• 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 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.

• Korean Journal of Materials Research
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• v.26 no.6
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• pp.306-310
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• 2016

To produce 4N grade high-purity silica powder from natural ore, the mineralogical characteristics of natural silica ore were investigated and their effects on the purification process were revealed. The Chinese silica mineral ore used was composed of iron and aluminum as main impurities and calcium, magnesium, potassium, sodium, and titanium as trace impurities; these trace impurities generally exist as either single oxides or complex oxides. It was confirmed that liberation and acidic washing of the impurities were highly dependent on the particle size of the ground silica ore and on its mineralogical characteristics such as the distribution and phases of existing impurities. It is suggested that appropriate size reduction of silica ore should be realized for optimized purification according to the origin of the natural silica ore. A single step purification process, the mechano-chemical washing (MCW) process, was proposed and verified in comparison with the conventional multi step washing process.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1995.04a
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• pp.18-18
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• 1995

• Carbon letters
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• v.11 no.3
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• pp.184-191
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• 2010

Carbon nanotubes are unique tubular structures of nanometer diameter and large length/diameter ratio. The nanotubes may consist of one up to tens and hundreds of concentric shells of carbons with adjacent shells separation of ~0.34 nm. Multiwalled carbon nanotubes were synthesized by arc-discharge technique. MWCNTs were formed at the cathode deposit along with other carbonaceous materials like amorphous carbon, graphite etc. However, to get the best advantage of carbon nanotubes in various advanced applications, these undesired carbonaceous materials to be removed which is a challenging task. In the present study, various techniques were tried out for purifying MWCNTs such as physical filtration, chemical treatment and thermal annealing. SEM, FTIR, TGA and BET techniques were used to characterize the CNTs at various stages. Results shows that suitable chemical treatment followed by thermal annealing under controlled flow of oxygen gives the better route for purification of carbon nanotubes.

• Korean Journal of Rural Living Science
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• v.10 no.2
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• pp.78-84
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• 1999

This study was performed to find out the usefulness of chestnut powder recovered from the inner layer, which used to be discarded. After the Physicochemical properties of the chestnut powder were examined, breads were prepared with 10-50% of chestnut Powder and the sensory quality was compared by QDA. Bread could be made even using up to 50% of chestnut powder, and in 20-30% of chestnut powder, the sensory quality was acceptable enough compared with wheat bread. Even though the low purity of the chestnut powder affected the flavor and color, the breads contained it were generally acceptable. Therefore, the chestnut powder recovered from the inner layer can be used as the effective food resource as itself, and with the higher purification to remove inner layer, it can be applied to more diverse food.

• Resources Recycling
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• v.13 no.1
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• pp.22-27
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• 2004

Purification on the leaching solution of the crude zinc oxide obtained by the reduction of EAF dust has been carried out. Pb and Cd ions in the leaching solution were precipitated and removed from the solution by the addition of zinc metal powder. The purification condition for electrowinning to obtain the high purity zinc metal was investigated by analyzing the effects of Pb and Cd ion concentrations on the contents of impurities in the recovered zinc metal. The 3 N purity zinc metal was obtained at the electrolysis condition of the concentrations of Pb less than 2 ppm and Cd less than 0.1 ppm in the purified solution. For this purification, the amounts of zinc metal powder more than 8.5 g/l should be added in the crude zinc oxide leached solution.

• Resources Recycling
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• v.31 no.5
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• pp.52-58
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• 2022

Silicon carbide powder was prepared from carbon black and silicon recovered from waste solar panels. In the solar power generation market, the number of crystalline silicon modules exceeds 90%. As the expiration date of a photovoltaic module arrives, the development of technology for recovering and utilizing silicon is very important from an environmental and economic point of view. In this study, silicon was recovered as silicon carbide from waste solar panels: 99.99% silicon powder was recovered through purification from a 95.74% purity waste silicon wafer. To examine the synthesis characteristics of SiC powder, purified 99.99% silicon powder and carbon powder were mixed and heat-treated (1,300, 1,400 and 1,500 ℃) in an Ar atmosphere. The characteristics of silicon and silicon carbide powders were analyzed using particle size distribution analyzer, XRD, SEM, ICP, FT-IR, and Raman analysis.

• Korean Journal of Food Science and Technology
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• v.48 no.6
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• pp.542-547
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• 2016

The thermal properties of ramie leaf ${\beta}$-amylase (RBA) were examined to develop a novel process for enzyme purification. The thermostability of RBA extract prepared from ramie leaf powder was examined at various temperatures. RBA activity decreased slightly, whereas other carbohydrate-active enzymes, such as $\small{D}$-enzyme, were rapidly inactivated during 30 min incubation at $60^{\circ}C$. When the heat-treated extract was incubated with various substrates, maltose was produced exclusively as the major product, whereas the untreated crude extract produced maltose and other maltooligosaccharides. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, fewer protein bands were observed for the heat-treated extract than the untreated extract, indicating that the thermostable RBA was partially purified and other thermolabile enzymes were eliminated. Thus, the treatment of the RBA extract at $60^{\circ}C$ for 30 min resulted in 5.4-fold purification with a recovery yield of 90%.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.510-513
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• 2002

Iron is an essential nutrient for most organisms, which supplied to them in a protein-iron complex known as ferritin. Ferritins are multimeric proteins those are consisted of spherical shell of 24 subunits defining a cavity of about 8nm in diameter. Soluble form of ferritin was separated from disrupted cells, followed by silica powder adsorption. Ferritin was recovered from silica-poweder by distiiled water, which was applied to DEAE anion exchage chromatography. Collected fractions from the DEAE column were assayed to gain the amount and the purity of ferritin by using GF-HPLC.