Ozone Degradation of Polycyclic Aromatic Hydrocarbons Adsorbed on Asbestos

Abstract

The polycyclic aromatic hydrocarbons (PAH) represent a major source of pollution. The adsorption properties of chrysotile give us a good application as an asbestos filter and the regeneration can be made by ozonolysis for a complete destruction to non toxic compounds.     

Interaction of Aromatic Hydrocarbons with Sulfuric Acid,Bisulfate and Sulfate Anions

<正>Intermolecular geometries and energies of the dimers formed between simple aromatic hydrocarbons(benzene,toluene and naphthalene)and sulfate species(sulfuric acid, bisulfate and sulfate)were studied by density functional theory.The AH:H_2SO_4 complexes were determined by the OH-πH-bond,with H_2SO_4 acting as the H-bond donor and AHs as the acceptor. However,the AHs:HSO_4~-and AHs:SO_4~(2-)complexes were established by the H-bond,with AHs serving as acid and HSO_4~-or SO_4~(2-)as alkali.The atmospheric implications of those complexes were strongly supported by their considerable binding energies.     

Photochemical Degradation of Polycyclic Aromatic and Nitroaromatic Hydrocarbons in the Urban Atmosphere

Possible mechanisms of the photochemical conversion of polycyclic aromatic and nitroaromatic hydrocarbons in the urban atmosphere under the action of sunlight were analyzed. A kinetic model of the process was proposed, which takes into account the emission of harmful substances and the deposition of these substances onto the Earth's surface. It was found that emission is a predominant process within the bounds of a city. Beyond the precincts of a city, the concentrations of these hydrocarbons decrease because of photochemical degradation. In this case, the rate of this process for compounds adsorbed by soot particles is much higher than the corresponding value for compounds that occur in the gas phase. The results of calculations were compared with measurement data.     

Computational Studies on the Reactivity of Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are widely present in the environment as toxic pollutants. In this study, quantum chemistry methods are used to study reactions of PAHs in both particle and gas phases. Seven theoretical methods are exploited to predict the reactive sites of 15 PAHs in the particle phase. Among these methods, the performance of the condensed Fukui function (CFF) is optimum. The gas-phase reactions of eight PAHs are also investigated. Except for fluorene, CFF predicts correctly the gas-phase mono-nitro products for seven systems. The products of fluorene predicted by CFF are 1-nitrofluorene and 3-nitrofluorene, which is however inconsistent with the experimental results. Transition state theory is then used to investigate the reaction mechanism of fluorene. Calculated rate constants for 3-nitrofluorene and 2-nitrofluorene formation are much bigger than that for 1-nitrofluorene formation, which is in agreement with the experimental results.     

Microbial Degradation of Halogenated Hydrocarbons: A Biological Solution to Pollution Problems?

Chlorinated hydrocarbons are widely used because of their chemical and thermal stability as well as their fungicidal, herbicidal, and insecticidal properties. Unfortunately, it is just this stability that makes the compounds persistent in nature; half-lives of more than 15 years are not uncommon. In many countries the use of some chlorinated compounds has been prohibited, even though many such compounds (e.g., DDT) exhibit exactly the desired spectrum of effects. Surprisingly, microbiol systems that can degrade most chlorinated hydrocarbons have been found in nature. Indeed, it is possible, in many cases, to isolate pure cultures of bacteria that can utilize these compounds as the sole source of carbon and energy. Even polychlorinated compounds, such as the wood preservative and herbicide pentachlorophenol, can be utilized as a source of carbon by some bacteria. The study of the biodegradation of halogenated hydrocarbons has led to the discovery of novel catabolic pathways in which unusual and previously undescribed enzymatic activities have been detected. Bacterial enzymes have even been isolated that can replace halogen substituents in aliphatic and aromatic compounds with hydroxyl groups or hydrogen atoms. Improved understanding of the biodegradation of halogenated hydrocarbons, as described in this article, will almost certainly result in new biotechnological applications, especially in the area of waste-water treatment.     

用固体基质室温燐光法分析环境样品中多环芳烃的研究

用滤纸基质室温燐光法分析多环芳烃。以醋酸铊TlAc/醋酸铅Pb(Ac)_2(1∶1mol)的乙醇水(50％V/V)溶液为重原子微扰剂,对国产分析滤纸,玻璃纤维滤膜和醋酸纤维滤膜等9种不同的基质材料测定芘的燐光信号强度并进行了比较。对芘、荧蒽、苯并(e)芘、苯并(a)芘、苯并(ghi)芘和晕苯的混合物样品进行了测定。对煤飞灰和燃煤排放物样品中的芘和苯并(a)芘进行了定量分析,并用高效液相色谱法对测定结果进行验证。对芘和苯并(a)芘的检测限分别达到10~(-10)和10~(-9)g数量级。本文还对进一步提高灵敏度的问题进行了讨论。     

羟基多环芳烃的电喷雾电离离子阱串联质谱检测

采用电喷雾电离离子阱串联质谱检测了1-/2-羟基萘、 2-羟基芴、 2-/3-/4-/9-羟基菲、 6-羟基屈和3-羟基苯并[a]芘等9种不同环数的羟基多环芳烃(OH-PAHs, 2~5环), 考察了碰撞诱导解离操作参数活化值Q和相对碰撞能量对羟基多环芳烃各单体碎片离子产率的影响. 通过优化活化值Q和相对碰撞能量, 得到了3-羟基苯并[a]芘的碎片离子, 提高了1-羟基萘、 2-羟基芴、 3-/9-羟基菲和6-羟基屈碎片离子的产率, 并发现活化值Q是电喷雾电离离子阱串联质谱检测不同环数PAHs的关键参数.     

Weak-Link Versus Active Carbon Degradation Routes in the Oxidation of Aromatic Heterocyclic Systems. II

A series of benzimidazole and benzimide model compounds were oxidatively degraded at high temperatures (350-600°C). All of the compounds degraded to small fragments, i.e., carbon oxides, cyanogen (trace), and water, as well as condensable materials such as nitriles and anhydrides. The most outstanding feature of the degradation was the origin of these latter pyrolysis products; in each case they originated from the acid portion of the molecule. Nitrogen was noticeably absent in both the gas phase and the condensable degradation products except as nitrilo-moieties. Poly-2,2′(m-phenylene)53′-bibenzimidazole produced similar products. The proposed mechanism invokes a preferential attack by oxygen at the aminobenzenoid rings.     

Weak-Link Versus Active Carbon Degradation Routes in the Oxidation of Aromatic Heterocyclic Systems. IV

The oxidation of polybenzimidazolone and selected model compounds including compounds containing benzimidazole and benzimide ring systems has been investigated at temperatures from ambient to 700°C. Residue elemental analyses, volatile product distribution differences as a function of time and oxidation temperature, thermogravimetry, and differential thermal analysis studies are reported. The determination of the energy of activation for the over-all initial oxidation processes over the ranges of 0 to 15% weight loss and 100 to 700°C indicated a value of 35.5 kcal/mole. The elemental analyses data indicate that significant differences in residue composition exists between model compounds having aminederived end groups and those systems bearing acid-derived end groups. Data obtained using differential thermal analyses techniques indicate little difference in the thermal behavior of the benzimidazolones in inert or oxygen atmospheres. The changes in the amounts of carbon dioxide and carbon monoxide as a function of temperature and time support a proposal for simultaneous thermal and thermooxidation processes for the degradation of these systems in oxygen atmospheres at high temperatures.     

Weak-Link Versus Active Carbon Degradation Routes in the Oxidation of Aromatic Heterocyclic Systems. III

A polybenzimidazolone prepared by the condensation of 1,45,8-naphthalene tetracarboxylic acid and 3,3′-diaminobenzidine and several model compounds were thermally degraded (300-500°C) under inert and oxidative conditions. In every case only small fragments, i.e., carbon oxides, cyanogen (trace), and water, were detected by spectroscopic and chromatographic analysis of all phases of the pyrolysis products. The significance of these results is discussed in light of the mechanism by which this aromatic heterocyclic system undergoes oxidative degradation.     

Studies on the Interaction of Poly(I:C) with Heterocyclic Compounds Containing Iodine

The iodine heterocvclic compound with trivalent-iodine as the cation has a specially remarkable antitumor activityii^[1]. Although 3, 6-bis (dimethylamino)-dibenzopyriodonium formate([I⁺]) inhibits DNA biosynthesis of cancer cells in vitro, the way of [I⁺] depressing DNA synthesis has not been studied. It is significant to investigate the mechanism of the interaction of [I⁺] with nucleic acids.     

Separation of Mycotoxins,Polycyclic Aromatic Hydrocarbons,Quinones, and Heterocyclic Compounds on Cyclodextrin Bonded Phases: An Alternative LC Packing

Abstract

β-Cyclodextrin and γ-cyclodextrin chiral bonded phases were previously shown to be useful in the separation of enantiomers, diastereomers and structural isomers. In this work it is demonstrated that these stationary phases are also useful in more routine separations. As such, they provide an alternative to the popular reverse phase packings. Because the selectivity of cyclodextrin packings is often unique they can be used to compliment conventional columns, particularly when separating complex mixtures where peak overlap is a problem. The separation of several important classes of compounds is used to demonstrate the general utility of this packing.     

硼氮杂稠环化合物的合成与电子学应用

有机半导体材料的开发为有机电子学的发展提供了材料基础。杂原子的引入进一步丰富了材料的种类和数量。作为CC单元的等电子体,BN单元对有机半导体材料的性能调节受到了科学家们的关注。本文主要介绍了有机共轭体系中BN单键的构筑方法,以及这类硼氮杂稠环分子在有机电子学领域的应用。     

多环芳烃的污染及防治

多环芳烃污染是有机污染中最常见的一种,也是对人体危害较大的一种。本文较为详细地阐述了多环芳烃污染的来源、对人体的危害及防治措施。     

Six-Membered Aromatic Nitrogen Heterocyclic Anti-Tumor Agents: Synthesis and Applications

Cancer stands as a serious malady, posing substantial risks to human well-being and survival. This underscores the paramount necessity to explore and investigate novel antitumor medications. Nitrogen-containing compounds, especially those derived from natural sources, form a highly significant category of antitumor agents. Among these, antitumor agents with six-membered aromatic nitrogen heterocycles have consistently attracted the attention of chemists and pharmacologists. Accordingly, we present a comprehensive summary of synthetic strategies and clinical implications of these compounds in this review. This entails an in-depth analysis of synthesis pathways for pyridine, quinoline, pyrimidine, and quinazoline. Additionally, we explore the historical progression, targets, mechanisms of action, and clinical effectiveness of small molecule inhibitors possessing these structural features.     

Synthesis of Bacterial Metabolites of Polycyclic Aromatic Hydrocarbons: Benzochromenones,o‐Carboxyvinylnaphthoates,and o‐Substituted Aryl‐α‐Oxobutenoates

Bacterial metabolites of phenanthrene and anthracene include benzochromenones, o‐carboxyvinylnaphthoates, and o‐substituted aryl α‐oxobutenoates, which were synthesized with the Wittig reaction, the Heck reaction, and coupling of aromatic aldehyde with pyruvate.     

羟基取代的多环芳烃与一氧化氮的反应研究

内源性的一氧化氮(NO)是多种生理过程中必不可少的信使分子,它在神经系统递质传导、神经发育、脑血流调节以及免疫调节等过程中具有十分重要的作用。为揭示NO生理功能的化学本质,NO成为化学家近年来研究的重要课题之一。     

Extraction of Aromatic Hydrocarbons with Triethylene Glycol-Sulfolane Mixed Extractant

Comparative analysis is made of the operation of an extraction block of the LG 35-8/300B benzene reforming unit (Kirishinefteorgsintez Production Association) before and after its upgrade (with triethylene glycol-sulfolane-water mixed extractant used instead of straight triethylene glycol).     

多环芳烃在盐溶液中盐析常数和活度系数的研究

研究盐类对多环芳烃溶解度的影响,不仅涉及盐效应各种理论的研究,而且在化工分离、环境治理上也有重要的实际意义。本文研究了25℃下7种多环芳烃在NaCl水溶液中的活度系数和盐析常数。计算并比较了萘和联苯的盐析常数以及5种多环芳烃在被正辛醇饱和的NaCl水溶液中的活度系数和盐析常数。