Mixture Of Coal Tar Research Articles

SAR Models for Estimating the Percutaneous Absorption of Polynuclear Aromatic Hydrocarbons

A structure-activity relationship (SAR) of the in vitro percutaneous absorption of polycyclic aromatic hydrocarbons (PAH) is described. The data set consisted of 60 three to seven ring PAH. Over 50 numeric descriptors were generated from the modeled molecular structures. Computer aided methods were used to evaluate descriptors and develop linear expressions relating the percent of dermally applied PAH dose absorbed through skin (PADA) to PAH structure. Three regression models with one and two variables were developed. The log octanol/water partition coefficient (log P) was the most important variable in determining percutaneous absorption. An inverse relationship between log P and the skin penetration properties of the PAH was observed. Nearly 40 of 60 PAH tested had PADA-values within a factor of two of benzo[a]pyrene (BaP); well over 50 of 60 had PADA-values within a factor of three. The results lend support to the use of isotopically labeled BaP as a surrogate for measuring the dermal flux (in vivo and in vitro) and estimating the dermal bioavailability of PAH from complex mineral oil and coal-tar derived mixtures.

A comparison of the tumors induced by coal tar and benzo[a]pyrene in a 2-year bioassay

The tumorigenicity of two coal tar mixtures was compared to that of benzo[a]pyrene after 2 years of feeding. Mixture 1, a composite of coal tar from seven coal gasification plant waste sites, was fed to female B6C3F1 mice (48 mice per group) for 2 years at doses of 0.0, 0.01, 0.03, 0.1, 0.3, 0.6 and 1.0%. Mixture 2, which was composed of coal tar from two of the seven waste sites and another site having a high benzo[a]pyrene content, was fed at doses of 0.0, 0.03, 0.1 and 0.3%. Additional groups of mice were fed 0, 5, 25 and 100 ppm benzo[a]pyrene. The coal tar diets induced a dose-related increase in hepatocellular adenomas and carcinomas, alveolar/bronchiolar adenomas and carcinomas, forestomach squamous epithelial papillomas and carcinomas, small intestine adenocarcinomas, histiocytic sarcomas, hemangiosarcomas in multiple organs and sarcomas. Benzo[a]pyrene treatment resulted in an increased incidence of papillomas and/or carcinomas of the forestomach, esophagus and tongue. A comparison of the results indicated that the benzo[a]pyrene in the coal tar diets could be responsible for the forestomach tumors. In contrast, the lung and liver tumors appeared to be due to other genotoxic components contained within the coal tar mixture, while the small intestine tumors resulted from chemically-induced cell proliferation that occurred at high doses of coal tar.

97/05069 Correlation of mutagenic potencies of various petroleum oils and oil coal tar mixtures with DNA adduct levels in vitro: Reddy, M. et al. Mutat. Res., 1997, 378, (1,2), 89–95

97/05069 Correlation of mutagenic potencies of various petroleum oils and oil coal tar mixtures with DNA adduct levels in vitro: Reddy, M. et al. Mutat. Res., 1997, 378, (1,2), 89–95

Correlation of mutagenic potencies of various petroleum oils and oil coal tar mixtures with DNA adduct levels in vitro

An in vitro system was utilized to measure DNA adduct-forming ability of petroleum oils and oil coal tar mixtures to define correlations between DNA adduct levels and their mutagenic potencies. The system consisted of reaction of dimethyl sulfoxide extracts of oils with calf thymus DNA in the presence of Aroclor-induced hamster liver microsomes for 30 min. Following DNA extraction, DNA adducts were measured by the nuclease P1-enhanced postlabeling assay coupled with two-dimensional polyethyleneimine (PEI)-cellulose TLC. Thin layer plates showed putative aromatic DNA adducts, with levels ranging from 60 to 1400 adducts per 10 9 DNA nucleotides. TLC mobilities suggested adducts to be aromatic compounds containing 4 or more rings. A good correlation (coefficient of correlation=0.91) was observed between DNA adduct levels and Salmonella mutagenicity for 19 oils. All 19 samples tested produced DNA adducts. To expedite the TLC procedure, adducts were resolved by one-dimensional TLC and the radioactivity measured using a mechanical scanner. Results were comparable to those obtained by two-dimensional TLC and quantification after scraping. Our data show that the in vitro incubation system coupled with the postlabeling adduct assay is a useful screening method to identify mutagenic and potentially carcinogenic oils.

Chemical recycling of mixed plastics of pyrolysis

AbstractMost plastics are produced from oil and have a high potential as hydrocarbon sources for the chemical industry. Pyrolysis is a practicable way to pyrolyze mixed plastics. The fluidized bed pyrolysis has turned out to be particularly advantageous. Twenty‐five to 45% of product gas with a high heating value and 30–50% of an oil rich in aromatics could be recovered. The oil is comparable to that of a mixture of light benzene and bituminous coal tar. Up to 60% of ethene and propene are produced by using mixed polyolefins as feedstock. Under appropriate conditions the pyrolysis could be successful on the market. © 1995 John Wiley & Sons, Inc.

Pyrolysis with respect to recycling of polymer

AbstractMost plastics are produced from oil and have a high potential as hydrocarbon sources for the chemical industry. Pyrolysis is a practicable way to pyrolyze mixed plastics. The fluidized bed pyrolysis has turned out to be particularly advantageous. 25 to 45 percent of product gas with a high heating value and 30 to 50 percent of an oil rich in aromatics, could be recovered. The oil is comparable to that of a mixture of light benzene and bituminous coal tar. Up to 60 percent of ethene and propene are produced by using mixed polyolefins as feedstock. Under appropriate conditions the pyrolysis could be successful on the market.

Recycling of polymers by pyrolysis

The pyrolysis of plastic waste, scrap tires and other polymeric materials in a fluidized bed has been carried out based on a scale up program (laboratory plants 70 g/h, 500 g/h, 3000 g/h, and pilot plant 20-50 kg/h). The fluidized bed shows short residence times and high heat and mass transfers, and is heated indirectly up to 600-800°C. In the case of poly(methylmethacrylate) (PMMA) or polystyrene as feedstock up to 97 wt.% of the monomer can be recovered. Other polymers give a more unspecific product spectrum. Depending on the process parameters between 30 and 60% of the polymeric material could be recovered as oil which is comparable to that of a mixture of light benzene and bitumious coal tar if the pyrolysis gas is used as fluidizing gas. The other fractions are gas and a residue containing fillers and impurities (heavy metals). The gas fraction contains mainly methane, ethane, ethene, and propene, the oil fraction benzene, toluene, xylene, and naphthalene

Separation of high purity indole from coal tar by high pressure crystallization

High pressure crystallization has been applied to the separation and purification of indole from a model mixture of crude coal tar. Indole with 98.6 wt% purity was separated at 50 °C under a pressure of 2000 kgf cm −2 from the model mixture contaning 69.3 wt% indole. Successive ‘depressurization sweating’ increased the purity of indole up to 99.5 wt%. The equilibrium of the system under high pressure was also studied.

高炉における石炭の利用技術

This paper describes the present status of coal utilization in ironmaking.The two main processes of coal injection into blast furnace have been developed to save expensive metallurgical coke;1) The colloidal fuel mixture injection2) The pulverized coal injection (PCI)The development of the former process, that is coal oil mixture (COM) and coal tar mixture (CTM) injection into blast furnace, was completed by Sumitomo Metal Industries and other Japanese steel works in 1982.As for the latter one, the first PCI equipment in Japan has been operated in Oita No.1 BF of Nippon Steel Corporation since 1981. It was successfully completed by modifing the ARMCO system. The number of blast furnace with PCI system operation has come up to sixteen in Japan, which implies remarkable development of the system.The present technology of coal utilization in iron and steel industry is focused on the development of both coal water mixture (CWM) injection into blast furnace and coal addition into steelmaking vessels.

Thermal recycling of polymers

As most plastics are produced from oil, the recycling of plastic and rubber wastes is of increasing importance. Systems for the pyrolysis of plastic wastes with complete exclusion of oxygen use melting vessels, rotary kilns or fluidized bed processes. The pyrolysis of plastic wastes, scrap tyres and other polymeric materials in a fluidized bed has been carried out at the University of Hamburg, based on a three-step scale-up programme (laboratory plant 100 g/h, pilot plant 30 kg/h and prototype plant 150 kg/h). Up to 50% of the input plastic material is converted into liquid hydrocarbons. The product spectrum is comparable to that of a mixture of light benzene and bituminous coal tar, consisting of about 95% aromatics. By addition of lime it became possible to absorb completely the hydrogen chloride evolved from poly(vinyl chloride). The technology in a fluidized bed allows the pyrolysis of whole tyres to include aromatic compounds, gas, carbon black and steel wire. A first commercial demonstration plant using the fluidized bed process with an annual plant capacity of 5000–10,000 t has been erected.

Studies on Fatty Infiltration of the Liver Induced by Lipoid Solvents.

In a previous paper, Johnston and the author reported that fatty infiltration of the liver occurs a certain period of time after the injection of a mixture of mineral oil and coal tar into the subcutaneous tissue of rats fed a diet rich in vitamin A. We thought at that time that this mixture of lipoid solvents alone produced the fatty infiltration in these animals. More recent studies have shown that this is not true. It was a time factor only which brought about the action of the mixture of mineral oil and coal tar. Later experiments have shown that other lipoid solvents will produce the same effect in the liver after a longer interval of time. A mixture of coal tar and paraffin produces the change 30 days after the injection, coal tar in 90 days, mazola oil in 60 to 90 days, mineral oil in 45 to 60 days, and a mixture of coal tar and mazola oil in 40 to 60 days. Thus, the time of occurrence of the fatty infiltration is governed by the particular kind of lipoid solvent used. At the times given above there is an extensive infiltration involving the entire parenchyma of the liver. Previous to this time in certain of the above series a few scattered areas of vacuolization were found in a few of the livers. The infiltration does not occur in the animals fed a ration deficient in vitamin A, and only to a slight degree in the animals fed a well balanced stock ration. It does not occur in rats fed a rich vitamin A dietary that are not injected with the substances listed above. These substances are lipoid solvents.