• Korean Journal of Materials Research
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• v.26 no.9
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• pp.460-467
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• 2016

Activated carbons (ACs) have been used as EDLC (electric double-layer capacitor) electrode materials due to their high specific area, stability, and ecological advantages. In order to prepare ACs with high density and crystallinity, coal tar pitch (CTP) was activated by $K_2CO_3$ and the textural and electrochemical properties of the obtained ACs were investigated. Although the CTP ACs formed by $K_2CO_3$ activation had much smaller specific surface area and pore volume than did the CTP ACs formed by KOH activation, their volumetric specific capacitance (F/cc) levels as electrode materials for EDLC were comparable due to their higher density and micro-crystallinity. Structural characterization and EDLC-electrode performance were studied with different activation conditions of $CTP/K_2CO_3$ ratio, activation temperature, and activation period.

• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.330-336
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• 2014

Purification of indole contained in model coal tar absorption oil was examined by extraction-distillation-crystallization combination. The absorption oil consists of nine components such as four kinds of nitrogen heterocyclic compounds (9.2% quinoline, 2.4% iso-quinoline, 4.7% indole, 2.4% quinaldine), three kinds of bicyclic aromatic compounds (14.2% 1-methylnaphthalene, 31.8% 2-methylnaphthalene, 23.5% dimethylnaphthalene), 5.5% biphenyl and 3.3% phenyl ether. 99.5% indole was recovered by combination of formamide extraction-distillation-solute crystallization using n-hexane. Furthermore, the recovery process of indole contained in coal tar absorption oil was studied by using the experimental results obtained by each operation of this work.

• Corrosion Science and Technology
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• v.16 no.3
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• pp.115-127
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• 2017

Coal tar-coated pipes buried in a domestic nuclear power plant have operated under the cathodic protection. This work conducted the simulation of the coating performance of these pipes using a FEM method. The pipes, being ductile cast iron have been suffered under considerably high cathodic protection condition beyond the appropriate condition. However, cathodic potential measured at the site revealed non-protected status. Converting from 3D CAD data of the power plant to appropriate type for a FEM simulation was conducted and cathodic potential under the applied voltage and current was calculated using primary and secondary current distribution and physical conditions. FEM simulation for coal tar-coated pipe without defects revealed over-protection condition if the pipes were well-coated. However, the simulation for coal tar-coated pipes with many defects predict that the coated pipes may be severely degraded. Therefore, for high risk pipes, direct examination and repair or renewal of pipes are strongly recommended.

• Carbon letters
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• v.19
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• pp.72-78
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• 2016

Spinnable pitches and carbon fibers were successfully prepared from petroleum or coal pyrolysis residues. After pyrolysis fuel oil (PFO), slurry oil, and coal tar were simply filtered to eliminate the solid impurities, the characteristics of the raw materials were evaluated by elemental analysis, ¹³C nuclear magnetic resonance spectrometer, matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF-MS), and so on. Spinnable pitches were prepared for melt-spinning carbon fiber through a simple distillation under strong nitrogen flow, and further vacuum distillation to obtain a high softening point. Carbon fibers were produced from the above pitches by single-hole melt spinning and additional heat treatment, for oxidization and carbonization. Even though spinnable pitches and carbon fibers were processed under the same conditions, the melt-spinning and properties of the carbon fiber were different depending on the raw materials. A fine carbon fiber could not be prepared from slurry oil, and the different diameter carbon fibers were produced from the PFO and coal tar pitch. These results seem to be closely correlated with the initial characteristics of the raw materials, under this simple processing condition.

• Applied Chemistry for Engineering
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• v.18 no.2
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• pp.168-172
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• 2007

The separation of indole from a model mixture comprising four kinds of nitrogen heterocyclic compounds [indole (In), quinoline (Q), iso-quinoline (iQ), quinaldine (Qu)], three kinds of bicyclic aromatic compounds [1-methylnaphthalene (1MN), 2-methylnaphthalene (2MN), dimethylnaphthalene (DMN)], biphenyl (Bp) and phenyl ether (Pe) was examined by batch cocurrent 4 stages equilibrium extraction. The model mixture used as a raw material in this work was prepared according to the components and compositions contained in coal tar fraction (the temperature ranges of fraction: $240{\sim}265^{\circ}C$). An aqueous solution of formamide was used as a solvent. Indole was recovered more than 99% through 4 stages of the equilibrium extraction. The range of selectivity of indole in reference to DMN obtained through the 5 stages equilibrium extraction was found to be 63~118. The process for separation and recovery of indole contained in coal tar was studied by using the experimental results obtained from this work and the previous work.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.7
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• pp.3409-3416
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• 2012

Aim: It is well known that polycyclic aromatic hydrocarbons (PAHs) such as benzo (a) pyrene have carcinogenic properties and may cause many types of cancers in human populations. Genetic susceptibility might be due to variation in genes encoding for carcinogen metabolizing enzymes, such as cytochrome P-450 (CYP450). Our study aimed to investigate the effect of genetic polymorphisms of CYP1A1 (m1 and m2) on genetic damage in 115 coal-tar workers exposed to PAHs at their work place. Methods: Genetic polymorphisms of CYP1A1 were determined by the PCR-RFLP method. Comet and buccal micronucleus assays were used to evaluate genetic damage among 115 coal tar workers and 105 control subjects. Results: Both CYP1A1 m1 and CYP1A1 m2 heterozygous and homozygous (wt/mt+mt/mt) variants individually as well as synergistically showed significant association (P<0.05) with genetic damage as measured by tail moment (TM) and buccal micronuclei (BMN) frequencies in control and exposed subjects. Conclusion: In our study we found significant association of CYP1A1 m1 and m2 heterozygous (wt/mt)+homozygous (mt/mt) variants with genetic damage suggesting that these polymorphisms may modulate the effects of PAH exposure in occupational settings.

• Environmental Mutagens and Carcinogens
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• v.20 no.1
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• pp.34-39
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• 2000

Although shipbuilding workers were exposed to a variety of genotoxic compounds including polycyclic aromatic hydrocarbons (PAHs), limited number of studies were conducted to evaluate the biomarkers related to PAH exposure in painting workers in shipbuilding industry. One hundred and thirty three workers including 73 employees using coal tar paints were recruited from a shipbuilding company located in South Korea. Urinary 1-hydroxypyrene glucuronide (1-OHPG), as internal dose of PAH exposure, were measured by synchronous fluorescence spectroscopy after immunoaffinity purification using monoclonal antibody 8E11. Glutathione S-transferase (GST)M1 and GSTT1 genotypes were assessed by multiplex PCR. Information on demographic characteristics, smoking gabit, diet, job title, use of personal protective equipments were collected by self-administered questionnaire. Urinary 1-OHPG were higher in workers using coal tar paints than in workers using general paints, however, the difference was not statistically significant (p=0.20, Mann-Whitney U test). Urinary 1-OHPG levels in smokers were higher than in non-smokers (p<0.05 by Mann-Whitney U test) and there was a significant increase in urinary 1-OHPG levels with the numbers of cigarettes consumed per day (Spearman's correlation coefficient = 0.28, p=0.02). Genetic polymorphisms of GSTM1 and GSTT1 did not influence the level of 1-OHPG in study subjects. Multiple regression analysis show that smoking is the only significant predictor for lon-transformed 1-OHPG (overall model R2=0.1). These results suggest that workers using coal tar paints were exposed to significant amount of PAHs and individual difference in xenobiotic metabolism might affect the levels of internal dose of PAHs.

• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.1034-1042
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• 2012

This study was performed by using an LFR (laminar flow reactor), which can be used to carry out different types of research on coal. In this study, an LFR was used to analyze coal flames, tar and soot yields, and structures of chars for two coals depending on their volatile content. The results show that the volatile content and oxygen concentration have a significant effect on the length and width of the soot cloud and that the length and width of the cloud under combustion conditions are less than those under a pyrolysis atmosphere. At sampling heights until 50 mm, the tar and soot yields of Berau (sub-bituminous) coal, which contains a large amount of volatile matter, are less than those of Glencore A.P. (bituminous) coal because tar is oxidized by the intrinsic oxygen component of coal and by radicals such as OH-. On the other hand, at sampling heights above 50 mm, the tar and soot yields of Berau coal are higher than those of Glencore A.P. coal by reacted residual volatile matter, tar and light gas in char and flame. With above results, it is confirmed that the volatile matter content and the intrinsic oxygen component in a coal are significant parameters for length and width of the soot cloud and yields of the soot. In addition, the B.E.T. results and the images of samples (SEM) obtained from the particle separation system of the sampling probe support the above results pertaining to the yields; the results also confirm the pore development on the char surface caused by devolatilization.

• Journal of Hydrogen and New Energy
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• v.28 no.4
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• pp.323-330
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• 2017

Ash remaining after coal combustion was used as a catalyst support for tar steam reforming with various proportions of $Al_2O_3$ added for higher reforming efficiency. At a constant Ni content of 12 wt%, a coal ash and $Al_2O_3$ were mixed at a ratio of 5:5, 7:3, 9:1. As a result, the catalytic activity for toluene steam reforming was improved by adding $Al_2O_3$ at $500-600^{\circ}C$. The catalysts with ratio 7:3 and 5:5 reached toluene conversion of 100% above $700^{\circ}C$. When comparing the catalysts in which the coal ash and $Al_2O_3$ mixed at a ratio of 5:5 and 7:3 with the Ni/Al catalyst, it was concluded that this coal ash catalyst has efficient catalytic performance.

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.232-238
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• 2021

The development of a low cost catalyst with high performance and small amount of carbon deposition on catalyst from toluene steam reforming were investigated by using coal ash as a support material. Ni-loaded coal ash catalyst showed similar catalytic activity for toluene steam reforming compared with the Ni/Al2O3. At 800 ℃, the toluene conversion was 77% for Ni/TAL, 68% for Ni/KPU and 78% for Ni/Al2O3. Ni/TAL showed similar toluene conversion to Ni/Al2O3. However, Ni/KPU produced higher hydrogen yield at relatively lower toluene conversion. Ni/KPU catalyst showed a remarkable ability of suppressing the carbon deposition. The difference in coke deposition and hydrogen yield is due to the composition of KPU ash (Ca and Fe) which increase coke resistance and water gas shift reaction. This study suggests that coal ash catalysts have great potential for the application in the steam reforming of biomass tar.