• Clean Technology
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• v.13 no.1 s.36
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• pp.72-78
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• 2007

As a basic research fur the separation of effective components included in pyrolysis gas oil, the crystallization on each system of naphthalene with 2-methylnaphthalene, indene and 1-methylnaphthalene as impurity has been carried out in column and cold-finger type crystallizer, respectively. In crystallization operation, the purity of naphthalene has been a tendency of increase with decreasing of cooling rate and in the presence of impurity with lower melting point. In comparison of crystallizer types, naphthalene purity in column type crystallizer was a higher value than that in cold-finger type due to effective sweating operation after crystallization.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.238-241
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• 2010

The purification of indole from 54.3wt% indole fraction (temperature range of distillate: $250{\sim}255^{\circ}C$) recovered by extraction-distillation combination of coal tar fraction (temperature range of distillate: $240{\sim}265^{\circ}C$) was examined by solute crystallization. The feed consists of eight components such as quinoline, iso-quinoline, indole, quinaldine, 1-methylnaphthalene, 2-methylnaphthalene, biphenyl and phenyl ether. Hexane and an aqueous solution of methanol (50 : 50 vol%) were used as the crystallization solvent and the coolant, respectively. A batch stirred tank of glass material was used as a crystallization apparatus. By increasing the operation temperature and the volume ratio of solvent to feed at initial, the purity of indole increas ed, but yields of indole showed a decreasing tendency. Solute crystallization method using hexane as a solvent was excellent because the purity of 99.3 wt% indole was recovered at the yield of 50% without washing operation.

• Applied Chemistry for Engineering
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• v.33 no.5
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• pp.477-481
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• 2022

As a part of improving the quality of crude methylnaphthalene (CMNO), this study was experimentally examined the reduction of nitrogen-containing compounds (NC) present in the CMNO by solvent extraction. The CMNO was composed of three kinds of NC [quinolone (QU), iso-quinoline (IQU), indole (IN)], three kinds of bicyclic aromatic compound [BAC; naphthalene (NA), 1-methylnaphthalene (1MNA), 2-methylnaphthalene (2MNA)] and biphenyl (BP) etc., in addition to an aqueous formamide solution, which were used as raw materials and a solvent, respectively. The increase in the volume fraction of water to the solvent in the initial state (y_w,0) caused a sharp decrease in the distribution coefficient and the yield of NC, but conversely raised the increased selectivity of NC based on 2MNA. The compositions of QU, IQU and IN in the raffinate oil recovered through the equilibrium extraction of batch co-current 5-stage under constant conditions [y_w,0 = 0.1, volume fraction of solvent to feed (CMNO) at the initial state = 1, operating temperature = 303 K, liquid-liquid contacting time = 72 h] were reduced by about 51.5%, 55.2%, and 71.8%, respectively, when compared to those of CMNO. From the excellent reduction rate of NC, the formamide extraction method suggested in this study can be expected to be a useful reduction method for NC contained in the CMNO.

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.142-146
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• 2014

The separation of nitrogen heterocyclic compound (NHC) contained in a model coal tar fraction of nine components system was investigated by distribution equilibrium. The model coal tar fraction comprising NHC group (NHCs; indole (In), quinoline (Q), iso-quinoline (iQ), quinaldine(Qu)), bicyclic aromatic compound group (BACs; 1-methylnaphthalene (1MN), 2-methylnaphthalene (2MN), dimethylnaphthalene (DMN)), biphenyl (Bp) and phenyl ether (Pe) and the aqueous methanol were used as the raw materials and the solvent of this work, respectively. A batch-stirred tank was used as the liquid-liquid contact unit of this work. The distribution coefficient of NHCs increased by increasing the equilibrium operation temperature, whereas the selectivity of NHCs with respect to BACs decreased. Decreasing the initial volume ratio of water to the solvent resulted in deteriorating the selectivity of NHCs in reference to BACs, but improving the distribution coefficients of NHCs. At a fixed experimental condition, the sequence of the distribution coefficient and the selectivity with reference to BACs for each groups was increased in order of NHCs > Bp > BACs > Pe and NHCs > Bp> Pe, respectively. Also, the sequence of the distribution coefficient for entire compounds was in order of In > iQ = Q > Qu > Bp > 1MN = 2MN > Pe > DMN. The maximum yield of NHCs and the selectivity of NHCs based on BACs obtained by methanol extraction were 94 and 23%, respectively. Furthermore, the recovery process for NHCs from coal tar was studied by using the experimental results from this work.

• Applied Chemistry for Engineering
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• v.34 no.6
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• pp.665-669
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• 2023

The crude methylnaphthalene oil (CMNO) contains nitrogen compounds (NCs) such as quinoline (QU), isoquinoline (IQU), and indole (IN). These NCs in the CMNO are treated as impurities contained in the CMNO due to contamination of the atmospheric environment and unpleasant odors. In order to improve the quality of CMNO, this study examined the effect of extraction experimental factors on the reduction of NCs contained in CMNO using CMNO as a raw material and an aqueous formamide solution as a solvent, respectively. The increase in the volume ratio of solvent to feed in initial (S/F)₀ in initial increased the distribution coefficient of NCs and the selectivity of NCs in reference to 2-methylnaphthalene (2MNA). Additionally, an increase in operating temperature (T) increased the distribution coefficient of NCs but conversely decreased selectivity. The compositions of QU, IQU, and IN in the raffinate oil recovered through equilibrium extraction under a constant condition (volume fraction of water to solvent in initial (y_w,0) = 0.1, (S/F)₀ = 9, T = 303 K, liquid-liquid contacting time = 72 h) were reduced by about 58.5 wt%, 61.9 wt%, and 73.4 wt%, respectively, compared to those of CMNO. The formamide extraction method in this study was expected to be an effective reduction method for NCs contained in CMNO.

• 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.

• The Korean Journal of Malacology
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• v.30 no.3
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• pp.177-187
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• 2014

Mussels have been commonly used in bioassay for quality assessments of environment. Moreover, several standard protocols for the developmental bioassay of bivalves have been proposed. In this study, the EC50 of polycyclic aromatic hydrocarbons (PAHs) was determined using mussel, Mytilus galloprovincialis embryonic developmental bioassay. To determine the sensitivity of M. galloprovincialis, their fertilized eggs were exposed to five PAHs (2-metylnaphthalene, fluorene, dibenzothiophene, phenanthrene, pyrene). The EC50 of 2-metylnaphthalene, fluorene, dibenzothiophene, phenanthrene, and pyrene were 232, 273, 67.9, 43.2, and $33.1{\mu}g/L$, respectively. The overall sensitivity of M. galloprovincialis in the present developmental bioassay was similar to or more sensitive than that of other marine organisms commonly used in aquatic bioassays. The results of this study could be provide with fundamental data of setting standard for protection of marine life and or can use prediction the aquatic toxicity of PAHs.

• Rapid Communication in Photoscience
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• v.4 no.2
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• pp.31-33
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• 2015

Fluorescence (FL) properties of a novel donor-acceptor dyad, comprised of mesitylene and 1,4-dicyano-2-methylnaphthalene (DCMN) subunits connected by an ether linkage, were elucidated. The dyad in cyclohexane exhibits FL arising from an intramolecular exciplex. In the crystalline state, the dyad does not emit light from intra- and inter-molecular exciplexes but rather displays FL that is nearly equivalent to that of 2-methoxymethyl-substituted DCMN. However, the emission spectrum of the crystalline dyad contains a shoulder in the long wavelength region, suggesting that weak intercolumnar charge-transfer interactions take place between columns consisting of the mesitylene and DCMN subunits.

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.863-870
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• 1999

The catalytic performance of Co-Mn-Br system was performed in the 2,6-dimethylnaphthalene(DMN) oxidation at relatively mild reaction conditions such as $160^{\circ}C$ and $6kg/cm^2$. Experiments were conducted using a $2{\ell}$ batch reactor with varying the concentrations of catalysts. The reaction route of DMN oxidation was considered by measuring the concentration of intermediate species. As the intermediate species, 2-formyl-6-naphthoic acid, 2-methyl-6-naphthoic acid and 2-hydroxymethyl-6-methylnaphthalene are found. It was found that the yield of 2,6-naphthalene dicarboxylic acid(NDA) is largely dependent on the Co and Br concentrations. In addition, it was observed that color-b was closely related with Mn concentration in this experimental range. The burning loss of solvent could be reduced by controlling the concentration of Mn and Br. Addition of small amount of Ce and Cu compounds led to increase the NDA yields and decrease the burning amount of solvent.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.166-172
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• 2022

A method of efficiently purifying high value-added indole among components of coal tar absorption oil was studied using a step-by-step process of extraction-distillation-crystallization. The coal tar absorption oil used in this study contains 1.2% naphthalene, 0.1% quinoline, 0.4% isoquinoline, 6.4% indole, 21.0% 1-methylnaphthalene, 48.8% 2-methylnaphthalene, and 11.7% biphenyl as main components. For the separation and purification of indole, methanol was first used as a solvent to separate indole species in the coal tar absorption oil into an extract phase. And then methanol was recovered by distillation. Subsequently, an extraction solution where methanol was removed was mixed with normal hexane, and then crystallized to recover indole having a purity of 99.3%. Based on the experiments of this study, a purification process scheme for indole in coal tar absorption oil was proposed.