• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.133-139
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• 2000

In this study, activated carbon was prepared from solid residue after lignin pyrolysis by using zinc chloride as an activation agent. The steam activation method was adopted to manufacture activated carbon from solid residue after lignin pyrolysis. The effect of process operation variables such as activation temperature, activation time and mass of activation agent added to char on the pore structure and specific surface area of the activated carbon was investigated. Activated carbon with high surface area and well-developed pore structure could be prepared, when solid residue after lignin pyrolysis was mixed with zinc chloride of 300 wt% and then the mixture was activated for 1 hour at $1000^{\circ}C$ in a stream of nitrogen.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1292-1295
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• 2006

Three kinds of electrolyte membranes were prepared by impregnating filter papers with one of the electrolyte solutions fur primary manganese battery ($NH_4Cl$, $ZnCl_2$, and alkaline types) and hygroscopic agent ($CaBr_2$ or $CaCl_2$), respectively. The thickness of them was $250{\sim}300{\mu}m$, and they were very flexible. The electrochemical characteristics greatly depended on the hygroscopic agent to supply water to the cell. The electrolyte membrane containing $CaCl_2$ showed the highest ionic conductivity and the largest discharge capacity.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.3
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• pp.456-464
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• 1997

The effect of the additives on the Zn-Ni alloy electrocrystallization from a chloride bath was investigated by means of electrochemical methodes, scanning electron microscopy and measurement of surface appearance, X-ray diffraction patterns. The additives tested were the surfactant of naphtalene-derivative, saccharin and aliphatic alcohol. The resistance of electrodeposit increased by adding the additives, whereas the effect of additives on resistance was different with current density. The nickel content of alloy deposit was increased by the addition of alcohol, while decreased by the surfactant. The surface roughness, appearance and morphology of deposit were also influenced by the type of additive. The fine, compact grains and good surface roughness could be obtained from the surfactant or alcohol -added bath, and the surfactant or saccharin improved the surface appearance.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.3
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• pp.169-175
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• 1976

A solvent extraction-atomic absorption spectrophotometry for determination of trace amount of cadmium, copper, lead and zinc and a flameless atomic absorption spectrophotometry for mercury in sea water were studied. The optimum pH range for solvent extraction was pH 4-7. A better solvent extraction efficiency was obtained with MIBK solvent than nitrobenzene, benzene, isoamylalcohol, n-buthylacetate. DDTC was more advantageous than APDC as chelating agent. The metals, chelated with DDTC and concentrated into MIBK by solvent extraction with a volume of $1\iota$ of sea water for cadmium, copper and lead, and 200m1 for zinc, were determined simultaneously by atomic absorption spectrophotometry. For mercury determination, 500ml of sea water was digested with permanganate-sulfuric acid and mercury( II ) was reduced by stannous chloride and aerated the solution with air pump until the absorbance reached a constant value. The precisions, in standard deviation, of these methods were 0.058ppb for cadmium, 0.084 ppb for copper, 0.44ppb for lead, 2.49ppb for zinc and 0.08 ppb for mercury. The sensitivities, expressed in $ppb/1\%$ absorption, were 0.058 ppb cadmium, 0. 15 ppb copper, 0.6 ppb lead, 1.2 ppb zinc and 0.01 ppb mercury respectively. No significant adsorption on the wall of polyethylene sample bottle occurred during 30 days of storing by acidification to pH 1.5 with nitric acid except zinc. Poor reproducibility was found for zinc with this method.

• Journal of Surface Science and Engineering
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• v.29 no.4
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• pp.219-228
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• 1996

Neutral Zinc Electroplating(NZE) utilizing the electrolyte of pH 6 to 8 has advantages in waste treatment and the protection of equipment. NZE is beneficially used in chromating treatment, but the limiting current density and the current efficiency are low. Therefore this study is investigated to analyse the characteristics of NZE and to obtain high current density and current efficiency. The deposition potential of zinc in the NZE bath is about 110mV, which is lower than acidic bath. The current density possibily increases up to 60A/d$\m^2$ in lower complexing agent content and pH 6. More than 90% of cathodic current efficiency was obtained in NZE bath. The NZE morphology shows smaller grains than acidic bath. The addition of 4$m\ell$/1 second brightener gives finer morphology. As pH becomes higher, (002) plan decreases and (100), (101) and (110) planes increase in the no additives solution.

• Economic and Environmental Geology
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• v.26 no.3
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• pp.421-429
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• 1993

Dissolution reactions of chemical grade zinc sulfide and natural sphalerite were studied in ferric chloride solution as an oxidant. To enhance the leaching reaction, ultrasonic technique was employed in this investigation. For the reaction with pure zinc sulfide, chemical reaction was the rate limiting step in the range of low conversion irrespective of applying ultrasonic wave. And the diffusion through liquid film instead of diffusion through product layer of free sulfur was the rate determining step because ultrasonic vibration removes the product from reaction zone. In the case of sphalerite with the ultrasonic vibrator, it was found that inert mineral layer diffusion was the rate determining step, in which the elemental sulfurs formed were removed by the ultrasonic action. Experimental results showed that the ultrasonic technique proved to be the methods which can significants improve the leaching performance.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.130-130
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• 2003

현재, 메탈의 내부식성 코팅막 제조에 사용되고 있는 크로메이트 기반 코팅제는 유독성 물질에 대한 환경 규제에 따라 조만간 사용이 금지 될 예정이다. 본 연구에서는 이러한 유독성 금속 내부식성 코팅제를 대체할 새로운 환경 친화적인 코팅 재료로서 A1OOH 나노졸이 분산된 ZrOCl$_2$ㆍ8$H_2O$-GPS(3-Glycidoxypropyltrimethoxysilane)하이브리드 졸을 제조하고 이의 내 부식성 특성에 대하여 조사하였다. AlOOH 졸이 첨가된 유/무기 하이브리드 졸은 염화 알루미늄을 염기로 침전 시킨 수산화 알루미늄 침전물에ZrOCl$_2$ㆍ8$H_2O$를 10 ~ 20 wt% 첨가하고 열처리한 후 여기에 GPS를 AlOOH에 대하여 4 ~ 6몰 배 첨가하여 제조하였다. 제조된 하이브리드 형 졸은 가시관 투광성이 우수하며 시간에 따른 범도 변화가 거의 없었다. 이 코팅 졸을 아연 도금 강판에 딥 코팅법으로 코팅한 후, 상온~20$0^{\circ}C$에서 열처리하여 염수 시험법으로 하이브리드 졸의 조성 및 열처리 조건에 따른 코팅막의 내부식성 특성을 조사하였다. 또한, 코팅막의 두께를 전자 현미경으로 관찰하였고, 코팅막 경도는 연필 경도계로 조사하였다.

• Journal of Surface Science and Engineering
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• v.33 no.5
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• pp.339-348
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• 2000

The study was conducted on the effect of bath composition on the surface appearance, the hardness and the crystal orientation of zinc electrodeposits from the chloride bath. (1) The hardness of the zinc electrodeposits from the chloride bath was increased by suppressing mass transfer of zinc through adding the organic additives and the chlorine ion in the electrolyte. (2) The surface whiteness of zinc deposits was decreased due to the change of the preferred orientation from (002) , (103) to (101) , (100) through increasing the organic additives and chlorine ion in the electrolyte. (3) The addition of Cu, Sn, Ni or Co in the chloride bath elevated the hardness of the zinc deposits but darkened the surface whiteness. (4) The optimum condition of the organic additives and the chlorine ion for increasing the hardness of zinc deposits and preventing dark surface ranges 0.3 m1/1 to 0.4 m1/1 and 6.5 mol/1 to 6.8mol/l respectively.

• Clean Technology
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• v.25 no.1
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• pp.14-18
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• 2019

In general after the etching process, waste etching solution contains metals. (ex. Nickel (Ni), Chromium (Cr), Zinc (Zn), etc.) In this work, we proposed a recycling process for waste etching solution and refining from waste liquid contained nickel to make nickel metal nano powder. At first, the neutralization agent was experimentally selected through the hydrolysis of impurities such as iron by adjusting the pH. We selected sodium hydroxide solution as a neutralizing agent, and removed impurities such as iron by pH = 4. And then, metal ions (ex. Manganese (Mn) and Zinc (Zn), etc.) remain as impurities were refined by D2EHPA (Di-(2-ethylhexyl) phosphoric acid). The nickel powders were synthesized by liquid phase reduction method with hydrazine ($N_2H_4$) and sodium hydroxide (NaOH). The resulting nickel chloride solution and nickel metal powder has high purity ( > 99%). The purity of nickel chloride solution and nickel nano powders were measured by EDTA (ethylenediaminetetraacetic) titration method with ICP-OES (inductively coupled plasma optical emission spectrometer). FE-SEM (field emission scanning electron microscopy) was used to investigate the morphology, particle size and crystal structure of the nickel metal nano powder. The structural properties of the nickel nano powder were characterized by XRD (X-ray diffraction) and TEM (transmission electron microscopy).

• YAKHAK HOEJI
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• v.44 no.1
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• pp.1-8
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• 2000

Effects of Astragali radix extract (AG) on the humoral immunotoxic responses of zinc chloride (Zn) were studied in ICR mice. Mice were divided into 4 groups (10 mice/group), and Zn was given to the mice, 1 hr after i.p. injection with 0.5 g/kg of AG, by i.p. injection daily for 10 days at a dose of 25 mg/kg. Mice were immunized and challenged with sheep red blood cells (SRBC). Zn treatment increased the relative weight of spleen compared with those in controls, but decreased the hemagglutination (HA) titer 2-mercaptoethanol-resistant HA (MER-HA) titer and splenic plaque forming cells (PFC). AG treatment significantly increased the relative weight of spleen, HA titer and PFC compared with those in controls. Combination of Zn and AG significantly increased the relative weight of spleen compared with those in controls, but decreased the HA titer, MER-HA titer and PFC. The relative weight of spleen was significantly increased in the Zn and AG combination group than those in Zn alone treatment group. But the HA titer, MER-HA titer and PFC were slightly increased in the group of combination. These results suggest that AG might slightly restore humoral immune responses lowered by an excess of zinc.