Ozone（O3） is an important atmospheric oxidant. Black carbon（BC） particles released into the atmosphere undergo an aging process via O3 oxidation. O3-aged BC particles may change their uptake ability toward trace r...Ozone（O3） is an important atmospheric oxidant. Black carbon（BC） particles released into the atmosphere undergo an aging process via O3 oxidation. O3-aged BC particles may change their uptake ability toward trace reducing gases such as SO2 in the atmosphere,leading to different environmental and health effects. In this paper, the heterogeneous reaction process between O3-aged BC and SO2 was explored via in-situ diffuse reflectance infrared Fourier transform spectroscopy（DRIFTS）. Combined with ion chromatography（IC）,DRIFTS was used to qualitatively and quantitatively analyze the sulfate product. The results showed that O3-aged BC had stronger SO2 oxidation ability than fresh BC, and the reactive species/sites generated on the surface had an important role in the oxidation of SO2.Relative humidity or 254 nm UV（ultraviolet） light illumination enhanced the oxidation uptake of SO2 on O3-aged BC. The oxidation potentials of the BC particles were detected via dithiothreitol（DTT） assay. The DTT activity over BC was decreased in the process of SO2 reduction, with the consumption of oxidative active sites.展开更多
The dithiothreitol(DTT)assay is the most commonly used method to quantify the oxidative potential of fine particles.However,the reported DTT decay rates of carbon black(CB)materials vary greatly among different resear...The dithiothreitol(DTT)assay is the most commonly used method to quantify the oxidative potential of fine particles.However,the reported DTT decay rates of carbon black(CB)materials vary greatly among different researchers.This might have resulted from either the intrinsic toxicity of CB or the unsuitability of the DTT assay protocol for CB particles.In the current study,the protocol of the DTT assay for CB materials has been carefully evaluated.It was found that the dispersion degree of CB particles in water has a great influence on the DTT decay rate of CB materials.For CB particles(special black 4A(SB4A)and Printex U)and single-walled carbon nanotube tube(SWCNT),the DTT decay rate after sonication for 10 min became 4.2,4.6 and 1.7 times higher than that without sonication.The rate continued to grow as a function of ultrasound time up to 30 min of sonication.Although the concentration of soluble transition metals and surface oxygen-containing species such as carbonyls increased slightly with sonication,they had no significant effects on the measured DTT activity,while the increase in the dispersion degree of aggregates was found to play a vital role in the observed enhancement of the DTT decay rates for different CB materials.Based on our results,30 min of sonication is recommended for sample dispersion when measuring the DTT decay rate of CB materials.展开更多
基金the financial support provided by the National Natural Science Foundation of China(Nos.21277004,21190051,41121004)the Beijing Natural Science Foundation(No.8132035)+1 种基金the Fujitsu Laboratories Limited Foundation(No.k120400)the Special Fund of State Key Joint Laboratory of Environmental Simulation and Pollution Control(2015)
文摘Ozone（O3） is an important atmospheric oxidant. Black carbon（BC） particles released into the atmosphere undergo an aging process via O3 oxidation. O3-aged BC particles may change their uptake ability toward trace reducing gases such as SO2 in the atmosphere,leading to different environmental and health effects. In this paper, the heterogeneous reaction process between O3-aged BC and SO2 was explored via in-situ diffuse reflectance infrared Fourier transform spectroscopy（DRIFTS）. Combined with ion chromatography（IC）,DRIFTS was used to qualitatively and quantitatively analyze the sulfate product. The results showed that O3-aged BC had stronger SO2 oxidation ability than fresh BC, and the reactive species/sites generated on the surface had an important role in the oxidation of SO2.Relative humidity or 254 nm UV（ultraviolet） light illumination enhanced the oxidation uptake of SO2 on O3-aged BC. The oxidation potentials of the BC particles were detected via dithiothreitol（DTT） assay. The DTT activity over BC was decreased in the process of SO2 reduction, with the consumption of oxidative active sites.
基金financially supported by the National Natural Science Foundation of China (Nos. 91543109 and 41877306)the Fundamental Research Funds for the Central Universities (No. PT1907)Beijing University of Chemical Technology for financial support
文摘The dithiothreitol(DTT)assay is the most commonly used method to quantify the oxidative potential of fine particles.However,the reported DTT decay rates of carbon black(CB)materials vary greatly among different researchers.This might have resulted from either the intrinsic toxicity of CB or the unsuitability of the DTT assay protocol for CB particles.In the current study,the protocol of the DTT assay for CB materials has been carefully evaluated.It was found that the dispersion degree of CB particles in water has a great influence on the DTT decay rate of CB materials.For CB particles(special black 4A(SB4A)and Printex U)and single-walled carbon nanotube tube(SWCNT),the DTT decay rate after sonication for 10 min became 4.2,4.6 and 1.7 times higher than that without sonication.The rate continued to grow as a function of ultrasound time up to 30 min of sonication.Although the concentration of soluble transition metals and surface oxygen-containing species such as carbonyls increased slightly with sonication,they had no significant effects on the measured DTT activity,while the increase in the dispersion degree of aggregates was found to play a vital role in the observed enhancement of the DTT decay rates for different CB materials.Based on our results,30 min of sonication is recommended for sample dispersion when measuring the DTT decay rate of CB materials.
