工业聚集区大气VOCs组成特征及对臭氧生成的影响

运用VOCs在线快速连续自动监测系统,检测了淄博市某工业集聚区大气中59种VOCs组分的浓度。结果表明:观测期间VOCs浓度平均值为(130.74±63.42)×10^-9(以体积分数计,全文同),其中,烷烃占41.17%±17.67%,烯烃占34.22%±23.79%,含硫有机物占12.20%±20.83%,芳香烃占6.70%±10.39%,炔烃占5.75%±6.49 %;烯烃类VOCs活性最高,尤其是乙烯、顺-2-丁烯和丙烯,其参与大气中光化学反应的能力较强。选取VOCs和O₃浓度不同的2个典型时段,用量子化学分子模拟对检出的含硫有机物与羟基自由基(·OH)的前线轨道能量差进行估算,发现甲硫醇、二甲基硫醚和二甲基二硫醚易与·OH发生链引发反应;分析2个时段VOCs组分对O₃生成的影响得出,当烯烃和芳香烃浓度不高时,因含硫有机物浓度增加,O₃浓度仍处于较高水平,含硫有机物是大气中O₃生成的主要贡献物。通过VOCs/NO_x判断敏感性发现,观测期间淄博市O₃生成对VOCs比较敏感,属于VOCs控制区。     

Experimental investigation on extinguishing performance of a novel nanocomposite for gaseous fires

A novel nanocomposite was synthesized by incorporating three different types of flame-retardants and its extinguishing performance was tested for gaseous fires. The nanocomposite consists of the inorganic magnesium hydroxide (MH) nanoparticles as the dominant component, the nitrogen-based melamine cyanurate (MCA), and the phosphorus-based ODOPB. The wet mixing, dry mixing, and ultrasonic agitation were employed in the preparation process to enhance the homogeneity of the nanocomposite. The prepared powders were characterized using a series of analytical instruments including X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravity analyzer (TGA), and differential scanning calorimeter (DSC). The efficiency of various samples in extinguishing gaseous fires was investigated in a lab-scale extinguishing system. The fire extinguishing tests indicated that the nanocomposite is considerably more effective in fire extinguishing than other powders in terms of extinction time and agent mass consumed. The fire extinction time of nanocomposite was 45.2% shorter than that of commercial ABC-MAP powder. Furthermore, the consumed amount of nanocomposite was 63.2% less than that of commercial powder. In addition, the order of extinguishing mass concentrations was as follows: the novel nanocomposite (103.7 g/m³) < MH/MCA (148.1 g/m³) < MH/ODOPB (155.6 g/m³) < MH (170.4 g/m³) < commercial ABC powder (281.5 g/m³) < MCA/ODOPB (384.1 g/m³). The fire suppression mechanisms of the nanocomposite were also discussed. It was inferred that the extinguishing mechanism of nanocomposite comprised of simultaneous chemical and physical inhibition actions involving chemical inhibition action, cooling action, and asphyxiation action. This study provides a promising attempt to gain benefits from the striking features of nanotechnology and flame-retardants in extinguishing gaseous fires.     

Pathway of the ozonation of 2,4,6-trichlorophenol in aqueous solution

The reaction mechanism and pathway of the ozonation of 2,4,6-trichlorophenol (2,4,6-TCP) in aqueous solution were investigated. The removal efficiency and the variation of H₂O₂, Cl⁻ formic acid, and oxalic acid were studied during the semi-batch ozonation experiments (continuous for ozone gas supply, fixed volume of water sample). The results showed that when there was no scavenger, the removal efficiency of 0.1 mmol/L 2,4,6-TCP could reach 99% within 6 min by adding 24 mg/L ozone. The reaction of molecular ozone with 2,4,6-TCP resulted in the formation of H₂O₂. The maximal concentration of H₂O₂ detected during the ozonation could reach 22.5% of the original concentration of 2,4,6-TCP. The reaction of ozone with H₂O₂ resulted in the generation of a lot of OH• radicals. Therefore, 2,4,6-TCP was degraded to formic acid and oxalic acid by ozone and OH• radicals together. With the inhibition of OH• radicals, ozone molecule firstly degraded 2,4,6-TCP to form chlorinated quinone, which was subsequently oxidized to formic acid and oxalic acid. Two reaction pathways of the degradation of 2,4,6-TCP by ozone and O₃/OH• were proposed in this study. Translated from Acta Scientiae Circumstantiae, 2005, 25(12): 1619–1623 [译自: 环境科学学报]     

Photooxidation of hydrochlorofluocarbons and hydrofluorocarbons initiated by OH radicals

ＰｈｏｔｏｏｘｉｄａｔｉｏｎｏｆｈｙｄｒｏｃｈｌｏｒｏｆｌｕｏｃａｒｂｏｎｓａｎｄｈｙｄｒｏｆｌｕｏｒｏｃａｒｂｏｎｓｉｎｉｔｉａｔｅｄｂｙＯＨｒａｄｉｃａｌｓ￥ＺｈｏｎｇＪｉｎｘｉａｎ；ＭｕＹｕｊｉｎｇ；ＹａｎｇＷｅｎｘｉａｎｇ（ＲｅｓｅａｒｃｈＣ...     

大气过氧自由基测量研究进展

过氧自由基是大气中重要的氧化剂 ,其浓度的测定对于深入理解大气化学过程具有重要意义。本文总结了二十多年的研究成果 ,论述了大气过氧自由基测量的研究进展 ,介绍了带基体分离的电子自旋共振技术、远红外及毫米波发射光谱技术、激光诱导荧光技术以及化学放大法等常用测量方法及测量结果 ,并展望其未来的发展。     

不同离子在CCl4引发自由基反应中的作用及其环境生物学意义

报道了一种简便的ＣＣ１４体外引发自由基反应的模型，以小鼠肝匀浆脂质过氧化产物丙二醛（ＭＤＡ）的ＯＤ５３２ｍｍ值（ＭＤＡ－ＯＤ５３２ｍｍ）作为测定自由基反应的间接指标，研究了Ｈｇ＾２＋、Ｍｎ＾２＋、Ｎｉ＾２＋、Ｃｒ＾３＋、ＳｅＯ３＾２－等离子和Ｓs２Ｏ３水溶液在ＣＣ１４引发自由基反应体系中的作用。结果表明：Ｍn＾２＋能显著抑制自由基的生成，Ｃr＾３＋有一定的抑制作用，而ＨgＴ＾２＋对自由基产生有明显促进     

Rate constants for the reaction of hydroxyl radicals with HFC-134a

ＲａｔｅｃｏｎｓｔａｎｔｓｆｏｒｔｈｅｒｅａｃｔｉｏｎｏｆｈｙｄｒｏｘｙｌｒａｄｉｃａｌｓｗｉｔｈＨＦＣ－１３４ａＺｈａｎｇＤｅｑｉａｎｇ，ＺｈｏｎｇＪｉｎｘｉａｎＲｅｓｅａｒｃｈＣｅｎｔｅｒｆｏｒＥｃｏＥｎｖｉｒｏｎｍｅｎｔａｌＳｃｉｅｎｃ...     

湿法回收砷碱渣中锑的工艺研究

本研究先以水浸实现砷碱渣中的砷锑分离,再对水浸渣进行盐酸浸出,得到了可作为工业原料氯化锑溶液.研究结果表明,在液固比为6∶1,温度40℃,浸出时间40 min的条件下,可使水浸过程中锑的浸出率低于3%,砷的浸出率达到99%;盐酸浸出中,控制酸浓度为1∶1,液固比10∶1,温度60℃,浸出时间30 min,能使锑的浸出率达到88%以上.经过水浸和盐酸浸出,锑的直接回收率为85.36%.     

大气环境中OH自由基测定

采用自旋捕集技术和电子自旋共振法结合测定大气环境中ＯＨ自由基，首先用自旋捕集剂将ＯＨ自由基捕集，生成比较稳定的自然旋加合物，，然后带回实验室处理测定，该法为开展大气光化学研究提供了一种采样方便，利于实测的方法，据３个采样点的实测结果表明，相对误差约为３５％，比文献所示结果略大。