• Applied Biological Chemistry
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• v.28 no.2
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• pp.68-75
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• 1985

Laboratory experiments were conducted to investigate the effect of compost and humic acid treatment on adsorption of Cd, Zn, and Cu in soils. Three soils differing in physical and chemical properties used in this experiments were Bonyrang (Typic Udifluvents) SL, Gangseo (Aquatic Eutrochrepts) L, and Gyorae (Typic Distrandepts) SiL. Adsorption of Cd, Zn, ana Cu on the soils followed Langmuir isotherm up to 75 ppm of initial concentration. The adsorption maxima of Cd, Zn, and Cu for the Bonryang soil, the lowest in pH, organic matter content, and CEC, were the lowest of the three soils. Although the Gyorae soil derived from volcanic ash was the highest in organic matter content and CEC, the adsorption maxima of heavy metals for the Gyorae soil were lower than those for the Gangseo soil of which organic content and CEC were intermidiate. The adsorption maxima/CEC ratios for the Bonryang, the Gangseo, the Gyorae soils were found to be in the range of $23{\sim}27%,\;28{\sim}57%$, and $11{\sim}14%$ respectively The bonding energy constants of Cd, Zn, and Cu for the soils were in the order of Gangseo>Bonryang>Gyorae soils. The adsorption maxima of Cd, Zu, and Cu for the Bonryang soil increased with compost treatment by $100{\sim}210%,\;90{\sim}230%$, and $130{\sim}290%$ respectively, while little difference was observed when the soil was treated with humic acid Bonding energy constants of Cd, Zn, and Cu for the Bonryang soil increased significantly with compost treatment, and showed insignificant correlation with humic acid treatment.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.1
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• pp.29-34
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• 2009

This study was performed under four operational conditions for nitrogen removal in metal finishing wastewater. The conditions include electrode gap, reducing agent, the recycling of treated wastewater in 1st step and the simultaneous treatment of nitrate and other materials. Result showed that the removal efficiency of $NO_3{^-}-N$ was highest at the electrode gap of 10 mm. As the electrode gap was shorter than 10 mm, the removal efficiency of $NO_3{^-}-N$ decreased due to increasing in concentration polarization on electrode. And, in case that the electrode gap was longer than 10 mm, the removal efficiency of $NO_3{^-}-N$ increased with an increase in energy consumption. Because hydrogen ions are consumed when nitrate is reduced, reducing reaction of nitrate was effected more in acid solution. As 1.2 excess amount of zinc was injected, the removal efficiency of $NO_3{^-}-N$ increased due to increasing in amount of reaction with nitrate. As the effluent from 1st step in the reactor was recycled into the 1st step, the removal efficiency of $NO_3{^-}-N$ increased. Because the zinc were detached from the cathode and concentration-polarization was decreased due to formation of turbulence in the reactor. The presence of $NH_4{^+}-N$ did not affect the removal efficiency of $NO_3{^-}-N$ but the addition of heavy metal decreased the removal efficiency of $NO_3{^-}-N$. As chlorine is enough in wastewater, the simultaneous treatment of nitrate and ammonia nitrogen may be possible. The problem that heavy metal decrease the removal efficiency of $NO_3{^-}-N$ may be solved by increasing current density or using front step of electrochemical process for heavy metal removal.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.606-611
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• 2016

In this work, the treatment of heavy metals and phenol in the contaminated soil was investigated by applying direct current (DC) and pulse voltage. When the DC was used, the removal efficiencies for Cu, Zn, As, and Pb were 73, 88, 10, and 10%, respectively, and more than 95% for phenol was removed. Furthermore, when a pulse voltage was employed the removal efficiencies for Cu, Zn, As, and Pb were 88, 92, 40, and 40%, respectively, and 87% of phenol was removed. The results indicate that the application of a pulse voltage for the treatment of contaminated soil reduced electro-osmosis, but increased the rate of electric current movement of heavy metals. In addition, the removal efficiencies for As and Pb have been improved due to the enhanced adsorption capacity of clay components in the soil. Therefore, these experimental results could be effectively applied in remediation technology for the treatment of various heavy metals and phenol.

• Resources Recycling
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• v.10 no.1
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• pp.25-31
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• 2001

The heat treatment of PVC film containing PVC 65ft, DOP (Dioctyl Phthalate) 32% as plasticizer, Ca-Zn stearates and sur-face agent was performed under several conditions to study the dehydrochlorination of PVC and char production. In the case of $H_2$ $SO_4$, the dehydrochlorination was ca.100% at $250^{\circ}C$ for 3h. The char involving the smaller pores was produced with hydro-thermal treatment. The pore size became small with increasing the treatment time and temperature. In the case of treatment with $Ca(OH)_2$, the sizes of pores produced in char were about sever ~10 $\mu\textrm{m}$ at$ 225^{\circ}C$ for 12h. In the case of $_2$$SO_4$, the size of pores were about 1 $\mu\textrm{m}$ in 5M $_H2$$SO_4$for 12h.

• Resources Recycling
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• v.11 no.4
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• pp.37-43
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• 2002

As the consumption of galvanized steels in cans and automobiles and the quantity of scraps increase, the recycling problems of EAF dust become a important problem. Valuable metals such as Fe, Zn, Pb are of continued interest to metallurgists. To recover the valuable metal and to remove the toxicity of EAF dust, high temperature smelting process is or researching as a pilot scale. The Reduction kinetics of Zn in EAF dust is so important in a view of the economic consideration of the process. In this study, the kinetics behavior of Zn in EAF dust were measured as a point of application in high temperature smelting process. The rate control step in ZnO and franklinite is revealed to be chemical reaction on the reaction surface.

• Journal of the Korean Chemical Society
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• v.21 no.6
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• pp.427-433
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• 1977

A neutron activation method has been developed for the simultaneous determination of chromium, iron, lanthanum, scandium and zinc in river-water samples. The sample is sealed in the silica ampoule without pretreatment and irradiated for a week at a thermal neutron flux of $1{\times}10^{13}n{\cdot}cm^{-2}{\cdot}sec^{-1}$. After cooling for about two days, the elements in the sample are sequentially extracted at different pH by 0.1M oxine-chloroform solution. The organic layers are checked by Gamma-ray spectrometry with $″3\;{\times}\;3″$ NaI (T1) detector connected to a 800-channel pulse hight analyzer. The ppb concentration of the elements in most of river-water samples could be determined by this method. The tracer study for the quantitative separation of the elements was also carried out.

• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.1056-1061
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• 1994

Adhesion between cord and rubber compound of brass plated steel cords pretreated at $80^{\circ}C$ in air and at $80^{\circ}C$ and 85% of relative humidity was studied. Surface change of brass with pretreatment was also studied. Brass was oxidized at thermal treatment and oxidation was accelerated with water at humid treatment. Adhesion of pretreated cords decreased with treatment period. The decreasing tendency of rubber coverage was severe. Decrease in adhesion properties due to brass oxidation was discussed relating to the overgrowth of zinc oxide layer.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.502-507
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• 2016

This study was conducted to develop novel antimicrobial nano-composites, with the aim of fully utilizing antimicrobial properties of multi-walled carbon nanotubes (MWCNTs), nickel (Ni) and zinc oxide (ZnO). Ni coated-MWCNTs (Ni-CNT) were prepared and evaluated for their potential application as an antimicrobial material for inactivating bacteria. Field emission scanning electron microscopy (FE-SEM), and X-ray energy dispersive spectroscopy (EDS) were used to characterize the Ni coating and morphology of Ni-CNT. Staphylococcus aureus (S. aureus) and Escherichia coil (E. coil) were employed as the target bacterium on antimicrobial activities. Comparing with the nitric acid treated MWCNTs and Ni-CNT which have been previously reported to possess antimicrobial activity towards S. aureus and E. coil, Ni-CNT/ZnO exhibited a stronger antimicrobial ability. The nickel coating was confirmed to play an important role in the bactericidal action of Ni-CNTs/ZnO composites. Also, the addition of ZnO to the developed nanocomposite is suggested to improve the antimicrobial property.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.163-163
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• 2017

철강재는 대량 생산이 가능하여 경제성이 뛰어나고 기계적 성질도 우수하여 다양한 산업 분야에서 널리 사용되고 있다. 그러나 철강재는 부식 환경에 취약하기 때문에 그 용도에 따라 다양한 내식성을 부여하는 표면처리를 적용하고 있다. 이러한 철강재에 대한 내식성 표면처리로는 용융아연도금(HDG)과 용융알루미늄도금(HDA)이 우수한 내식성과 다양한 특성으로 널리 사용되고 있으며 아연과 알루미늄을 접목시킨 갈바륨(GL)도금 또한 우수한 내식성 코팅으로 알려져 있다. 또한 최근에는 기존 용융아연도금에 알루미늄(Al) 과 마그네슘(Mg)을 첨가한 3원계 도금강판이 개발되어 기존 용융도금강판 대비 고내식 코팅으로 알려져 있으며 그 적용은 점차 확대되고 있는 추세이다. 일반적으로 이와 같은 강판소재의 내식성 평가에 대해서는 실제 사용할 환경에 폭로하여 비교-시험 하는 것이 가장 확실하고 신뢰도가 높은 방법이다. 그러나 이러한 방법은 경우에 따라 수년에서 수십년에 이르는 장시간이 소요된다. 그러므로 이 방법을 대체하기 위한 각종 가속적 부식 시험들이 널리 적용되고 있다. 즉, 그 목적이나 용도에 따라 염수분무(SST), 침지(Immersion) 및 전기화학적 분극(Polarization) 등 실내에서 부식 시험 하는 방법이 사용되고 있다. 한편, 이러한 부식 가속 시험들은 실제 외부에서 폭로 시험한 결과와의 상관성이 불명확한 경우가 많아 종종 해석에 어려움을 갖고 있는 실정이다. 또한 이 시험 방법들은 동일 재료를 시험하더라도 시험방법의 차이에 따라 부식요인이나 해석방법이 다르므로 인해 그 내식성 결과가 다르게 나타날 수 있다. 그 중 시험목적에 따라 전기화학적 분극 또는 임피던스 분광법(EIS)과 건조 및 습윤 등의 부식 환경 인자들을 적용한 복합부식시험(CCT) 방법은 근사한 대안으로 주목받고 있다. 하지만 이들 시험 또한 실제 부식 환경과는 여러 환경 및 요인들이 다르기 때문에 그 시험방법에 따라 목적하는 시험 결과가 상이하게 나타날 수 있어 해석-평가 하기에 종종 곤란을 갖는다. 이에 따라 최근에는 재현성이 우수하고 실제 부식 환경을 유사하게 모사할 수 있는 내식성 시험과 해석-평가에 대한 내용이 주요한 과제로 사료되고 있다. 본 연구에서는 다양한 내식성 코팅 강판소재들에 대하여 염수분무(SST), 복합부식(CCT), 갈바닉 시험, EIS 시험을 통하여 부식시험 종류 및 시험 환경, 코팅 소재 별 부식경향을 비교-분석하고자 하였다. 또한 이들 부식 진행과정에서는 미세구조관찰(SEM), 결정구조 분석(XRD) 및 원소조성 분석(EPMA)을 통해 다양한 조건에 따른 강판소재들의 부식경향을 비교-평가하고, 실제 환경과의 상관성 및 가속관계를 도출하고자 하였다.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.433-442
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• 2006

Hexavalent chromium passivation, as very effective anti-corrosion method, can not be used in the field of surface treatment for metal, any more. Throughout the world, this regulations which was applied to automotive industries will be extended to all industries including electronics industries in the near future. Therefore a new anti-corrosion method should be established without delay, and trivalent chromium passivation as an alternatives replace the hexavalent chromium passivation for the time being. This paper gives an overview of the currently available trivalent chromium passivation processes, and then it attempts to give an insight to develop a more effective trivalent chromium conversion coating process for possible substitution of the hexavalent chromium passivation process.