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The Use of Denuders for Semivolatile Characterization Studies in Outdoor Chambers
Published in Douglas A. Lane, Gas and Particle Phase Measurements of Atmospheric Organic Compounds, 2020
Richard Kamens, Zhihua Fan, Myosoen Jang, Jay Odum, Jianxin Hu, Dana Coe, Jianbo Zhang, Shufen Chen, Keri Leach
To demonstrate the feasibility of this technique, fresh diesel emissions were added through a 10m × 7 cm pipe to the inlet of the stripper (26°C). By the time the emissions reached the inlet of the large stripper they were diluted by approximately a factor of two with ambient air. The flow was such that the residence time in the zones of the carbon filter paper was about 6–10 seconds. A comparison of the inlet and outlet gas phase PAH concentrations (Figure 7) revealed that most volatile compounds (naphthalene, acenaphthylene and fluorene) were effectively removed by the stripper walls. As volatility decreased, however, the relative amount of gas phase PAH observed at the outlet compared to the inlet increased. Comparisons of particle phase PAH (normalized for particle mass) at the inlet and outlet of the large stripper-denuder showed that almost all of the most volatile PAH (see ace-naphthylene Ace, fluorene Fl and phenanthrene Phe in Figure 8) were lost from the particles as the particles passed through the gas stripper. Less volatile pyrene and fluoranthene still exhibited a 30–50% particle loss, while BaA and chrysene—triphenylene showed no loss.
Fullerenes and Polycyclic Aromatic Hydrocarbons in Separation Science
Published in Paweł K. Zarzycki, Pure and Functionalized Carbon Based Nanomaterials, 2020
Yoshihiro Saito, Koki Nakagami, Ohjiro Sumiya, Ikuo Ueta
PAHs is a group of aromatic compounds having a unique molecular shape and size, as illustrated in Figure 12.1, and there are many homologues as typically recognized as naphthalene (C10H8), anthracene (C14H10), and naphthacene (C18H12), with increasing the number of aromatic rings. At the same time, all the PAHs consisting of more than three aromatic rings have corresponding isomer(s). For example, the PAH with the molecular formula of C18H12 consisted of five isomers, triphenylene, benzo[c] phenanthrene, benz[a]anthracene, chrysene, and naphthacene. An increased number of isomers can be expected with increasing the number of aromatic rings in PAHs. However, it suggests that the difference in the entire molecular structure of isomers will be relatively smaller when increasing the number of aromatic rings. To systematically describe the molecular structure of PAHs, especially in the analysis of retention behavior, several size and shape parameters have been proposed.
Field-Scale Remediation of Crude Oil–Contaminated Desert Soil Using Various Treatment Technologies
Published in Ram Chandra, R.C. Sobti, Microbes for Sustainable Development and Bioremediation, 2019
Subhasis Das, Veeranna A. Channashettar, Nanthakumar Kuppanan, Banwari Lal
Crude oil is a complex mixture of an indefinite number of individual chemical compounds, and the properties of these compounds differ depending on many factors, such as source, geological history, age, migration, and alteration of crude oil. The PHCs in crude oil contain a complex mixture of four fractions: saturates, aromatics, resins (N, S, O), and asphaltene (Balba et al., 1998). The saturate fractions are straight chain alkanes (all normal alkanes), branched alkanes (isoalkanes), and cycloalkanes (naphthenes). The aromatic fractions contain volatile monoaromatic hydrocarbon (benzene, toluene, xylene etc.), polyaromatic hydrocarbon (PAH) (three-ring compounds—anthracene, phenanthrene; four-ring compounds—tetracene, chrysene, triphenylene; five-ring compounds—pentacene, benzopyrene, corannulene, benzopyrene; six-ring compound—coronene; and seven-ring compounds—ovalene and benzofluorene), naphthenoaromatics, and aromatic sulfur compounds (Figure 7.1). The resin and asphaltene fractions consist of polar molecules containing nitrogen, sulfur, and oxygen. Resins are amorphous in nature and dissolved in oil, whereas asphaltenes are of a big colloidal shape and dispersed in oil. It is notable that PAH fractions associated with oil contamination, as well as known carcinogens, are suspected. The most toxic PAH compound is benzopyrene.
An overview of organic geochemical indices to evaluate conventional petroleum source rocks: a summary of examples from the Indian Subcontinent
Published in Petroleum Science and Technology, 2022
Polycyclic aromatic hydrocarbons (PAHs) have been investigated in a variety of geological settings (especially in coal beds) to understand maturity, source composition, and paleoclimate based on combustion-derived and land-plant-derived OM. However, such organic geochemical studies are rare in the Indian Subcontinent for understanding source rock characteristics of shale, lignite and coal beds, and reconstructing paleoclimate (e.g., Dutta et al. 2011; Misra et al. 2019; Hossain et al. 2020). Figure 5c indicates different PAHs such as (abundant) retene, simonellite, perylene, (minor) cadalene, phenanthrene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzofluoranthene, benzo[e]pyrene, benzo[a]pyrene, indeno[cd]pyrene, benzo[ghi]perylene in coaly shale of the Andigama Basin. The origin of these OMs can be recognized as markers for (i) vascular plants from gymnosperm (retene, simonellite, perylene, and phenanthrene derivatives), (ii) high-temperature crown fire (benzo[e]pyrene, indeno[cd]pyrene, and benzo[ghi]perylene), and (iii) medium temperature ground fire (pyrene, benzo[a]anthracene, chrysene/triphenylene and benzofluoranthene) (e.g., Ratnayake and Sampei 2015; Hossain et al. 2020).
A review on biotransformation of polyaromatic hydrocarbons mediated by biosurfactant producing bacteria
Published in Petroleum Science and Technology, 2022
Soni Kumari Singh, Ashish Sachan
Polyaromatic hydrocarbons are uncharged, lipophilic and non polar molecules composed of hydrogen and carbon. PAHs consist of multiple aromatic rings, produced by thermal de - composition of organic compounds. Principal PAHs compounds are anthracene, phenanthrene, phenalene, tetracene, chrysene, triphenylene, pyrene, pentacene, benzo[a]pyrene, corannulene, benzo[ghi]perylene, coronene, ovalene and benzo[c]fluorine (Table 1). Sources of PAHs based on their origin are pyrogenic (incomplete combustion at high temperature), petrogenic (transportation and handling of crude oil products) and biogenic (decomposition of organic material) (Abdel-Shafy and Mansour. 2016; Mojiri et al. 2019). Polyaromatic hydrocarbons are considered as ubiquitous in our environment produced from natural or anthropogenic combustion processes (Abdel et al. 2016). Natural sources of PAHs are Biological decomposition, forest fires, deposition of sediments under oceans and other natural processes. Anthropogenic sources include activities related to petroleum products as refining, shipping, transportation and various automobiles industries.
First fluorescein liquid crystals: synthesis, mesomorphic and fluorescence properties of fluorescein-triphenylene dimers
Published in Liquid Crystals, 2020
Tianwen Fan, Rongxin Shi, Huaying Tang, Hongyu Guo, Fafu Yang
On the other hand, it was well known that fluorescein is one of the important dyes with high fluorescence [24]. Based on its characteristics of multipoint modification, all kinds of fluorescein derivatives were prepared and exhibited the diverse applications, such as biomarkers, probes for ions and biomolecules, and cell bio-imaging [25–32]. However, although the synthesis and properties of various fluorescein derivatives were reported, no fluorescein liquid crystal was presented so far. In this paper, we wish to report the first fluorescein liquid crystal based on fluorescein-triphenylene dimers. Moreover, the influence of peripheral alkyl chains on mesomorphic and fluorescence properties was studied in details. Some fluorescein-triphenylene dimers exhibited excellent columnar mesophase and good fluorescence in both solution and solid states.