Oxidative Potential of Semi-Volatile and Non Volatile Particulate Matter (PM) from Heavy-Duty Vehicles Retrofitted with Emission Control Technologies
Oxidative Potential of Semi-Volatile and Non Volatile Particulate Matter (PM) from Heavy-Duty Vehicles Retrofitted with Emission Control Technologies
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DOI：
10.1021/es9000592
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发表时间：
2009-05-15
影响因子：
11.4
通讯作者：
Sioutas, Constantinos
中科院分区：
文献类型：
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作者：
Biswas, Subhasis;Verma, Vishal;Sioutas, Constantinos
先进的柴油车排气后处理装置在控制半挥发性物质方面不如难处理PM组分有效。本研究调查了与“基线”车辆（无任何控制装置）相比，采用六种改装技术（基于钒和沸石的选择性催化还原（V-SCRT，Z-SCRT）、连续再生技术（CRT）、催化DPX过滤器、催化连续再生捕集器（CCRT）和非催化Horizon过滤器）的车辆PM的氧化电位（OP）。车辆在底盘测功机上在三种驾驶条件下进行测试，即，巡航、瞬时城市测功机驾驶计划（ODDS）和怠速。二硫苏糖醇（DTT）的消耗率，OP的替代措施之一，测定在环境温度和升高的温度下收集的PM样品（热剥半挥发性物质）。控制装置使每辆车行驶距离的OP减少了60- 98%。然而，每单位质量的PM的氧化电位对于Horizon是最高的，其次是CRT、DPX -Idle、SCRT和基线车辆。观察到采用改装技术的车辆（具有显著半挥发性部分的PM）的热裸露PM的OP显著降低（50-100%），而基线车辆（具有微不足道的半挥发性部分）排放的颗粒物未表现出任何可测量的氧化活性变化。这表明，颗粒的半挥发性部分是更氧化的性质比耐火颗粒进一步支持以前的隧道和环境研究的结论，表明PM氧化活性随着大气稀释度的增加而下降。所有物种之间进行的相关性分析，表明OP是中度相关（R = 0.76）与有机碳（OC）和强烈相关（R = 0.94）与水溶性有机碳（WSOC）。
Advanced exhaust after-treatment devices for diesel vehicles are less effective in controlling semivolatile species than the refractory PM fractions. This study investigates the oxidative potential (OP) of PM from vehicles with six retrofitted technologies (vanadium and zeolite based selective catalytic reduction (V-SCRT, Z-SCRT), Continuously regenerating technology (CRT), catalyzed DPX filter, catalyzed continuously regenerating trap (CCRT), and uncatalyzed Horizon filter) in comparison to a "baseline" vehicle (without any control device). Vehicles were tested on a chassis dynamometer at three driving conditions, i.e., cruise, transient urban dynamometer driving schedule (ODDS), and idle. The consumption rate of dithiothreitol (DTT), one of the surrogate measures of OP, was determined for PM samples collected at ambient and elevated temperatures (thermally denuded of semivolatile species). Control devices reduced the OP expressed per vehicle distance traveled by 60-98%. The oxidative potential per unit mass of PM however, was highest for the Horizon followed by CRT, DPX -Idle, SCRTs, and baseline vehicles. Significant reduction in OP (by 50-100%) was observed for thermally denuded PM from vehicles with retrofitted technologies (PM with significant semivolatile fraction), whereas particles emitted by the baseline vehicle (with insignificant semivolatile fraction) did not demonstrate any measurable changes in oxidative activity. This suggests that the semivolatile fraction of particles are far more oxidative in nature than refractory particles-a conclusion further supported by previous tunnel and ambient studies, demonstrating a decline in PM oxidative activity with increasing atmospheric dilution. Correlation analysis performed between all the species, showed that OP is moderately associated (R = 0.76) with organic carbon (OC) and strongly associated (R = 0.94) with the water-soluble organic carbon (WSOC).