二次有机气溶胶中二羰基化合物的研究进展

二次有机气溶胶的形成是大气环境化学的研究热点。二羰基化合物对二次有机气溶胶形成具有重要的研究意义。由于二羰基化合物在液相中发生聚合反应,在液相中的分配大于Henry定律的预测值,影响二次有机气溶胶的形成。通过二羰基化合物乙二醛和甲基乙二醛在大气中光氧化和异相反应的研究,评述了二羰基化合物对二次有机气溶胶形成的研究发展。     

种子气溶胶对甲苯光氧化生成二次有机气溶胶的生长影响

在烟雾腔内进行了羟基自由基启动的甲苯光氧化生成二次有机气溶胶的实验.通过向烟雾腔内添加硫酸铵、硝酸铵、硅酸钠和氯化钙4种不同的种子气溶胶,考察它们对二次有机气溶胶形成的影响.结果表明:种子气溶胶的浓度越低,越有利于二次有机气溶胶的生成;在反应开始阶段,种子气溶胶对二次有机气溶胶的形成起促进作用,随着反应时间的增长,反而起阻止作用:在相同的种子气溶胶浓度下,硅酸钠和硝酸铵对二次有机气溶胶的形成的影响几乎相同;4种种子气溶胶对甲苯氧化生成的二次有机气溶胶的生长影响顺序为:氯化钙》硝酸铵、硅酸钠》硫酸铵.     

甲苯与氯原子光氧化产生二次有机气溶胶粒子实时探测研究

在烟雾腔内,用紫外光照射甲苯、氯气、一氧化氮和空气的混合物,启动甲苯和氯原子的光氧化反应和一系列的后续反应,产生非挥发性和半挥发性有机化合物.半挥发性有机化合物可以在气态和粒子态之间进行分配,产生二次有机气溶胶粒子.用实验室自制的气溶胶飞行时间质谱仪实时测量这些粒子产物的分子成分和粒径分布,并初步探讨了这些组分的可能反应机理.     

石化行业VOCs对二次有机气溶胶的贡献及估算方法

VOCs是石化行业排放的特征污染物,也是大气细颗粒物PM2.5的重要前体污染物。通过对石化行业典型VOCs排放污染源进行归类解析,将其来源细分为原料、产品装卸过程等9种工艺过程;得出烷烃、烯烃、芳香族化合物是石化行业排放的几种重要的VOCs,并分别对这几类VOCs生成SOA的转化机理进行归纳,并且总结了几种重要的SOA生成潜势定量估算方法;最后对石化行业VOCs与周围大气PM2.5的相关性研究发展提出了建议。     

气溶胶飞行时间质谱仪分析间-二甲苯光氧化颗粒相产物

在自制的烟雾腔内,用紫外光照射间-二甲苯、亚硝酸甲酯、一氧化氮和清洁空气的混合物,可以启动间-二甲苯和羟基自由基(OH)的光氧化反应和一系列的后续反应,产生非挥发性和半挥发性有机化合物.半挥发性有机化合物可以在气态和粒子态之间进行分配,产生二次有机气溶胶粒子.采用实时测量气溶胶粒子粒径大小和化学成分的气溶胶飞行时间质谱仪快速、实时地测量了这些粒子的尺度、它们的分子成分和粒径分布.通过化学分析,得到酚、醛、酮和羧酸等重要的间-二甲苯光氧化产物,为讨论间-二甲苯光氧化反应机理提供了新的信息.     

大气微粒二次有机碳形成特性研究

悬浮微粒为空气污染主要项目之一,且PM1(气动直径小于1 μm之微粒)为引起呼吸道各种病变的最主要污染,因此了解大气环境悬浮微粒之来源与特性,是保护人民健康及空气品质的首要工作.本研究分别于高雄市小港(都会区)与台东县太麻里(郊区)进行大气悬浮微粒测定,量测大气悬浮微粒中PM1及PM10之质量浓度与分布,并利用元素分析仪分析微粒中之有机碳(organic carbon,OC)与元素碳(elemental carbon,EC)含量.分析研究期间所得样本结果显示,都会区PM1及PM10有机碳(OC)及元素碳(EC)之浓度均较郊区高,且OC浓度又比EC高;而郊区PM1及PM10之OC及EC之含量较都会区之含量高.若以最小比值估计法OCsec=OCtotal-(OC/EC)minxEC,可估算都会区大气微粒PM1及PM10有机碳成分中约有30.4%及33.0%,郊区之PM1及PM10有机碳成分中则约有40.1%及17.6%,为挥发性有机物气固相传输所形成之二次有机碳组成,结果显示较细微粒(PM1)二次有机碳之含量较高,且郊区大气中亦有相当比例之二次有机碳组成.     

锂离子二次电池有机电解液研究进展

综述了目前国内外锂离子二次电池用有机电解液的发展状况。从新型导电锂盐的合成,高介电常数有机溶剂的配制,寻找新型电解液添加剂3个方面分析了如何改善和提高有机电解液的性能。     

二次盐水中总有机碳的测定

介绍采用Multi n/c-2100检测仪,利用高温催化燃烧氧化-非色散红外探测原理测定盐水中的总有机碳的方法以及测定中的注意事项。     

有机碳源对微生物代谢所致水体黑臭现象形成的影响机制

黑臭水体已成为最亟需解决的城市水环境问题。有机污染是导致水体黑臭的关键因素,但有机碳源对黑臭现象形成的影响机制尚不明晰。文中以淀粉为有机碳源、实际黑臭水样为菌液,在封闭静态微生态系统中模拟水样黑臭现象形成过程。试验结果表明,水样黑臭现象形成受微生物驱动,适宜的菌液比为1∶250,在该菌液比下有机碳源[淀粉,以总有机碳(TOC)计]质量浓度≥100 mg/L时,水样出现黑臭现象。皮尔逊相关性分析表明水样黑臭程度(色度和臭阈值)与有机碳源浓度显著正相关,而溶解氧(DO)与有机碳源浓度极显著负相关(p<0.01,r²=0.98),说明有机碳源是水体黑臭的重要因素。通过测定水样中DO、Fe²⁺、S^2-和FeS浓度变化,表明试验条件下有机碳源对水样黑臭现象形成的影响机制是微生物分解有机碳源消耗水中大量DO,导致水样在缺氧还原状态下易产生FeS和H₂S等致黑、致臭物质。     

在光顺—反异构化反应中的“呼拉”扭转：有机体系

文献中有关有机分子在介质中的光顺－反异构化反应有很多的报道。研究的结果表明：所有的例子都存在着“呼拉”扭转反应机制。这一结论是与曾报道过的有关体积守恒理论相一致。所以，这种介质的包围将对溶液中底物的光顺－反异构化反应产生很大的影响（这也是超分子作用之一）。     

单晶态α-Fe_2O_3纳米管的制备及其形成机理探讨

在非水溶剂正丁醇中,采用简单的有机溶剂回流加热法,在不加任何表面活性剂和分散剂的条件下,以Fe（OH）3溶胶为前驱物,通过在有机溶剂中回流加热脱水,得到了分散性良好的α-Fe2O3纳米管。对产物进行表征,XRD结果证实产物为三角晶系的α-Fe2O3,且纯度较高;TEM分析表明产物为分散性良好的单晶。进一步研究了该纳米管的形成机理,为先形成薄片状结构,再进一步卷曲为管状形貌。     

灭火气溶胶发生剂灭火机理及配方设计

通过研究烟雾灭火剂与干粉灭火剂，探讨了灭火气溶胶发生剂的主要组分的选择原则,论述了灭火气溶胶发生剂的灭火机理,并由正交试验确定了发生剂的基本配方,试验证明灭火效果符合要求。     

无机、有机高分子絮凝剂絮凝机理及进展

论述了目前关于无机、有机高分子絮凝剂和复合絮凝剂的絮凝机理和研究进展,并展望了絮凝剂的研究趋势和发展方向.     

Interpretation of Secondary Organic Aerosol Formation from Diesel Exhaust Photooxidation in an Environmental Chamber

Secondary organic aerosol (SOA) formation from diesel exhaust was investigated using an environmental chamber. Particle volume measurement based solely on mobility diameter underestimated the SOA formation from diesel exhaust due to the external void space of agglomerate particles. Therefore, particle mass concentration and fractal-like dimension was determined from the particle effective density as a function of particle mass using an aerosol particle mass analyzer and scanning mobility particle sizer (APM–SMPS). Continuous aging of aerosol measured by an increase of atomic ratio (O/C) underscored the importance of multigenerational oxidation of low-volatile organic vapors emitted from diesel engine as a possible significant source of ambient oxygenated SOA. Higher particle effective densities were observed when raw exhaust was injected into a full bag as opposed to filling a bag with diluted exhaust using an ejector diluter. This suggests that the dilution method, in addition to dilution ratio, may impact the evaporation of semivolatile species. This study demonstrates the critical need to evaluate particle mass when evaluating SOA formation onto fractal particles such as diesel exhaust.     

Secondary Organic Aerosol Coating Formation and Evaporation: Chamber Studies Using Black Carbon Seed Aerosol and the Single-Particle Soot Photometer

We report a protocol for using black carbon (BC) aerosol as the seed for secondary organic aerosol (SOA) formation in an environmental chamber. We employ a single-particle soot photometer (SP2) to probe single-particle SOA coating growth dynamics and find that SOA growth on nonspherical BC aerosol is diffusion-limited. Aerosol composition measurements with an Aerodyne high resolution time-of-flight aerosol mass spectrometer (AMS) confirm that the presence of BC seed does not alter the composition of SOA as compared to self-nucleated SOA or condensed SOA on ammonium sulfate seed. We employ a 3-wavelength photoacoustic soot spectrometer (PASS-3) to measure optical properties of the systems studied, including fullerene soot as the surrogate BC seed, nucleated naphthalene SOA from high-NO_x photooxidation, and nucleated α-pinene SOA from low-NO_x photooxidation. A core-and-shell Mie scattering model of the light absorption enhancement is in good agreement with measured enhancements for both the low- and high-NO_x α-pinene photooxidation systems, reinforcing the assumption of a core-shell morphology for coated BC particles. A discrepancy between measured and modeled absorption enhancement factors in the naphthalene photooxidation system is attributed to the wavelength-dependence of refractive index of the naphthalene SOA. The coating of high-NO_x α-pinene SOA decreases after reaching a peak thickness during irradiation, reflecting a volatility change in the aerosol, as confirmed by the relative magnitudes of f₄₃ and f₄₄ in the AMS spectra. The protocol described here provides a framework by which future studies of SOA optical properties and single-particle growth dynamics may be explored in environmental chambers.

Copyright 2013 American Association for Aerosol Research     

宝浪油田地层结垢机理研究

对宝浪油田地层结垢倾向进行了理论分析,对宝浪油田地层结垢机理进行了静态试验研究.     

还原焰烧成分相花釉的研制与形成机理探讨

针对还原焰烧成陶瓷西餐具的需要,对还原焰分相花釉的釉料组成、工艺条件、外观效果、低倍结构作了实验研究,并进一步探讨了分相花釉的形成机理。     

Estimation of Formation Enthalpies of Organic Pollutants from a New Structural Group Contribution Method

Chemical stability and reactivity of organic pollutants is dependent to their formation enthalpies. The main objective of this study is to provide simple straightforward strategy for prediction of the formation enthalpies of wide range organic pollutants only from their structural functional groups. Using such an extended dataset comprising 1694 organic chemicals from 77 diverse material classes benefits the generalizability and reliability of the study. The new suggested collection of 12 functional groups and a simple linear regression lead to promising statistics of R²=0.958, Q_Loo²=0.956, and δ_AEE=57 kJ·mol^-1 for the whole dataset. Moreover, unknown experimental formation enthalpies for 27 organic pollutants are estimated by the presented approach. The resultant model needs no technical software/calculations, and thus can be easily applied by a non-specialist user.