Tar Products Research Articles

Fluorescence spectroscopic analysis of benzo[ a]pyrene in coal tar and related products

Direct quantitative fluorescence spectroscopic analysis of benzo[ a]pyrene in coal tar, without sample fractionation, was shown to be valid by analysis of a standard reference coal tar (with certified concentrations for 12 polycyclic aromatic hydrocarbons) and a mixture of 16 polycyclic aromatic hydrocarbons of known concentration. This simple and rapid method was applied to the analysis of benzo[ a]pyrene in coal-tar pitch, a coal-tar-derived heavy residual oil, coal-tar pitch fractions and the volatiles from heat treatment of pitch (both coal-tar and petroleum). However, high values were obtained for the analysis of perylene in the same samples due to the presence of benzo- and dibenzoperylenes with similar spectra to perylene.

Site characterization of polluted soils and comparison of screening techniques for heavy metals by mobile ICP-MS, [formula omitted] (fixed laboratory) and EDXRF (fixed laboratory)

A disused industrial/mining site in the former DDR was chosen to evaluate the performance of a mobile laboratory equipped with inductively coupled plasma-mass spectrometry (ICP-MS) by comparing the results with fixed-lab based ICP-AES GFAAS and XRF. New rapid digestion methods were used to rapidly recover the metals from complex soil matrices for ICP-MS analysis in less than 6 h which permitted fast-screening of samples. Hot aqua-regia (180°C), with addition of perchloric acid appears to be a better medium for rapidly extracting heavy metals than a hot (180°C) nitric acid leach. ‘Hot spot’ identification of heavy metal anomalies were located quickly and the environmental assessment report accomplished within weeks of the field-based analyses. The precision on standard soil reference materials run by ICP-MS for Be, V, Cr, Mn, Co, Cu, Zn, As, Cd, Pb and Ni in the European Community's Advanced Mobile Analytical Laboratory (AMAL) is better than results for ICP-AES GFAAS (except for Be, Mn, and Zn), and as good as XRF for low-medium contamination. Generally, the results obtained for the partial digestion using aqua-regia compare favourably with the range for aqua-regia soluble values published for the reference materials (BCR-144, CRM-320 and BCR-142) for Cr, Ni, Pb, Cu, occasionally Zn; however, not all metals are favourable (Cd, Co, Mn ± Zn). The measured element concentrations for nitric acid partial digestion have a small negative to large negative bias compared to the BCR leach values partly because the fraction of the sample carrying the metals is not fully leached and the metal yields vary according to the concentration and solubility of the metal in the soil. The source of the contamination appears to be from lignite mining dumps and tar products of the coking industry which were operating in this part of the former DDR from the late 19th Century until 1931. A sampling grid was set up over the contaminated area and soil samples taken adjacent to a tailings dump are characterized by high V (> 140 mg/kg), Mn (> 600 mg/kg), Cr (> 60 mg/kg), Co (> 35 mg/kg), Cu (> 30 mg/kg), Zn (> 300 mg/kg), As (> 60 mg/kg), Sb (> 3 mg/kg), Ba (> 400 mg/kg), and Pb (> 40 mg/kg) leading to high levels of toxicity on the mine dumps, and responsible for the lack of vegetation presently experienced by the mine site.

Thermochemical transformation of the quinoline-soluble portion of coal tar pitch

The quinoline-soluble portion of coal tar pitch and products of its carbonization at 250, 350 and 450°C were subjected to chemical study. The structural transformations were followed by extraction and chemical and number-average analyses. The samples under study, i.e. asphaltenes + preasphaltenes and carboids, were non-reductively alkylated in the system n-BuLi-BuI. The modification improved the solubility, owing to addition of 6–7 butyl groups per 100 carbon atoms. The alkylation procedure was considered mild, in so far as it affected only the ‘acidic’ centres in the pitch and did not alter the condensed aromatic systems. A set of structural parameters was calculated. Chemical transformations for carbonization temperatures > 350°C were established as an abrupt increase in carboid content, an increase in aromaticity and degree of condensation of the aromatic structures, intense cleavage of ether bridges, their replacement by phenolic OH groups, and further rearrangement of oxygen in cyclic form.

Urinary 1-naphthol and 1-pyrenol as indicators of exposure to coal tar products.

Chemical exposure of assemblers handling creosote-impregnated wood and of a single worker chiselling coal tar pitch layer was assessed by measuring airborne naphthalene and various polycyclic aromatic hydrocarbons (PAHs), and by measurement of urinary excretion of 1-naphthol and 1-pyrenol. The sum concentration of PAHs and of 4-6 aromatic ring-containing PAHs were high, 440 micrograms/m3 and 290 micrograms/m3, respectively, when chiselling. In the assembler's workplace, the PAH concentrations were about 1/50 of this value. Regarding airborne naphthalene concentrations the situation was reversed (assemblers, 1000 micrograms/m3; chiseller, 160 micrograms/m3). Correspondingly, the assemblers' urinary 1-napthol concentrations were 15-20 times higher than those of the chiseller. The urinary 1-pyrenol concentration of the chiseller was 2-4 times higher than among the assemblers. As the estimated pyrene inhalation doses among the assemblers could account for only about 2%-25% of the 24-h pyrenol excretion in urine, the skin was presumably the main route of uptake. For an assessment of the exposure to PAHs, air measurements, monitoring of metabolites in urine and preferably also data on the composition of the skin-contaminating product are needed.

95/01241 Treatment of tar, tar-containing, wastes, and similar products to produce solid fuel

95/01241 Treatment of tar, tar-containing, wastes, and similar products to produce solid fuel

95/01437 Tar hyrdogenation products - raw materials for manufature of aromatic hydrocarbons

95/01437 Tar hyrdogenation products - raw materials for manufature of aromatic hydrocarbons

Biodiesel in Europa 1994

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Effects of organic chlorine on the chemical composition and carbon number distribution of pyrolysis tars

In order to quantify the effects of chlorine on the composition and distribution of tar products, droplets containing varying amounts of toluene and chlorinated hydrocarbon additives were pyrolyzed in nitrogen. Three chlorinated organics were studied: o-dichlorobenzene, 1,2-dichloroethane, and trichloroethylene. It was found that the pyrolysis of chloro-organics results in the sequestration of hydrogen, leading to (1) a higher propensity for soot formation, (2) a higher degree of ring fusion of the aromatic compounds produced, and (3) little chlorination of arenes at low Cl H molar ratios. More specifically, little aryl chlorine was found in tars from pyrolysis at high temperatures with Cl H < 0.3 , and most of the aryl chlorine that was detected was bound to unfused benzene rings. Pyrolysis of fuels with higher chlorine content ( 0.3 < Cl H < 0.6 ) produced tars containing significant quantities of monochlorinated and dichlorinated aromatics; in these tars, the extent of chlorine substitution decreased as aromatic carbon number increased. At a very high fuel chlorine level ( Cl H = 3 ), perchloroaromatics of low carbon number were formed almost exclusively. With regard to aromatic structure, the formation of peri-fused aromatics, including cyclopenta[cd]pyrene, and soot was favored with increasing fuel chlorine content. These results demonstrate that the role of organic chlorine in pyrolysis is governed by its preferential incorporation into HCl due to the relative instability of carbonchlorine and chlorinechlorine bonds at high temperatures.

The Chemical Society of London and the Dye Industry in the 1860s

UNTIL now the question of the relationship between science and industry, especially within the context of Britain's industrial decline after 1850, has been dominated by debates over the role of education. 1 This paper explores the possibility that, in the case of the growing sciencebased chemical industry, the answer may lie elsewhere, namely in the increasing division of interests between northern manufacturers and London-based gentlemen of science. Such considerations did not apply in 184I, the year of the formation of the Chemical Society of London, whose promoters expected that both science and its application might be served through formal sharing of new knowledge. Indeed, the journal of the new society included many important contributions from members engaged in industrial activities. This marriage of science and industry heralded the creation of London's Royal College of Chemistry,2 opened in 1845, and also gave inspiration to its teaching curriculum.3 Yet within a decade the college had fallen on hard times, and only managed to survive by merging with the Government School of Mines in 1853. Part of the problem was that academic chemists and members of the Chemical Society were concentrated in London, while the main sites of industrial activity were far to the north. Increasingly, south Lancashire was becoming the centre of the British chemical industry. London was not devoid of innovative chemical industry, but the activities were diverse and generally small scale, including the preparation offine chemicals for photography. The preparation of natural dyestuffs and drugs was of even greater importance. Such activities were prominent in the syllabus of the Royal College of Chemistry,4 and the research programmes of ·its principal, August Wilhelm Hofmann. Around 1860, chemical explanation based on Hofmann's theoretical contributions and research work almost unexpectedly became the support mechanism for a new industry that was at first led by many of his former students and assistants, and drew heavily on his two decades of research into coal tar products.

Investigation on the carcinogenic effects of coal tar pitch in rat respiratory tract by intratracheal instillations

The effects of coal tar pitch (CTP) on the tracheobronchial mucosa of Wistar rats were studied. Three groups of animals received 10 weekly intratracheal instillations of CTP at the cumulative doses of 6.48, 136.56 and 200 mg respectively. The control group of rats received 10 weekly intratracheal instillations of charcoal powder at a cumulative dose of 20 mg. The study in which the animals were killed serially revealed that CTP had conspicuous damage on the respiratory system of rats, especially on the bronchiolo-alveolar areas. The lesions induced by CTP ranged from hyperplastic, metaplastic and dysplastic changes to extensive cancers. These lesions were usually multifocal, and were more severe in the rats receiving higher dosages of CTP. The deposition of CTP particles within or adjacent to these lesions could be readily identified. Lung cancers occurred in 12.5% (4/32) and 25% (10/40) of the rats treated with 136.56 and 200 mg of CTP, whereas no tumors were found in control rats and the rats that received 6.48 mg of CTP. The overall cancer incidence significantly related to the cumulative dose of CTP. The histological types of lung cancers consisted of squamous cell carcinomas (10 out of the 14 lung cancers), adenocarcinoma (1/14), and combined squamous and adenocarcinomas (3/14). The development of CTP-induced rat lung cancers appears to derive from the hyperplasias of bronchiolo-alveolar epithelium, and processing stages of squamous metaplasias and/or dysplasias to carcinomas. The present results confirmed the carcinogenic effects of CTP on the respiratory system of rats, and provided experimental evidence for human lung carcinogenesis, particularly in those occupationally exposed to coal tars or tar products.

Formation of PCBs and other biaryls during pyrolysis of o-dichlorobenzene and toluene

The role of aryl dimerization in the pyrolysis of single ring aromatic compounds was studied by the non-oxidative heating of droplets of o -dichlorobenzene, toluene, and an equal volume mixture of o -dichlorobenzene and toluene in a drop-tube reactor at temperatures ranging from 1100 to 1500 K. During pyrolysis of o -dichlorobenzene at low temperatures (below 1400 K), aryl-aryl reactions were dominant, as expected. Product tars were comprised almost entirely of a small set of polychlorinated biphenyls (PCBs) whose relative yields were consistent with steric considerations. Little evidence of ring rupture was found. In contrast, o -dichlorobenzene pyrolysis at 1460 K produced a broad distribution of fused ring structures of even carbon number, suggestive of growth by acetylene addition. PCB yields in this tar were very low. Pyrolysis of toluene, on the other hand, resulted in a broad distribution of tar products at all temperatures studied, indicative of the ease with which reactive fuel fragments were produced. Major products included both fused ring structures and dimers of stable aryl radicals of odd carbon number (e.g., benzyl, indenyl and fluorenyl). Pyrolysis of the fuel mixture produced tars much more like those of toluene than those of o -dichlorobenzene. Thus, the presence of acyclic fragments was found to suppress PCB formation but not biaryl formation involving stable aryl radicals. With regard to fuel chlorine effects on pyrolysis product yields, we found that aryl chlorine was bound preferentially to unfused rings and fused arenes of low carbon number. We also found that the presence of chlorine increased arene reactivity, promoting the formation of highly fused aromatic products and soot.

石炭の急速水素化熱分解 イオン交換法による金属の触媒効果

Effects of various metal ions like K, Na, Ca, Fe and Ni, which were loaded to Loy Yang brown coal by ion-exchange method, on flash hydropyrolysis were investigated, using a heated grid reactor.Raw coal and coal in metal forms were heated in 70 atm hydrogen at 500°C/s to temperatures of up to 1000°C and the yields of char, tar and individual gaseous products were determined as a function of temperature history. It was found that alkaline or alkaline-earth metals showed little catalytic effect, whereas Ni and Fe significantly promoted hydropyrolysis of coal. The addition of 7.3‰ Ni resulted in the increase of the overall carbon conversion and carbon conversion to liquids by 15‰ and 5‰ respectively. Carbon conversion to methane increased by 10‰, whereas carbon conversion to benzene 3.5‰ only below 800°C . The overall carbon conversion increased by 10‰ in the case of 4.3‰ Fe-loading and further increase by 20‰ was observed when increasing Fe loading to 8.5‰. This increase was mainly due to the production of liquids. At the same time, the increases in methane and benzene were. also achieved.

Product yields and kinetics from the vapor phase cracking of wood pyrolysis tars

AbstractThe homogeneous vapor phase cracking of newly formed wood pyrolysis tar was studied at low molar concentrations as a function of temperature (773–1,073 K), at residence times of 0.9–2.2 s. Tar conversions ranged from about 5 to 88%. The tars were generated by low heating rate (0.2 K/s) pyrolysis of ∼2 cm deep beds of sweet gum hardwood, and then rapidly conveyed to an adjacent reactor for controlled thermal treatment. Quantitative yields and kinetics were obtained for tar cracking and resulting products formation. The major tar conversion product was carbon monoxide, which accounted for over two‐thirds of the tar lost at high severities. Corresponding ethylene and methane yields were each about 10% of the converted tar. Coke formation was negligible and weight‐average tar molecular weight declined with increasing tar conversion. A first‐order distributed activation energy model more closely correlated tar conversion kinetics over a wider range of reaction conditions than did a single‐reaction model.

Evaluation of a low to middle tar/medium nicotine cigarette designed to maintain nicotine delivery to the smoker

A specific objective of this 6-week crossover study was to determine how 21 regular smokers of middle tar cigarettes changed their smoking behaviour and uptake of smoke constituents, when switching to either lower tar cigarettes capable of delivering amounts of nicotine similar to a conventional middle tar cigarette (maintained nicotine product), or to conventional low tar/low nicotine cigarettes. Subjects visited the laboratory every 2 weeks for detailed assessment of their smoking behaviour. Weekly per capita consumption was similar for all three cigarettes. They were smoked with variable intensities (low tar greater than maintained nicotine greater than middle tar), the tendency being for larger puff volumes, faster puffing and increased puff duration with the low tar cigarettes. The maintained nicotine cigarette was preferred to the middle tar cigarette, although acceptability ratings of the three cigarettes only differed marginally. The nicotine absorbed from the maintained nicotine and middle tar cigarettes was similar and significantly greater than the levels achieved from the low tar cigarettes. Intake of carbon monoxide into the mouth and absorption into the blood stream was lower for the maintained nicotine cigarette than for the middle tar cigarette, with the low tar cigarette occupying an intermediate position. Derived estimates of tar intake suggested reduced intake of tar into the respiratory tract (around 25%) from the maintained nicotine product relative to the middle tar product. The possible advantages of switching to maintained nicotine cigarettes is discussed.

An English factor at stockholm in the 1680's

Abstract Some twenty years ago Professor Sven-Erik Åström set out the main features of trade between England and Sweden in the late seventeenth century, showing how the period 1670–1700 saw a marked shift from the situation prevailing earlier in the century, when English exports of cloth to the Baltic largely balanced imports of iron, to one in which Swedish exports of both iron and other goods greatly outweighed imports, thus creating a large and long-standing imbalance of trade that so concerned English merchants and economists throughout the eighteenth century.1 Åström had of necessity to rely largely on the English port books, the Stockholm weigh-books and other customs material, and the Danish Sound Toll accounts, together with contemporary literary comments, since he was unable to discover any seventeenth-century merchants’ accounts either in England or Sweden. Recently, however, a number of volumes have come to light which form a substantially complete series of journals and ledgers, together with some cash accounts and memoranda, kept by a provincial English merchant named William Hodgkinson, who traded with the Baltic and the Netherlands between about 1690 and 1730.2 This archive appears to be a unique source for the examination in detail at first hand of, the activities of a merchant engaged in the whole range of Baltic trades — iron, tar, flax, timber, hemp and other products — as well as the export of Derbyshire lead both to the Low Countries and the Baltic. A full examination of this material will be the work of some years, but one particular feature of the earliest volume warrants separate treatment.

Population based mortality surveillance in carbon products manufacturing plants.

The utility of a population based, corporate wide mortality surveillance system was evaluated after a 10 year observation period of one of the company's divisions. The subject population, 2219 white male, long term employees from Union Carbide Corporation's carbon based electrode and specialty products operations, was followed up for mortality from 1974 to 1983. External comparisons with the United States male population were supplemented with internal comparisons among subgroups of the study population, defined by broad job categories and time related variables, adjusting for important correlates of the healthy worker effect. Significant deficits of deaths were observed for all causes and the major non-cancer causes of death. The numbers of deaths due to malignant neoplasms and respiratory cancer were less than, but not statistically different from, expected. There was a non-significant excess of deaths from lymphopoietic cancer, occurring predominantly among salaried employees. When specific locations were examined, operations with potential exposure to coal tar products exhibited a mortality pattern similar to that of the total cohort. The risk for lung cancer was significantly raised (five observed, 1.4 expected) in one small, but older, location which did not involve coal tar products during the period of employment of these individuals, but which historically used asbestos materials for several unique applications. Although these findings are limited by small numbers and a short observation period, the population based surveillance strategy has provided valuable information regarding the mortality experience of the population, directions for future research, and the allocation of epidemiological resources.

KINETICS OF ADSORPTION OF ORGANICS FROM WATER PRODUCED DURING IN SITU TAR SANDS EXPERIMENTS

The adsorption characteristics of dissolved organic matter onto activated carbon from tar sand product waters were investigated in this study. Equilibrium isotherms obtained at 278 and 298 K were nonlinear over the entire liquid concentration range. Breakthrough curves were obtained in packed bed experiments as a function of bed length, particle size, and liquid velocity. The breakthrough curves were analyzed to establish the relative importance of the various individual mechanisms that contributed to the overall adsorption process.

Hydropyrolysis of coal in the presence of steam

Hydropyrolysis of Godavari (Indian) coal has been performed at 650 °C using 3 K min −1 heating rate in the presence of a mixture of steam and hydrogen in different ratios at 66 bar pressure. The yields of tar products were enhanced in the presence of steam. The use of red mud as a catalyst further enhanced the tar yields of hydropyrolysis in a mixture of hydrogen and steam. It has been demonstrated that synthesis gas could also be utilized for the hydropyrolysis of coal in the presence of steam. These studies suggest that economies in the use of hydrogen in the hydropyrolysis of coal can be made by using steam and synthesis gas.

Mutations in tar suppress defects in maltose chemotaxis caused by specific malE mutations.

Maltose-binding protein (MBP), which is encoded by the malE gene, is the maltose chemoreceptor of Escherichia coli, as well as an essential component of the maltose uptake system. Maltose-loaded MBP is thought to initiate a chemotactic response by binding to the tar gene product, the signal transducer Tar, which is also the aspartate chemoreceptor. To study the interaction of MBP with Tar, we selected 14 malE mutants which had specific defects in maltose taxis. Three of these mutants were fully active in maltose transport and produced MBP in normal amounts. The isoelectric points of the MBPs from these three mutants were identical to (malE461 and malE469) or only 0.1 pH unit more basic than (malE454) the isoelectric point of the wild-type protein (pH 5.0). Six of the mutations, including malE454, malE461, and malE469, were mapped in detail; they were located in two regions within malE. We also isolated second-site suppressor mutations in the tar gene that restored maltose taxis in combination with the closely linked malE454 and malE461 mutations but not with the malE469 mutation, which maps in a different part of the gene. This allele-specific suppression confirmed that MBP and Tar interact directly.

THE DETERMINATION OF WATER IN BIOMASS-DERIVED LIQUID FUELS

ABSTRACT The Dean and Stark distillation is an appropriate method for the determination of water in coal tar, bitumen and petroleum-like products. This article shows, however, that a direct application of the Dean and Stark method for the determination of water in biomass-derived liquid fuels results in incorrect estimates. Inaccuracies are due to the presence of soluble organics in the aqueous phase, which apparently form azeotropic mixtures with water and xylene and which condense and are trapped as distillate in the graduated cylinder. Instead, a Karl Fischer determination of water is recommended in the case of biomass-derived liquid fuels