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Biodegradation of Polynuclear Aromatic Hydrocarbons in Coal Tar Oil Contaminated Soil
Published in Donald L. Wise, Debra J. Trantolo, Remediation of Hazardous Waste Contaminated Soils, 2018
Curtis A. Lajoie, Peter F. Strom
To determine the effect of coal tar oil concentration on the rate of degradation, soils were amended with 0.5, 1.0, 2.5, 5.0, and 10 percent coal tar oil. Nitrogen and phosphorus fertilizer were added in proportion to the applied coal tar oil. The disappearance of phenanthrene during 12 weeks of incubation in each soil is indicated in Figure 2. Phenanthrene is a commonly used model substrate in studies of PAH degradation,3 and due to its low vapor pressure, losses due to volatilization are expected to be negligible. If assessment of degradative activity is based on the disappearance of phenanthrene, a concentration range up to 2.5 percent coal tar oil still allowed for effective decontamination over a 12-week period. After 12 weeks the total of 16 coal tar oil constituents (in the molecular weight range of indene to benzo(a)pyrene) in the soil contaminated initially with 2.5 percent coal tar oil decreased from 17,200 to 3500 ppm. In the soil contaminated initially with 1.0 percent coal tar oil, PAH concentration decreased from 5450 to 300 ppm during the same period. These are reductions in the total coal tar oil constituent concentrations of 80 and 95 percent in soils contaminated with 2.5 and 1.0 percent coal tar oil, respectively.
List of Chemical Substances
Published in T.S.S. Dikshith, and Safety, 2016
2,3-Benzofuran is a colorless, sweet-smelling, oily liquid made by processing coal into coal oil. It may also be formed during other uses of coal or oil. 2,3-Benzofuran is not used for any commercial purposes, but the part of the coal oil that contains 2,3-benzofuran is made into a plastic called coumarone-indene resin. This resin resists corrosion and is used to make paints and varnishes. The resin also provides water resistance and is used in coatings on paper products and fabrics. It is used as an adhesive in food containers and some asphalt floor tiles. The resin has been approved for use in food packages and as a coating on citrus fruits. We do not know how often the resin is used or whether any 2,3-benzofu-ran in the coating or packaging gets into the food. 2,3-Benzofuran may enter the air, water, and soil during its manufacture, use, or storage at hazardous waste sites. Breathing contaminated air or touching the chemical in the workplace is the source of human exposure.
Rubber-Based Pressure-Sensitive Adhesives
Published in István Benedek, Mikhail M. Feldstein, Technology of Pressure-Sensitive Adhesives and Products, 2008
The first commercial coumarone–indene resin was manufactured in 1910. The basic material for the production of coumarone–indene resins is high-temperature coal tar. Coal tar is one of the by-products of coal carbonization. In the coking process, hard coal undergoes a pyrolytic conversion at temperatures of 1000–2000°C. The main product is coke but there are several by-products that are partly recoverable by condensation and extraction from the gases liberated during carbonization. Crude tar fraction accounts 3 wt % of the coal carbonization process. Distillation of coal tar renders less than 3 wt % coal-tar light oil, which is the main source for the manufacturing of coumarone–indene resins. This light oil fraction boils at 70–200°C and contains 10–40% unsaturated aromatics (Figure 2.8).
Polyaromatic hydrocarbons with an imperfect aromatic system as catalysts of interstellar H2 formation
Published in Molecular Physics, 2023
Dávid P. Jelenfi, Anita Schneiker, Attila Tajti, Gábor Magyarfalvi, György Tarczay
Indene and 1H-phenalene were investigated from among polycyclic species. Indene contains a six- and a five-membered ring and the sp C atom is part of the 5-membered ring. The barrier heights of the first H-atom-addition reactions of indene are both lower than that of benzene. On C2, a barrier of 6 and 10 kJ mol is seen, without and with ZPVE correction, respectively, whereas 14 and 18 kJ mol are found for the corresponding values in the C3 position (Figure 6). Similarly to cyclopentadiene, we can rationalise the energy difference of the two paths by the more extensive delocalisation in the radical formed in the C2 addition. Nevertheless, both H-atom-addition reactions of indene have considerably lower barriers than that of benzene.
Progress on rubber-based pressure-sensitive adhesives
Published in The Journal of Adhesion, 2018
Compared with block synthetic rubber-based PSAs, the tackifier resin in non-block synthetic rubber-based PSAs has a completely different effect on compatiblity; furthermore, there is large difference between tackifier types. In brominated isobutylene-co-p-methylstyrene (BIMS) rubber-based PSAs, Kumar et al. [66] found that the hydrocarbon resin that acted like dilute could effectively reduced the rubber plateau modulus of blend, so the blend had good tack. The formaldehyde resin is partly compatible with BIMS and seperated with BIMS even at low loading. The phenol formaldehyde resin in blend acks like filler and increases the rubber plateau modulus of blend, which results in the blend losing tack. For EPDM-based PSA, the hydrocarbon resin acts as a platicizer at lower frequency due to the reduction in the storage modulus of PSA, and as a filler at higher frequency due to increase in the storage modulus of PSA. The coumarone-indene resin does not show the same behavior as hydrocarbon resin [67]. The EPDM/hydrocarbon resin PSA has higher tack strength than the EPDM/coumarone-diene resin PSA. The compatibility of EPDM with tackifier resin dominates the PSA performance.
New negative dielectric anisotropy liquid crystals based on benzofuran core
Published in Liquid Crystals, 2020
Lingchao Mo, Jian Li, Zhaoyi Che, Yilin Cao, Zhongwei An, Xiaozhe Yang
Liquid crystals have been successfully used in various display devices. The most popular liquid crystal compounds used in display are composed of benzene and cyclohexane ring, and its structure-performance relationship has been revealed [1–3]. In the process of exploring new liquid crystals, compounds based on fused ring and fused heterocycle have become the focus of attention because of their variable structures and excellent performances [4]. 2,6-Substituted naphthalene ring is a kind of fused ring structure which has been used earlier for the design of liquid crystals [5–7]. Although it is beneficial to broaden the mesophase range and increase the birefringence, it has the disadvantages of high melting point and poor solubility. Indene and indane rings have good rigidity and linearity, and they were used to construct high performance liquid crystals [8], especially negative dielectric anisotropic liquid crystals [9]. In recent years, a lot of liquid crystal compounds containing fused heterocycles have been synthesised, including benzofuran [10,11], benzothiophene [12], benzoxazole [13–18], benzothiazole [19–21], benzimidazole [22,23], thieno[3,2-b]thiophene [24,25], dibenzothiophene [26] and so on. Polar heteroatom plays an active role in the regulation of the properties of liquid crystal molecules, and some of these new compounds show good application potential in devices beyond display [27,28]. These new fused heterocycles-based compounds have expanded our knowledge of liquid crystal’s structures and properties. Therefore, it is of great significance to explore new liquid crystal structures based on fused heterocycles.