水环境介质中有机污染物微观分布的理论模型——污染物·水复合体·水簇模型

以水簇模拟水环境介质, 水体中有机污染物的分子状态用水-有机污染物分子复合体模拟,得出有机污染物在水环境介质中微观分布的数学表达式, 经过微观动力学方法处理, 得到了相应的数学解析式.用 ab initio 方法 STO-3G 基组计算了4个多环芳烃在水中的微观分布情况, 计算结果与辛醇-水分配系数的实验值相吻合.     

有机污染物在水环境介质中分布的理论研究

用物理化学原理从分子水平研究有机污染物在水环境介质中的分布。建立了模拟水环境介质一维模型，推导出计算分布值的数学表达式．     

水中有机污染物微观分布的理论模型与方法

考虑实际水体,建立了有机污染物在水中分布的理论模型,用物理化学方法推导出计算污染物在水体中分布的数学方程式和数学解析式.用MNDO方法计算了卤代苯的相对分布值(PN),结果与辛醇-水分配系数实验值相符合.     

废水中有机污染物降解机理的研究方法

我国废水排放总量较大,且废水中含有的多种有机污染物一直是人类生命健康的潜在威胁,因此对废水处理的研究必不可少,而理解废水中有机污染物的降解机理是处理各种废水的基础.本综述概述了国内外针对各种有机污染物降解机理的研究方法,主要包括实验手段和计算模拟两大类.实验手段中主要采用光谱分析技术检测有机污染物降解过程中生成的中间产物,进而推测有机污染物的降解路径.但是由于实验条件和实验方法的不同,对于同种物质的降解机理研究,不同的实验结果存在着争议.基于量子化学计算、定量构效关系模型（QSAR）、定量结构-生物降解性能关系模型（QSBR）、统计分子碎化模型（SMF）等计算模拟方法为有机污染物降解机理的研究提供了新的方法.将实验手段和计算模拟有机结合起来,可为有机污染物的降解机理研究提供参考和指导.     

卤代甲烷在一维四聚体水簇上分布的理论研究

运用量子化学方法讨论了一维四聚水簇的各种不同构成形式的稳定性,并计算了有机污染物卤代甲烷在一维四聚体水簇不同位置上的相对分布值,计算结果表明,有机污染物在水体边界的相对分布值高于水体介质内部的相对分布值。     

太湖水体中有机污染物的分析

利用超临界流体萃取与热脱附两种样品预自理方法的优势互补,与气相色谱分析相结合对太湖水体中不同沸点有机污染物进行了分析,发现太湖水中除了烃类污染物外还存在大量含氮有机污染物。其分布表明入湖河道中排放的工业污染物的流入是导致太湖水富营养化的一个重要因素。     

珠江三角洲典型有机污染物的环境行为及人群暴露风险

珠江三角洲是我国经济最为发达的地区之一,也是环境污染问题最为严峻的地区之一。严峻的环境污染问题毫无疑问地将影响地区经济的可持续发展与人体健康。大量的研究表明,多种传统和新型的有机污染物在珠江三角洲各类环境介质、生物体、甚至人体中广泛存在。这些污染物包括多溴联苯醚(PBDEs)、多氯联苯(PCBs)、有机氯农药(OCPs)、有机磷酸酯类阻燃剂(OPEs)等。系统研究污染物的环境行为及人体暴露风险具有重要的科学和现实意义,可以为政策制定者采取有效的污染物控制措施提供科学数据支持。有机污染物在环境界面(沉积物-水、大气-水及土壤-水)迁移是控制其地球化学行为的重要过程。本文综述了珠江三角洲典型有机污染物的宏观环境行为、微观的环境界面通量测定技术、人体暴露风险三个方面的研究历史及现状,并总结了现有研究的不足,展望了研究趋势。     

土壤胶体迁移行为及其介导污染物迁移模拟与研究进展

本文综述了土壤多孔介质中胶体迁移的释放与沉积机制、影响胶体迁移的多种因素以及土壤中胶体与各种污染物的协同迁移作用,总结了模拟胶体迁移的数学模型以及计算机软件的应用。研究表明,胶体在土壤中的迁移主要受应变、附着、薄膜应变等迁移机制的影响,多孔介质的性质、流体的性质以及胶体自身的性质也会影响胶体的迁移。此外,胶体能有效吸附地下水多孔介质中的有机或无机污染物,并对其在地下环境中的迁移产生显著影响。目前已有许多学者通过数学模型来模拟胶体在土壤中的迁移过程,而计算机技术的进步也将促进更加先进的软件模型应用到胶体迁移的模拟中。     

微塑料环境赋存及其与有机污染物的作用机理研究进展

微塑料(MPs)普遍存在于全球各种环境介质中,可以吸附共存的污染物,尤其是有机污染物,进而改变其环境行为和毒性,也可以通过吸附/解吸作用促进污染物在不同介质中的迁移. MPs与有机污染物的吸附影响因素及其作用机理是准确评估MPs和有机污染物环境风险的必要信息.因MPs成分、结构、表面特征等的复杂性及其共存有机污染物的多样性使两者的相互作用十分复杂.本文对MPs在环境介质中的赋存、迁移、吸附有机污染物的影响因素及其相互作用机理进行了系统总结,以期为进一步评估MPs的环境行为和生态风险提供参考.     

环境中有机磷污染物碱性的理论研究

有机膦化合物的碱度对深入了解有机膦类污染物的降解有着重要的意义. 发展基于第一性原理的理论方法精确计算有机膦化合物的pKa值有重要意义. 本研究工作发展了精确计算有机膦阳离子化合物pKa值的方法: 用B3LYP/6- 31＋G(d)优化气相结构, PBEPBE计算单点能量, IEFPCM/Bondi (f＝1.0)计算溶剂化能. 理论值与实验值比较, 其平均偏差和均方根差分别为－0.6 pKa单位和0.7 pKa单位. 基于此方法, 我们研究了常见有机膦污染物阳离子的碱性, 定量计算其pKa值. 并进一步讨论了这类化合物的α取代效应和远程取代效应对其碱性的影响, 总结了影响杂环有机膦化合物阳离子酸性的因素.     

Molecular dynamics simulation of the water|nitrobenzene interface

The structure and dynamics of the neat water|nitrobenzene liquid|liquid interface are studied at 300 K using molecular dynamics computer simulations. The water is modeled using the flexible SPC potential, and the nitrobenzene is modeled using an empirically determined nitrobenzene potential energy function. Although nitrobenzene is a polar liquid with a large dielectric constant, the structure of the interface is similar to other water|non-polar organic liquid interfaces. Among the main structural features we describe are an enhancement of interfacial water hydrogen bonds, the specific orientation of water dipoles and nitrobenzene molecules, and a rough surface that is locally sharp. Surface roughness is also characterized dynamically. The dynamics of molecular reorientation are shown to be only mildly modified at the interface. The effect due to the polarizable many-body potential energy functions of both liquids is investigated and is found to affect only mildly the above results.     

Removal of organic pollutants from water via molecular inclusion within a cavitand

The molecular inclusion chemistry of cavitands provides a useful way for the removal of organic pollutants from water. A wide range of lipophilic organic compounds, present at trace level in water, are efficiently extracted by cavitand1, which can be easily reactivated and reused.     

Deliquescence and efflorescence behavior of ternary inorganic/organic/water aerosol particles

The deliquescence behavior of ternary inorganic (ammonium sulfate and ammonium nitrate)/organic (glutaric acid and malonic acid)/water aerosol particles has been investigated at 293 K using a novel surface aerosol microscopy (SAM) technique. The results obtained for the deliquescence relative humidities (DRH) for particles of variable inorganic/organic contents show a eutectic behavior with the mixed particles showing deliquescence at lower DRH compared to the pure inorganic and organic components, respectively. This behavior has been quantitatively modeled using the extended aerosol inorganics (E-AIM) thermodynamic model of Clegg et al. in combination with the UNIFAC group activity approach to account for organic molecular solutes. In addition, we have investigated the crystallization behavior of supersatured and formerly deliquesced ternary solution droplets using space resolved Raman spectroscopy. It is found that such droplets produce solid particles in which the inorganic and organic phases show some spatial separation with the organic component being predominantly found at the outer part of the particle. Independent measurements of the contact angles of such ternary droplets reveal that their angles are within experimental error identical to those of the purely organic/water solutions.     

Investigating sorption-driven dissolved organic matter fractionation by multidimensional fluorescence spectroscopy and PARAFAC

Soil organic matter is involved in many ecosystem processes, such as nutrient supply, metal solubilization, and carbon sequestration. This study examined the ability of multidimensional fluorescence spectroscopy and parallel factor analysis (PARAFAC) to provide detailed chemical information on the preferential sorption of higher-molecular-weight components of natural organic matter onto mineral surfaces. Dissolved organic matter (DOM) from soil organic horizons and tree leaf tissues was obtained using water extracts. The suite of fluorescence spectra was modeled with PARAFAC and it was revealed that the DOM extracts contained five fluorescing components: tryptophan-like (peak location at excitation <255 nm:emission 342 nm), tyrosine-like (276 nm:312 nm), and three humic-substance-like components (<255 nm:456 nm, 309 nm:426 nm, <255 nm:401 nm). In general, adsorption onto goethite and gibbsite increased with increasing DOM molecular weight and humification. PARAFAC analysis of the pre- and post-sorption DOM indicated that the ordering of sorption extent was humic-like components (average 91% sorption) > tryptophan-like components (52% sorption) > tyrosine-like components (29% sorption). This differential sorption of the modeled DOM components in both the soil organic horizon and leaf tissue extracts led to the fractionation of DOM. The results of this study demonstrate that multidimensional fluorescence spectroscopy combined with PARAFAC can quantitatively describe the chemical fractionation process due to the interaction of DOM with mineral surfaces.     

有机半导体非平衡态HOMO和LUMO能量位移规律与OLED中“热激子”形成的唯象理解

以能斯特方程为基础, 通过分析电流密度与氧化还原物种活度变化, 即载流子浓度变化的关系, 计算出有机半导体材料电极电势的变化, 从而建立起有机半导体前线轨道, 即最高占据分子轨道(HOMO)能级和最低未被占据分子轨道(LUMO)能级相对于热力学平衡态的能量位移随电流密度变化的数学关系. 进而依据能级能量位移引起的能隙变化, 提出了有机电致发光显示器（OLED）中“热激子”的产生机制.     

Supercritical fluid extraction coupled with chromatography-mass spectrometry: Hair analysis. Chromatography-mass spectrometry data processing using the CODA mathematical algorithm

The composition of medium-volatility organic compounds extracted from human hair using supercritical fluid extraction (SFE) was determined. The entire extract was trapped from a gas flow in a sorption device at the extractor outlet and thermally desorbed into a gas chromatography-mass spectrometry (GC-MS) instrument. The extracted compounds were identified either by the direct processing of GC-MS data or using the CODA mathematical algorithm. The combination of solventless SFE with the transfer of the entire extract into a GC-MS instrument with the direct analysis of GC-MS data allowed us to determine organic compounds at a level of 3.9 pg/mg hair. The CODA mathematical algorithm for the processing of GC-MS data allowed us to determine compounds at a level of 1.7 pg/mg hair; in the majority of publications, this determination limit was achieved either by selective ion detection or using a GC-MS-MS technique.     

Chemistry between magnesium and multiple molecules in tris(8-hydroxyquinoline) aluminum films

Metal organic contacts are at the basis of devices such as organic light emitting diodes (OLEDs). Here, we report a theoretical investigation of the chemical interaction between a Mg atom and an organic film made of tris(8-hydroxyquinoline)aluminum (Alq3) molecules. The latter is modeled either by an isolated molecule or by a bulk crystal. Using first-principles molecular dynamics for structural optimization, we find that an isolated Alq3 molecule and a Mg atom form an ion-pair. However, when the metal atom interacts with molecules in a bulk crystalline environment, we find that an organometallic complex is energetically preferred over the ion-pair. The complex formation is an effect of the environment which makes possible the interaction of the metal atom with several adjacent molecules. Here, our calculated O(1s) and N(1s) core level shifts agree well with recent experimental data on Alq3 films exposed to Mg. Our results resolve the apparent contradiction between experiment and predictions made in previous calculations in which a single Alq3 molecule was used to model a thin film.