• Resources Recycling
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• v.3 no.1
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• pp.9-16
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• 1994

Fine cobalt metal powders was produced from domestic Stellite scrap by decomposing it with molten sodium hydroxide. Complete decomposition of the scrap could be obtained with the weigth ratio of sodium hydroxide to Stellite being about 2 at the temperature ranges of $750~800^{\circ}C$ for an hour. The cobalt-bearing compound was identified as $Co_2O_3{\dot}H_2O$ by X-ray analysis and D.T.-T.G.a.. The compound was then digested in HCI to form cobalt chloride, and after iron removal by adjusting the pH of the solution, cobaltous or cobaltic hydroxide was precipitated at the pH of about 13 or 4, respectively. The precipitates were reduced by hydrogen in the temperatures of $400~500^{\circ}C$ to fine cobalt powders of high purity with the size of 1.0 to $1.5\mu\textrm{m}$. The recovery of cobalt from Stellite scrap was about 75~86% by weight.

• Journal of Environmental Science International
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• v.9 no.5
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• pp.437-441
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• 2000

A study on the removal of Pb ion from Pb-contaminated soil was carried out using ex-site extraction process. Tartaric acid (TA) and iminodiacetic acid sodium salt(IDA) as a washing agent were evaluated as a function of concentration reaction time mixing ratio of washing agent and recycling of washing agent. TA showed a better extraction performance than IDA. The optimum washing condition of TA and IDA were in the ratio of 1:15 and 1:20 between soil and acid solution during 1 hr reaction. The total concentrations of Pb ion by TA and IDA at three repeated extraction were 368.8 ppm and 267.5 ppm respectively. The recovery of Pb ion from washing solution was achieved by adding calcium hydroxide and sodium sulfide form the precipitation of lead hydroxide and lead sulfide and optimum amounts of sodium sulfide and calcium hydroxide were 7 g/$\ell$ for the TA washing solution and 4 g/$\ell$, 5g/$\ell$ for the IDA washing solution respectively. The efficiency of recycle for TA and IDA washing solution were 78.8% , 95.1%, and 89.2%, 96.6% at third extractions under $Na_2S$ and $Ca(OH)_2$, respectively.

• Journal of the Korea Furniture Society
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• v.19 no.5
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• pp.358-364
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• 2008

Wood-inorganic material composite (WIC) was prepared by impregnating wood with copper sulfate ($CuSO_4\;5H_2O$) solution and by immersed wood in sodium carbonate($Na_2CO_3$) solution in order to introduce insoluble copper compounds {copper carbonate hydroxide, $CuCO_3\;Cu(OH)_2$} into the wood to give fungicidal effects in treated-wood. The weight percent gains (WPGs) of treated wood reached maximum value by impregnation of 20% copper sulfate solution and immersion in about 15% sodium carbonate solution for 24 hrs. Inorganic substances were present mainly in the lumina and cross-field pitting of tracheides. These substances were proved to be the insoluble copper carbonate hydroxide against water by the energy dispersive X-ray analyzer in conjunction with a scanning electron microscope (SEM-EDXA). The treated specimens showed high preservative effectiveness because the weight losses were hardly occurred by the fungi degradation test.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.98.1-98.1
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• 2017

본 연구에서는 정전류 조건에서 알루미늄 합금의 PEO(Plasma Electrolytic Oxidation) 피막 형성 거동에 대한 전해질 조성의 영향을 아크 발생 양상, 전압-시간 곡선 및 형성된 표면피막의 구조를 관찰하여 연구하였다. 실험에 사용된 전해질은 NaOH 수용액에 $Na_2SiO_3$을 혼합하여 구성되었으며, NaOH와 $Na_2SiO_3$의 농도는 각각 0.01 ~ 1.0 M 와 0 ~ 2.0 M 사이로 조절되었다. 0.01 M NaOH 이하의 용액에서는 양극전압이 500 V 이상으로 상승되고 미세한 아크가 시편 표면 전체에 발생했으나, 0.02 M NaOH 이상의 농도에서는 양극전압이 300 V 이하로 감소되었고 아크발생이 관찰되지 않았다. 아크발생이 일어나지 않는 고농도의 0.5 M NaOH 용액의 경우 0.1 M 이상의 $Na_2SiO_3$를 첨가하였을 때 작은 아크의 무리가 발생되었다. 0.5 M NaOH 수용액에 0.1 M ~ 0.2 M $Na_2SiO_3$가 첨가되었을 땐 아크 무리가 발생하나 이내 일부 영역에서만 반복적으로 아크가 발생하는 로컬 버닝 현상이 일어났다. 한편 0.5 M NaOH 수용액에 0.5 M 이상의 $Na_2SiO_3$가 첨가되었을 때는 로컬 버닝이 일어나지 않고 전 표면에 걸쳐서 아크 무리가 이동하며 PEO 피막이 형성되었다. 0.01 M NaOH 수용액에서 형성된 PEO 피막의 두께는 처리 시간에 따라 증가하지 않고 $10{\mu}m$ 이하의 낮은 값을 보였다. 반면에 NaOH와 $Na_2SiO_3$ 혼합수용액에서 형성된 피막의 두께는 약 $30{\mu}m$ 이상의 높은 값을 보였다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.2
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• pp.101-107
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• 2013

Cerium compounds such as Cerium hydroxide ($Ce(OH)_3$), Cerium chloride ($CeCl_3{\cdot}nH_2O$), Cerium carbonate hydrate ($Ce_2(CO_3)_3{\cdot}8H_2O$), Cerium oxide ($CeO_2$) were synthesized using recycled Ce precursor. Cerium(IV) oxide of nanoparticles were obtained by Ultra-sonication. Cerium-sodium- sulfate compound was synthesized through acid-leaching and addition of sodium sulfate from 99 wt% purity of Ce precursor as a starting material that was recycled from the waste polishing slurry. Moreover Cerium hydroxide was obtained from Cerium-sodium-sulfate compound by adding to sodium hydroxide solution. Then Cerium chloride was synthesized by adding of hydrochloric acid to Cerium hydroxide. Needle-shaped Cerium carbonate hydrate was synthesized in the continuous process and Cerium(IV) oxide with 30~40 nm size was subsequently obtained by the calcinations and dispersion.

• Journal of the Korean Society of Clothing and Textiles
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• v.11 no.2 s.24
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• pp.101-112
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• 1987

The purpose of this study is to investigate the influence of addition of sodium dodecyl sulfate(SDS) when wool is treated with sodium hydroxide(NaOH). Physical and chemical changes were examined on wool treated with various cone. of NaOH and SDS simultaneously. The result are as follows. 1. The higher the temperature and the longer the time of NaOH treatment are, the more alkali damage wool get : increase in weight loss and decrease in urea-bisalphite solubility and in tensile strength. But the treatment time reacts less effective than the temperature. 2. When wool is treated with NaOH, at NaOH cone. under $10^{-3}M$., the addition of SDS alleviates the alkali reaction on wool: increase in cystine contents and in urea-bisulpite solubility, and decrease in degree of swelling. On the other hand, at NaOH cone. over $10^{-2}M$., the addition of SDS promotes the alkali reaction on the wool. 3. When wool is treated with NaOH, the addition of SDS shows no changes on the tensile strength. On the other hand, at NaOH cone. under $10^{-2}M$., the addition of SDS shows no changes on the softness of wool, but at the $10^{-1}M$. NaOH cone. addition of SDS increases the soft-ness of wool. The area shrinkage of wool treated with NaOH and SDS shows less changes than with NaOH only.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.151.2-151.2
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• 2017

본 연구에서는 정전류 조건에서 알루미늄 합금의 PEO(Plasma Electrolytic Oxidation) 피막 형성 거동에 미치는 전해질 내 cation($K^+$, $Na^+$)의 영향을 아크 발생 양상, 전압-시간 곡선 및 형성된 표면피막 구조를 관찰하여 연구하였다. 전해질은 0.5 M NaOH + 1 M $Na_2SiO_3$ 수용액과 0.5 M KOH + 1 M $Na_2SiO_3$ 수용액이 사용되었다. 아크 발생은 cation의 종류에 상관없이 동일하게 가장자리부터 시작되어 내부로 이동함으로써 전 표면에 걸쳐서 일어났다. 전 표면에서 PEO 피막이 형성된 이후에는 한 지점에서 지속적으로 아크가 발생하는 로컬버닝 현상이 두 용액에서 모두 관찰되었으나 $K^+$이온이 포함된 용액에서 로컬버닝이 빠르게 일어났다. 시편표면에서 아크가 발생하는 동안 중 각 전해액에서의 전압-시간 곡선에서 전압의 상승과 하강이 반복되는 거동이 동일하게 관찰되었다. 이러한 전압 등락의 크기는 $K^+$ 이온이 포함된 수용액에서 더 크게 나타났으며, 그 결과 표면 거칠기가 상대적으로 더 높은 PEO 피막이 형성되었다.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.6
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• pp.518-523
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• 2013

This paper describes the reduction of a hydrogen sulfide ($H_2S$) generated from a biogas plant. Micro bubble system is adopted to supply air into the water in the reaction chamber, which can increase the contact area of the supplied air to the reserving water. Two stage reaction chambers having two reaction rooms are designed and manufactured to enhance the reduction rate of a hydrogen sulfide. Sodium hydroxide (NaOH) is also considered to get rid of a hydrogen sulfide. Air volume rate to the water in a reaction chamber is maintained between 0.5 and $1.0m^3/min$. Throughout experimental measurement of the concentration of a hydrogen sulfide by changing the volume of supplied air into the water, reduction rate of a hydrogen sulfide increases as air volume increases. Adding sodium hydroxide to the water with the air supply can reduce effectively a hydrogen sulfide up to 99.5% from biogas. It is noted that a hydrogen sulfide generated by a biogas plant can reduce by supplying micro bubble air and sodium hydroxide effectively.

• Textile Coloration and Finishing
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• v.15 no.4
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• pp.73-79
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• 2003

It is generally known that cotton treated with liquid ammonia has better soft handle, wrinkle recoveries and stability of appearance as compared with the alkali mercerized cotton. In this study, the various cotton fabrics treated with liquid ammonia$(NH_3)$, sodium hydroxide(NaOH) and sodium hydroxide(NaOH)/liquid ammonia$(NH_3)$ and untreated cotton fabric were investigated and compared in terms of physical properties and dyeing behavior. As the result, the strength of four kinds of cotton fabrics were similar. But the elongation of cotton treated with liquid ammonia increased slightly. Liquid ammonia treatment reduced the crystallinity of cotton and the crystalline structure of cotton transformed from cellulose 1 to mixed structure of celluloseIand III. In dyeing, dyeing rate decreased but equilibrium dye uptake increased by liquid ammonia treatment of cotton fabrics.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.3
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• pp.109-116
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• 2012

This study investigated the effects of blast furnace slag mortars activated with sodium hydroxide(NaOH) and gypsum in relation to flow, setting time and compressive strength. The parameters in this studied was the gypsum ratio 0 to 50%, 3M and 6M of activator concentration and $20{\pm}2^{\circ}C$ and $35{\pm}2^{\circ}C$ of curing temperatures. The results of flow was increase, setting time was increase as the amount of gypsum increases. But the results of compressive strength was dependent on the gypsum ratio, indicating that the compressive strength increased with the increase of the amount of gypsum until a certain limit, beyond which the strength decreased quickly.