrospray ionization mass spectrometry (ESI-MS) experiments indicate some of the compounds formed may be the nitrated analogues of the starting organic compounds. However, infrared absorption data suggests the reaction products are composed of a complicated mixture. This suggests additional reactions occur simultaneously in solution. Treatment of the isolated reaction products with ozone (O3) suggest they are unstable and will eventually chemically decompose if/when formed in the atmosphere.展开更多
文摘In this work, contact angle measurements for soot samples collected from a kerosene lantern, wood-burning fireplace, and municipal bus engine exhaust lines are reported. Contact angles for both freshly collected soot and samples treated with various doses of O3 (g), HNO3 (g), and H2SO4 (g) are considered. Use of a literature method has allowed estimation of the enthalpy of immersion (Himm) for the soot samples based on contact angle observed. Contact angles for freshly collected soot were 65 - 110 deg. indicating its hydrophobic nature. Chemical processing of soot usually resulted in smaller contact angles and large increases in immersion enthalpy. However, the dose of ozone, nitric or sulfuric acid vapor required to achieve alteration of the soot surface appeared to be considerably larger than that expected to be experienced by authentic atmospheric samples during the soot particles lifetime. The most significant variability of soot contact angle was observed for the municipal bus exhaust samples, suggesting that combustion chemistry may significantly affect wetting behavior.
文摘Phenolic compounds are emitted into earth’s atmosphere through industry and biomass burning events. These compounds may react in the gas or particle phase to form additional airborne pollutants. In this work, the aqueous phase chemical reactions of syringol, guaiacol, and catechol were studied in the presence of nitrate (NO-3 ) or nitrite ( NO-2) with and without UV illumination. The reactions were found to yield light absorbing products and electrospray ionization mass spectrometry (ESI-MS) experiments indicate some of the compounds formed may be the nitrated analogues of the starting organic compounds. However, infrared absorption data suggests the reaction products are composed of a complicated mixture. This suggests additional reactions occur simultaneously in solution. Treatment of the isolated reaction products with ozone (O3) suggest they are unstable and will eventually chemically decompose if/when formed in the atmosphere.
