• Resources Recycling
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• v.10 no.5
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• pp.22-28
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• 2001

Recovery of silver in the spent solution generated from MEO(Mediated Electrochemical Oxidation) process, which is a process to decompose radioactive organic mixed wastes at low temperature, was performed using chemical method. Silver nitrate in 5M nitric acid solution could be completely recovered as AgCl by using 1% excess of the stoichiometric HCl equivalents. Then, AgCl was transformed to Ag metal by reduction reaction with hydrogen peroxide under alkaline media. The optimum pH for the reduction to silver metal was found to be in the range of 12.8∼13.0.

• KSBB Journal
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• v.21 no.3
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• pp.199-203
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• 2006

Precipitation and reactive distillation were employed to recover lactic acid from fermentation broth. Lime was initially added to fermentation broth in order to convert soluble lactic acid to an insoluble calcium lactate form. Drowning-out crystallization was used to decrease the solubility of calcium lactate by adding ethanol as a co-precipitant. In the ideal solution of organic acids as well as fermentation broth, precipitation experiments were performed with varying amounts of ethanol. Precipitation process was followed by reactive distillation. Carboxylate salts formed in the previous precipitation process were mixed with carbon dioxide and triethylamine to precipitate as calcium carbonate. The remaining liquid was distilled for 1 hr at different temperatures. Triethylamine and water were recovered from the top of the distiller, while organic acids, inducing lactic acid as a main component remained in feeding bottle. The yield of recovered lactic acid was 67.5% with the purity of 99.7%.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.195-200
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• 1997

핵융합로 증식재용 r-LiAlO$_2$, Li$_2$ZrO$_3$, Li$_2$TiO$_3$ 분말을 자발착화 연소반응법으로 합성하였다. LiAlO$_2$와 달리 Li$_2$ZrO$_3$ 와 Li$_2$TiO$_3$는 가열하는 동안 침전물이 생겼지만 카르복실산기만을 지닌 구연산과 아민기만을 지닌 우레아를 화학정량의 조성으로 혼합한 연료로 쉽게 분말을 합성할 수 있었다. LiAlO$_2$나 Li$_2$TiO$_3$분말은 별도의 하소 공정이필요없이 원하는 결정상이 형성되었으며, Li$_2$ZrO$_3$분말은 Li이 과량인 상이 형성되므로 110$0^{\circ}C$에서 하소하여 원하는 상을 얻었다. 합성된 Li계 산화물 분말은 비표면적 10~17 $m^2$/g으로 약 150 nm정도의 입자크기를 갖는 미세한 입자이었다.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.04a
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• pp.24-25
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• 1994

한식간장은 콩을 주원료로 하여 콩속의 성분을 수용성단백질 및 아미노산으로 변화시켜만든 조미료로서, 콩으로 메주를 만든다음 20일 동안 배양해서 만든 종국(Seed)과 혼합후 발효시킴으로써 제조되며 발효공정을 통해 Total Nitrogen이 증가되게 된다. 이러한 한식간장은 탈지대두를 사용하는 양조간장과는 달리 메주를 쑤어서 만들기 때문에 탈지가 되지 않은 제조과정으로 인하여 여과 및 공정중 발생하는 잡물질의 제거가 어렵게 된다. 제조공정중 여과공정을 거치게 되는데 여과포를 사용한 압착공정으로 이루어지며 여과된 간장에는 발효에 사용된 균$\cdot$효모등이 $10^7$개/ml 수준으로 존재하여 저장안정성 및 품질보전을 위해 열처리 과정을 거치게 된다. 이 열처리가 끝난 간장은 방치$\cdot$냉각시켜 첨가제를 혼합한 후 포장된다. 냉각과정중 2차 침전물이 생성되기도 하며 멸균이 확실치 않거나 2차 오염등으로 인한 발효로 인해 $CO_2$ Gas가 발생하기도 하여 품질이 나빠지는 원인이 된다. 이러한 열살균방식은 에너지를 많이 소비하고 열살균시 간장성분으로 인한 Scale 형성등 문제점을 안고 있다. 또한 열살균을 통해 살균은 할 수 있지만 사균, 분해물질, 간장에 함유된 고약한 냄새를 풍기는 잡성분의 제거는 불가능하다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.4
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• pp.143-149
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• 2020

Calcium phosphates recognized as important bio-materials have been successfully synthesized by simple precipitation using waste abalone shells, which are rich mineral sources of calcium. Calcium hydroxide (Ca(OH)₂) originated from abalone shells was used as calcium source (precursor) for the preparation. Synthesis of calcium phosphates was performed by reacting calcium hydroxide with phosphoric acid (H₃PO₄) in aqueous solution. The initial precursor Ca/P ratios were adjusted to 1.50, 1.59 and 1.67, and the effect of the composition and the heat treatment on the synthesized powders and sintered bodies was investigated. The phases of the sintered ceramics prepared at 1150℃ were hydroxyapatite (HAp), β-tricalcium phosphate (β-TCP), and biphasic phosphate (HAp with β-TCP)), which were determined by the initial precursor Ca/P ratios. The results demonstrate the possibility for the synthesis of high value-added calcium phosphates from economical starting materials with low cost and high availability.

• Applied Biological Chemistry
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• v.26 no.4
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• pp.199-204
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• 1983

As a way of utilizing cheese whey to fortify sulfur-bearing amino acids to soybean protein, whey-soybean coagulum was made from whey-soy milk mixture and optimum conditions for coprecipitation of the two proteins were determined. Mixture of whey and soymilk in 1 : 1 volume ratio was coagulated at $0.005{\sim}0.5M$ of $CaCl_2$ concentration, pH $1.5{\sim}8.0$, and at $60{\sim}100^{\circ}C$, and absorbance at 500nm of filtrate from the coagulum was measured. Optimum conditions for the coprecipitation were 0.0125M of $CaCl_2$ concentration, pH $6.5\sim7.5$, and $70{\sim}80^{\circ}C$ which resulted in the minimum absorbance and also good physical properties of the curd.

• Resources Recycling
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• v.17 no.1
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• pp.38-42
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• 2008

This study was carried out to investigate the solubility of vanadium in ammoniacal solution and precipitation of $NH_4VO_3$ as a function of temperature and addition of ammonia salt. Higher solution temperature is required to get high solubility of vanadium and the vanadium concentration of solution was 16.8g/L at $90^{\circ}C$ with the solution of 20 g/L $(NH_4)_2CO_3$ and 2.5M $NH_4OH$. From this solution, vanadium could be precipitated up to 99.8% with adding 20 g/L $NH_4Cl$, 72 hours settling time at $25^{\circ}C$.

• The Journal of Engineering Geology
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• v.14 no.3 s.40
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• pp.301-311
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• 2004

This study is suggested a new dielectric tracer test method to understand geological structure of porous media and groundwater flow to use the dielectric constant which is one of electrical special quality of various geological materials. To measure their parameters, tracer material is made an ethanol mixing liquid(EML) having a same specific gravity of water. Also, soil materials are prepared a dielectric tracer test using the FDR system that could measure dielectric constant for saturated standard sand and river sand layers which have different initial porosity. To compare with their results, we discussed with the concentration variation of saline water having a saline concentration $3\%$ which is general tracer material by using the electro multi-meter system in the laboratory or field test. In two tracer experiment results, EML tracer test could confirm definitely EML concentration variation from each saturated soil layer as standard and river sands. However, tracer test of saline water $3\%$ concentration could not confirm permeating movement of water by degree of salinity change because these are settled at lower part column in a whole column area continuously. These causes are that specific gravity of saline water is heavier than water. That is, it could know that deposition of saline water is composed of lower part of soil column continuously independently of the direction of water into saturated soil material.

• Korean Journal of Materials Research
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• v.4 no.4
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• pp.472-476
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• 1994

Phase transformation of PbO-precursor prepared from $Pb(NO_{3})_{2}$ by precipitation technique was observed by TG-DTA, XRD, FT-IR, and Raman spectral analysis. PbO-precursor was derived from an aqueous solution of $Pb(NO_{3})_{2}$ at $45^{\circ}C$ and pH of 9.0. The precipitate showed it to be the mixture of hydrous lead oxynitrate and lead hydroxynitrate. With increasing heat-treatment temperature ranging up to $560^{\circ}C$, the precursor changed to $3Pb(NO_{3})_{2}$ . 7Pb0, $Pb(NO_{3})_{2}$. 5Pb0 and PbO(litharge), in turn. Finally, it transformed to massicot form of PbO above $560^{\circ}C$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.1
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• pp.27-32
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• 2006

We separated semiconducting single-walled carbon nanotubes(sem-SWCNT) from the HiPco-SWCNTS by dispersion with octadecylamine(ODA). The mixture of acid-treated SWCWTS and ODA was heated at $120^{\circ}C$ for 120hours. ODA physisorbs selectively on the side-wall of sem-SWCNTS. The ODA-treated CNTs were dispersed in tetrahydrofuran(THF) via sonication. The ODA-physisorbed sem-SWCNT can be retained in the supernatant of THF, but met-SWCNT and unabsorbed sem-SWCNT were precipitated in THF. Raman spectra with 514 nm and 1074 nm were investigated. The amount of sem-SWCNT in the supernatant and precipitant was about 94 % and 50 %, respectively.