Benzene Soluble Fraction Research Articles

Evaluation and Enhancement of the Performance of Benzene Solubles Methods for Asphalt Fume Assessment

Abstract A laboratory study was conducted to determine which benzene soluble fraction (BSF) analytical method—National Institute for Occupational Safety and Health (NIOSH) Method 5023 or Occupational Safety and Health Administration (OSHA) Method 58—provides the best accuracy and precision at their lower limits of detection (LODs) for measuring asphalt fume exposures. In addition, the total hydrocarbon components of asphalt fume were determined in conjunction with NIOSH Method 5023 by introducing a large charcoal tube after the filter cassette. During an asphalt industry cross-sectional exposure assessment study [Appl. Occup. Environ. Hyg. 10(10):840-848 (1995)], it was determined that the NIOSH method lacked accuracy at very low airborne concentrations. It became evident that there were background problems at the LOD when BSF results were greater than the total dust results. Laboratory static and dynamic tests were conducted to determine if BSF background contamination occurs from the benzene used for extraction, from the extraction systems, or from the filters. Once the sources of background contamination were identified, a comparison of the two analytical methods was performed. The effect of storage on the different medium types (PTFE and glass fiber) was examined, and extraction efficiencies using mineral oil spikes and laboratory-generated fumes were determined. It was concluded that NIOSH Method 5023 with modifications to reduce the BSF background provided better accuracy and precision at the LOD than OSHA Method 58 at the concentration range from 0.2 to 5.0 mg/m3. In addition, the large charcoal tube in line with NIOSH Method 5023 successfully measured the volatile components of the fume for a complete assessment of the potential hazards.

98/01245 Carbonization and graphitization behavior of iodine-treated coal tar pitch: Kajiura, H. et al. Carbon, 1997, 35, (2), 169–174

The authors investigated carbonization and graphitization behavior of coal tar pitch (CTP) treated with iodine. The behavior of weight decrease and the microstructural development with increase of heat treatment temperature were different between non-treated and iodine-treated CTP. The carbon yield of CTP increased from 40 to 70% by the iodine treatment. Flow type texture was obtained from non-treated specimen and isotropic texture was obtained from the iodine-treated one. Gas mass spectrometric analysis showed that dehydrogenative reactions were accelerated by iodine at the temperature range from 200 to 450 °C. The iodine treatment was mainly effective for the benzene soluble fraction of the CTP. The X-ray diffraction on graphitized specimens showed that the graphitizability was able to be delayed by the iodine treatment.

Serum liver function profiles in coking workers.

Coking workers are regularly exposed to coke oven emissions (COE), which consist mainly of polycyclic aromatic hydrocarbons and volatile organic compounds. In a previous cross-sectional study, we found that coking and by-product workers with heavy exposure to COE in the older of two coke operation areas in Taiwan had higher serum activities of hepatic aminotransferase than the controls. In this study, we further examine the relationship of exposure to COE with liver function profiles in coking workers. Liver function profiles included serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), alkaline phosphatase (ALP), and total bilirubin (BIL). The exposed group included 88 workers working 3 months or more in the older coke oven plant. Fifty-nine referents, not visiting the coke operation areas in the last 3 months, came from the administrative area in the same company. Each participant wore a personal monitor that was used to measure benzene soluble fraction (BSF) of total particulates, as a surrogate of COE, for 3 consecutive days between August 1995 and February 1996. Serum liver function profiles, hepatitis B surface antigens, and anti-hepatitis C antibodies were examined in the morning following the exposure measurements. Exposure levels were categorized by exposure situations (high, medium, low) among coking workers. The high exposure group (n = 23) worked topside of the oven. The medium exposure group (n = 44) worked at the sideoven for more than 4 hr/day, whereas the low exposure group (n = 21) worked at the sideoven for less than 4 hr/day and mostly remained in the control rooms. The low exposure group was used as an internal comparison group. The median BSF concentrations for various exposure situations were as follows, high exposure group: 372 micrograms/m3, medium exposure group: 61 micrograms/m3, low exposure group: 49 micrograms/m3, and referents: 10 micrograms/m3. The coking workers (n = 88) did not significantly differ from the referents (n = 59) in any of the liver function profiles. Excluding the referents, workers in the high exposure group had a mean AST level that was 31% higher (95% confidence interval (CI) = 9-57%) and a mean ALT level that was 46% higher (95% CI = 7-98%) than those in the low exposure group after adjusting for appropriate confounders in multivariate models. The prevalence of an abnormal hepatocellular pattern (AST > 37 IU/L or ALT > 39 IU/L) was more common in the high exposure group than in the low exposure group (adjusted odds ratio = 4.4; 95% CI = 0.9-22.6). However, these associations were not found in GGT, ALP, or BIL. After controlling for the possible effects of nonoccupational factors on serum activity of AST and ALT, we conclude that increased AST and ALT levels among topside coking workers may be caused by heavy inhalation exposure to COE. Additionally, the adverse hepatic effect seems to be caused by a mixture of hazards, rather than a unique identifiable chemical.

Carbonization and graphitization behavior of iodine-treated coal tar pitch

The authors investigated carbonization and graphitization behavior of coal tar pitch (CTP) treated with iodine. The behavior of weight decrease and the microstructural development with increase of heat treatment temperature were different between non-treated and iodine-treated CTP. The carbon yield of CTP increased from 40 to 70% by the iodine treatment. Flow type texture was obtained from non-treated specimen and isotropic texture was obtained from the iodine-treated one. Gas mass spectrometric analysis showed that dehydrogenative reactions were accelerated by iodine at the temperature range from 200 to 450 °C. The iodine treatment was mainly effective for the benzene soluble fraction of the CTP. The X-ray diffraction on graphitized specimens showed that the graphitizability was able to be delayed by the iodine treatment.

Application of liquid crystal theory to the estimation of mesophase pitch phase-transition behavior

The molecular field treatment developed for analysis of phase equilibria of meson-nonmesogen liquid crystal mixtures was applied to a quantitative description of the phase transition behavior of mesophase pitches, which were prepared by mixing a benzene-soluble fraction with a benzene-insoluble fraction of coal-tar pitch. The result showed that such a simplified theoretical treatment can be used to describe a phase diagram for a mesophase pitch.

Supercritical toluene extraction of a reduced Turkish lignite

Elbistan-Afsin lignite, 64.2% C (daf), was reduced with lithium in THF in the presence of purified naphthalene as an electron transfer agent. The reduced lignite was then extracted with supercritical toluene. Even under comparatively mild conditions, 340°C, relatively large yields of supercritical extract were obtained, almost all of which dissolved in benzene. The n-pentane-soluble and benzene-soluble fractions of the extract were eluted using column chromatography. Less than half of the originally soluble material could be eluted with n-pentane or benzene, the total methanol eluates amounting to 56.1% of the initial extract. The eluates were analysed by gas chromatography/mass spectrometry. The amount of phenol was 23.6% of the original benzene soluble fraction. It was concluded that bond cleavage had taken place during the reduction of the lignite. The naphthalene used as an electron transfer agent participated in side reactions.

Respirable Dust Characterization in an Indian Open-Cast Coal Mine

Abstract There has been a phenomenal increase in the production of coal from surface mines in India. Vehicular traffic on haul roads of mechanized open-cast coal mines has been identified as the most prolific source of fugitive dust. The airborne dust not only creates a serious health hazard, but also affects the productivity through poor visibility and increased maintenance cost and ultimately deteriorates the ambient air quality in and around the mining sites. An intensive study was carried out in the Muraidih Open-cast Project of Bharat Coking Coal Ltd. (Dhanbad, Bihar, India) for 1 year to characterize the airborne haul road dust. The percentage of suspended particulate matter at the various size ranges and the free silica content of each of the size ranges of haul road dust were determined. Dust particles are an obvious source of trace elements in the mines. Concentrations of nine trace elements in the haul road dust and the benzene-soluble fractions of suspended particulate matter at the various sta...

96/01362 Catalytic dehydrogenation of coal liquefied products: An alternative route to produce naphthalenes from coal

A successive two-stage hydrotreatment using a commercial Ni-Mo/Al2O3 catalyst (HDN-30) was applied to the vacuum residue of a Wandoan coal liquid to achieve high levels of hydrocracking, hydrodenitrogenation and hydrodeoxygenation. Two-stage hydrotreatment in 1-methylnaphthalene containing 20wt% fluoranthene as a solvent at solvent/coal liquid ratio of unity removed 83% (overall) of nitrogen and 90% (overall) of oxygen in the asphaltene (benzene-soluble fraction) at 380 °C for 3 h and at 420 °C for 3 under hydrogen pressure of 15 MPa and 14 MPa, respectively, while the single stage treatment at 420 °C for 3 h removed only 41% and 46%, respectively. The same two-stage treatment allowed the overall denitrogenation of 51% and the overall deoxygenation of 67% from a mixture of asphaltene and preasphaltene (THF-soluble fraction). Addition of the catalyst prior to the second stage reaction increased the removal of nitrogen and oxygen to 75 and 82%, respectively, indicating significant catalyst deactivation by the preasphaltene fraction in the first stage. Increasing the solvent/coal liquid ratio to 2 or addition of tetrahydrofluoranthene as a component of the solvent increased the removal of nitrogen and oxygen to 70 and 80%, respectively. Such two-stage hydrotreatment was also effective in refining the whole residue, allowing denitrogenations and deoxygenations of 68 and 75%, respectively using tetrahydrofluoranthene. The coke, unreacted coal and minerals in the residue may not cause acute catalyst deactivation. High dissolving ability of the reaction solvent is very effective to decrease catalyst deactivation by carbon deposition. The successive two-stage hydrotreatment also enhanced hydrocracking of polar and resin fractions in the residue into oils (conversion, 65%). The extensive hydrogenation of the former fractions in the first stage may allow more easy cracking and may suppress with the aid of solvents their irreversible adsorption on the catalyst which leads to their coking into the catalyst poisons.

96/01366 Converting synthesis gas to branched hydrocarbons

A successive two-stage hydrotreatment using a commercial Ni-Mo/Al2O3 catalyst (HDN-30) was applied to the vacuum residue of a Wandoan coal liquid to achieve high levels of hydrocracking, hydrodenitrogenation and hydrodeoxygenation. Two-stage hydrotreatment in 1-methylnaphthalene containing 20wt% fluoranthene as a solvent at solvent/coal liquid ratio of unity removed 83% (overall) of nitrogen and 90% (overall) of oxygen in the asphaltene (benzene-soluble fraction) at 380 °C for 3 h and at 420 °C for 3 under hydrogen pressure of 15 MPa and 14 MPa, respectively, while the single stage treatment at 420 °C for 3 h removed only 41% and 46%, respectively. The same two-stage treatment allowed the overall denitrogenation of 51% and the overall deoxygenation of 67% from a mixture of asphaltene and preasphaltene (THF-soluble fraction). Addition of the catalyst prior to the second stage reaction increased the removal of nitrogen and oxygen to 75 and 82%, respectively, indicating significant catalyst deactivation by the preasphaltene fraction in the first stage. Increasing the solvent/coal liquid ratio to 2 or addition of tetrahydrofluoranthene as a component of the solvent increased the removal of nitrogen and oxygen to 70 and 80%, respectively. Such two-stage hydrotreatment was also effective in refining the whole residue, allowing denitrogenations and deoxygenations of 68 and 75%, respectively using tetrahydrofluoranthene. The coke, unreacted coal and minerals in the residue may not cause acute catalyst deactivation. High dissolving ability of the reaction solvent is very effective to decrease catalyst deactivation by carbon deposition. The successive two-stage hydrotreatment also enhanced hydrocracking of polar and resin fractions in the residue into oils (conversion, 65%). The extensive hydrogenation of the former fractions in the first stage may allow more easy cracking and may suppress with the aid of solvents their irreversible adsorption on the catalyst which leads to their coking into the catalyst poisons.

96/01370 Exfoliated MoS 2 catalysts in coal liquefaction

A successive two-stage hydrotreatment using a commercial Ni-Mo/Al2O3 catalyst (HDN-30) was applied to the vacuum residue of a Wandoan coal liquid to achieve high levels of hydrocracking, hydrodenitrogenation and hydrodeoxygenation. Two-stage hydrotreatment in 1-methylnaphthalene containing 20wt% fluoranthene as a solvent at solvent/coal liquid ratio of unity removed 83% (overall) of nitrogen and 90% (overall) of oxygen in the asphaltene (benzene-soluble fraction) at 380 °C for 3 h and at 420 °C for 3 under hydrogen pressure of 15 MPa and 14 MPa, respectively, while the single stage treatment at 420 °C for 3 h removed only 41% and 46%, respectively. The same two-stage treatment allowed the overall denitrogenation of 51% and the overall deoxygenation of 67% from a mixture of asphaltene and preasphaltene (THF-soluble fraction). Addition of the catalyst prior to the second stage reaction increased the removal of nitrogen and oxygen to 75 and 82%, respectively, indicating significant catalyst deactivation by the preasphaltene fraction in the first stage. Increasing the solvent/coal liquid ratio to 2 or addition of tetrahydrofluoranthene as a component of the solvent increased the removal of nitrogen and oxygen to 70 and 80%, respectively. Such two-stage hydrotreatment was also effective in refining the whole residue, allowing denitrogenations and deoxygenations of 68 and 75%, respectively using tetrahydrofluoranthene. The coke, unreacted coal and minerals in the residue may not cause acute catalyst deactivation. High dissolving ability of the reaction solvent is very effective to decrease catalyst deactivation by carbon deposition. The successive two-stage hydrotreatment also enhanced hydrocracking of polar and resin fractions in the residue into oils (conversion, 65%). The extensive hydrogenation of the former fractions in the first stage may allow more easy cracking and may suppress with the aid of solvents their irreversible adsorption on the catalyst which leads to their coking into the catalyst poisons.

Structural analysis of mesophase pitch with high-resolution, high-temperature 13C-NMR

The structural parameters of mesophase pitch with optical anisotropy have been successfully obtained by using high-temperature 13C-NMR spectroscopy. Well-resolved spectra were obtained from the mesophase pitch with the addition of pyrene, which played the role of solvent for a quinoline-insoluble rich mesophase pitch during NMR measurement at 573 K. The resolution of NMR spectra was improved due to the decline in viscosity, without any influence on the chemical shift for aliphatic carbons. Hydrogen distribution has been converted from the intensities of aliphatic carbon obtained by a high-temperature 13C-NMR spectrum. Average structural parameters of whole mesophase pitch were calculated with the distribution of hydrogen by using Brown-Ladner equations. Structural characteristics of the benzene-insoluble fraction in two kinds of mesophase pitch have been discussed as well as that of the benzene-soluble fraction and whole pitch.

Solubilization of lignite with superacid (trifluoromethanesulfonic acid)/isopentane at the mild conditions

Abstract Trifluoromethanesulfonic acid (TFMS) was found to solubilize lignite and subbituminous coal in the presence of isopentane at temperature as low as 150°C for three hours under autogeneous pressure of 6.1–6.9 MPa without hydrogen. Yallourn coal gave 63 wt% pyridine soluble fraction after reaction and required more TFMS to achieve the maximum solubility, but the treated Taiheiyo coal could be solubilized in pyridine to the extent of 90% by the same reaction with TFMS. Acid-catalyzed depolymerization with TFMS would be inadequate, because the lignite has many oxygen containing functional groups. The average molecular weight of benzene soluble and THF soluble fraction from the treated Yallourn coal decreased, and their aromaticity increased with the increase of TFMS concentration. In contrast, average molecular weight of soluble fraction from the treated Taiheiyo coal was unchanged, and their aromaticity decreased with the increase of TFMS concentration. It is suggested that TFMS plays an important role in depolymerization of the coal molecules for Yallourn coal solubilization, and accelerates alkylation and hydrogenation in the Taiheiyo coal solubilization. Oxygen functional groups would lower the activity of TFMS as acid catalyst by interaction, leading to the formation of water from the cleavage of aliphatic ether groups and the dehydration of phenoxy OH groups.

Asphalt Industry Cross-Sectional Exposure Assessment Study

Abstract Work activities around molten or heated petroleum asphalt, such as in road paving and roofing applications, may result in worker exposure to asphalt fumes. This article presents the results from a worker exposure study, conducted in five different industries, that examined airborne and dermal exposure to asphalt fumes. The industries included road paving, hot mix plants, refineries/terminals, roofing manufacturing, and roofing application. Thirty-one sites were visited throughout the continental United States during this study. Dermal wipe samples from the back of the hand or forehead were collected from selected workers in each industry studied. Air samples were collected over full work shifts to measure concentrations of respirable particulate matter (RPM), total particulate matter (TP), benzene soluble fraction (BSF), and polynuclear aromatic hydrocarbons (PAHs). Observations were made to identify work practices, hygienic procedures, exposure control methods, and factors that could influence e...

Coal tar residues produce both DNA adducts and oxidative DNA damage in human mammary epithelial cells.

In the present study we compare the metabolic activation of coal tar, as measured by the production of both DNA adducts and oxidative DNA damage, with that of a single carcinogen that is a constituent of this complex mixture in human mammary epithelial cells (HMEC). We find that a significant level of DNA adducts, detected by 32P-postlabeling, are formed in HMEC following exposure to coal tar residues. This treatment also results in the generation of high levels of oxidative DNA damage, as measured by the production of one type of oxidative base modification, thymine glycols. The amounts of both DNA adducts and thymine varied considerably between the various coal tar residues and did not correlate with either the total amount of polycyclic aromatic hydrocarbons (PAH) or the amount of benzo[a]pyrene (B[a]P) present in the residue. Fractionating the residue from one of the sites by sequential extraction with organic solvents indicated that while the ability to produce both types of DNA damage was contained mostly in a hexane-soluble fraction, a benzene-soluble fraction produced high levels of reactive oxygens relative to the number of total DNA adducts. We find that the total amount of PAH or B[a]P present in the coal tars from the various sites was not a predictor of the level of total DNA damage formed.

Design, Analysis and Interpretation of Long-Term Mortality Studies of Coke Oven Workers

Summary This paper describes the design, analysis and interpretation of the long term mortality studies of coke oven workers conducted by the Department of Biostatistics in the Graduate School of Public Health, University of Pittsburgh. Problems related to the uncertainties associated with occupational exposure histories, industrial exposure measurements and their impact on risk estimates are discussed. Methodologies to combat these difficulties using ancillary risk factor information are suggested. The coke oven workers major cohorts consist of 1060 men employed at the coke ovens in 1953 in two major coke plants in Allegheny County, Pennsylvania and 1860 men who worked between 1951 and 1955 at the coke ovens in ten coke plants from other areas of the United States and Canada. The major comparison groups consist of 2065 men for the Allegheny County cohort and 3579 men for the Non-Allegheny County cohort, who worked in the corresponding steel plants during the same periods but never in coke oven jobs. The cohorts have been followed for mortality from 1953 through 1982. Cause-specific mortality rates within different subgroups based primarily on length of employment and type of jobs are evaluated for various phases of follow-up using summary statistics such as standardized mortality ratios and relative odds ratios. Major findings indicate a strong relationship for increased respiratory cancer risks associated with longer duration and proximity to the coke ovens and an increased risk of prostate cancer among coke oven workers. Dose-response relationships between lung cancer risks and a measure of coke oven emissions, the benzene soluble fraction of the total particulate matter, commonly known as coal tar pitch volatile (CTPV), are investigated using both regression and biologically motivated models. Results from the regression models indicate that measures of exposure rates, duration of exposure and time since exposure terminated are important predictors of cancer risks. Results from the fitting of multistage and two-mutation models indicate both initiation and promotional effects of coke oven effluent on lung cancer.

石炭液化残さ有機成分の沸点範囲

The boiling ranges of the solvent soluble fractions from coal liquefaction residues (Wandoan, Wyoming and Illinois coals) were determined by the TG method. 40-50% of the residues were dissolved into benzene and 4-5% into n-hexane. Illinois coal residue contains a slightly larger amount of benzene soluble fraction. The coal liquefaction residues showed 40-50% of weight decrease up to 800-950°C by TG at 100°C/min of heating rate under 1Torr. About 70-80% of benzene solubles were distilled up to 700°C. The n-hexane soluble fractions were the lighter ones in this study, which should contain heavier constituents than crysene by GC. It is concluded that the organic constituents from coal liquefaction residues were very heavy.

Vaporization of Graphite in Plasma Arc and Identification of C 60 in the Deposit

Vaporization of graphite in the argon‐helium plasma arc at atmospheric pressure has been carried out. Carbon soot sample was deposited on the wall of the arc chamber in a higher deposition rate. Small amounts of was identified in the product by means of visible‐UV spectroscopy and x‐ray diffraction methods. The existence of in the benzene soluble fraction of the deposit was made sure by means of Raman spectroscopy as well as by Mass spectroscopy.

New route to naphthalenedicarboxylic acids through dichromate oxidation of HS and HI/BS fractions of SRC from akabira coal.

FD-MS analysis and pyrolytic study of lighter portions of Solvent Refined Coal (SRC) showed abundance of dimethylnaphthalene derivatives in the fraction or its pyrogram, which fact suggested that these compounds are involved in a unit structure of relatively high-molecular-weight fraction, such as hexane-insoluble and benzene-soluble fraction (HI/BS) of SRC. Oxidation of hexane-soluble fraction (HS) and HI/BS of SRC at 250°C by Na2Cr2O7 produces several aromatic carboxylic acids in which naphthalenedicarboxylic acids are most abundant as expected. This result shows that many alkylaromatic compounds in the HS and HI/BS of SRC were selectively oxidized to corresponding aromatic carboxylic acids, notably yields of naphthalenedicarboxylic acids reached 9.5wt% with HS and 2.4% with HI/BS (HS and HI/BS basis, respectively). Oxidation of original coal and its extract at the same reaction conditions afforded 20% and 30% of acids products, respectively. However, naphthalenedicarboxylic acids along with other aromatic carboxylic acids as observed with the run of SRC fraction could be observed only on a slight extent. Oxidation of lighter fractions of SRC, therefore, is a promising method to directly produce naphthalenedicarboxylic acids.

“樹木バイオマスの有機化学資源としての利用研究” 第３報 爆砕処理したスギ（Ｃｒｙｐｔｏｍｅｒｉａ Ｊａｐｏｎｉｃａ Ｄ．Ｄｏｎ）材成分の溶媒抽出

A sawdust of Sugi (Cryptomeria japonica D. Don ) wood was treated under conditions of high steam pressures (2.75-2.94 MPa) at 230°C for 5-12 min and an explosive operation. The explosion products from the heart- and sap-wood were washed with water and extracted with hot benzene in order to remove a lignin-like component. The explosion treatment increased the benzene-soluble fraction as well as the methanol extracts. From the benzenesoluble fraction, vanillin 1, coniferyl aldehyde 2, and unidentified phenolic compounds were isolated along with sandaracopimaric acid 3, sandaracopimarinal 4, sandaracopimarinol 5, ferruginol 6, and β-sitosterol.

The sampling of coke oven emissions for polycyclic aromatic hydrocarbons: a critical review

Polycyclic aromatic hydrocarbons (PAHs) are believed to be among the most harmful organic compounds emitted from coke ovens. Awareness of occupational health hazards is increasing and long-term monitoring of worker exposure to PAHs is becoming mandatory. We review the methods that have been used for sampling airborne PAHs at coke ovens, discuss the sources of sampling error and suggest the manner in which better sampling devices might be constructed. Sampling is usually performed by filtration (e.g. ‘benzene soluble fraction’ test) or by filtration followed by back-up collection using a solid adsorbent. Errors arise from incomplete trapping of material, evaporative losses, chemical degradation or incomplete recovery. We indicate the ways in which these errors may be minimized and point to areas where further work is required. Sampling is the most neglected stage in the analysis of airborne PAHs and new methods are required to satisfy the needs of industrial hygienists in the coking industry.