• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2004.11a
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• pp.151-154
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• 2004

• Journal of the Korean Applied Science and Technology
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• v.24 no.4
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• pp.383-392
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• 2007

This paper is studied on the efficient purification process of dimethyl carbonate (DMC) from the melt layer crystallization combining crystallization process, sweating process and distillation recovery process. Purity and yield of DMC crystal depended mainly on the crystallization temperature, cooling rate, sweating termperature sweating rate. Through the optimization of crystallization and sweating operation, DMC crystal can be upgraded to very high purity over 99.9% and high yield over 85%.

• 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.

• Korean Journal of Metals and Materials
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• v.50 no.12
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• pp.907-911
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• 2012

High purity silicon can be obtained from Al-Si alloys by a combination of solvent refining and centrifugation. Silicon purification by crystallization of silicon from an Al-Si alloy melt was carried out using 2N and 4N purity aluminum and 2N purity silicon as raw materials. The effect of the purity of raw materials on the final silicon ingot purity by centrifugation was investigated for an Al-50 wt% Si alloy. Alloys were melted using an electrical resistance furnace, and then poured into a centrifuging apparatus. A silicon lump like foam was obtained after centrifugation and was leached by an acid in order to get pure silicon flakes. Then silicon flakes were melted to make a silicon ingot using an induction furnace. The purities of the silicon flakes and silicon ingot were enhanced significantly compared to those of the raw materials of silicon and aluminum. The silicon ingot made of 4N aluminum and 2N silicon showed the lowest impurities.

• Korean Journal of Materials Research
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• v.28 no.12
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• pp.732-737
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• 2018

We develop a purification process of $Hg_2Br_2$ raw powders using a physical vapor transport(PVT) process, which is essential for the fabrication of a high performance acousto-optic tunable filter(AOTF) module. Specifically, we characterize and compare three $Hg_2Br_2$ powders: $Hg_2Br_2$ raw powder, $Hg_2Br_2$ powder purified under pumping conditions, and $Hg_2Br_2$ powder purified under vacuum sealing. Before and after purification, we characterize the powder samples through X-ray diffraction and X-ray photoelectron spectroscopy. The corresponding results indicate that physical properties of the $Hg_2Br_2$ compound are not damaged even after the purification process. The impurities and concentration in the purified $Hg_2Br_2$ powder are evaluated by inductively coupled plasma-mass spectroscopy. Notably, compared to the sample purified under pumping conditions, the purification process under vacuum sealing results in a higher purity $Hg_2Br_2$ (99.999 %). In addition, when the second vacuum sealing purification process is performed, the remaining impurities are almost removed, giving rise to $Hg_2Br_2$ with ultra-high purity. This high purification process might be possible due to independent control of impurities and $Hg_2Br_2$ materials under the optimized vacuum sealing. Preparation of such a highly purified $Hg_2Br_2$ materials will pave a promising way toward a high-quality $Hg_2Br_2$ single crystal and then high performance AOTF modules.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.9-17
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• 2016

A purification method was established for high-purity chondroitin sulfate from skate cartilage. Hydrolytic extraction of skate backbone cartilage was investigated with the proteases alcalase and protamex, and the extraction contents of chondroitin sulfate were measured with several physicochemical processes. The yield of extract from skate cartilage with $40^{\circ}Brix$ concentration was 23.3% with 2% alcalase hydrolysis, which was decreased to 8.47% and 3.37% with the first and second additional ethanol purifications, respectively. The yield was 16.62% with one ethanol purification after hydrolysis with a mixture of 1% alcalase and 1% protamex. The content of chondroitin sulfate was measured as 39.88-45.08% with different ratios of ethanol solvent. The content was 42.92% at a solvent ratio of 1:1 with alcalase protease and 45.08% with a ratio of 1:2 using a protease mixture of alcalase and protamex. The molecular weight range of chondroitin sulfate was about 110-310 thousand Da, and the purity of chondroitin sulfate was 24.87-49.92% with a mixture of alcalase and protamex in GPC analysis. The maximum purity of chondroitin sulfate was 53.93% after ultrafiltration. The odor strength of chondroitin sulfate was decreased by 33% and 38% after ethanol purification and additional filtration with activated carbon, respectively. The odor concentration of ammonia and TMA from chondroitin sulfate was decreased by 52.1% and 37.89% with activated carbon filtration and two ethanol purifications, respectively, but it was necessary to eliminate the odor components efficiently using additional physicochemical processes.

• Journal of Korea Foundry Society
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• v.12 no.3
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• pp.220-229
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• 1992

The degree of purification and the macrostructure of high purity aluminium were studied through the alternate stirring method in order to improve the nonuniformity of solute concentration in the unidirectional stirring method. The $2^3$ factorial design was done to examine the effects of experimental factors more qualitatively. In the relatively low stirring speed of 1500 rpm with alternate stirring mode, the uniform solute profile and refined grain structure were obtained due to strong washing effect and turbulent fluid flow. It was induced by the transition of the momentum boundary layer by alternation of the stirrer. It was concluded from this study that the alternate stirring mode was more effective to obtain the uniformity of solute even in the stirring speed of 1500 rpm. But the degree of purification decreased below the critical alternating period. When 2N(99.8wt.%) aluminium was used as the starting material the morphology of solid-liquid showed the cellular shape and the columnar grains were inclined to the direction of rotation. This inclined grain growth resulted from the difference of relative velocities of solid and liquid. The inclined angle was increased as the stirring speed increased and solidification proceeded. In the case of 4N aluminium, there was no inclined grain growth and it was confirmed from the macrostructure and SEM work that the morphology of solid-liquid interface was planar. From the factorial design, it was found that the alternate stirring mode showed poorer purification effect than that of unidirectional stirring mode at low speed(500 rpm). In addition, the factor that had the most significant effect on the degree of purification was the stirring speed.

• Resources Recycling
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• v.11 no.5
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• pp.21-23
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• 2002

A new process based on the co-precipitation method was developed fer removing harmful impurities during Mn-Zn ferrite production such as $SiO_2$ and P from waste pickle liquor. By this process a final result of less than 100 ppm of $SiO_2$ and less than 10 ppm of P content in the ferric oxide is easily attained. Though Ca cannot be removed by this process, water rinsing of the ferric oxide is effective fer reducing Ca content to less than 100 pm. For further purification, the origins of each impurity must be investigated and then taken away.

• Journal of the Korean Ceramic Society
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• v.25 no.6
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• pp.655-664
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• 1988

As a part of study to establish the industrial process for manufacturing high purity alumina powder which is largely used as fine ceramics, an adsorption method using a silica-containing material which can absorb to eliminate a major impurity, Na in aluminum hydroxide as a raw material has been studied. It is confirmed that the primary property of powder such as the particle size of raw material and that of silica-containing material plays a great important role in the purification process.

• Analytical Science and Technology
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• v.24 no.6
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• pp.477-483
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• 2011

This work is on the synthesis of EMI-$BF_4$ (1-ethyl-3-methylimidazolium tetrafluoroborate) and purification of spectroscopic grade using aluminium oxide method, activated charcoal method, and liquid/liquid fractional extraction method in order to make supercapacitor finally. But the aluminum oxide method and the activated charcoal method were not suitable for obtaining high-purity ionic liquids. The liquid/liquid fractional distillation method turned out that as the concentration of solvent ($H_2O$) was increased, the higher purity of EMI-$BF_4$ was obtained and the electrical capacity of this compound was increased to higher value. When the solvent was changed to from methylene chloride to 1,2-dichloroethane, the higher purity of EMI-$BF_4$ was obtained.