• Journal of Soil and Groundwater Environment
• /
• v.13 no.4
• /
• pp.54-61
• /
• 2008

Permeable reactive barriers (PRBs) technology has been focused in contaminated groundwater remediation. It is necessary to select adequate reactive material according to characteristics of contaminant in groundwater. In this research, the reaction between reactive material and heavy metal contaminants was estimated through column test. Reactive material was slag, which has been produced in Gwangyang power plant, and heavy metal contaminants were cadmium, lead and copper. Column test was performed in the condition of 1) single and multi contaminated solution and 2) different initial concentration of cadmium. Retardation factor of cadmium is 3.94 in multi contamination. But that of copper is 40.3 in single and 25 in multi. The difference of retardation between cadmium and copper is due to affinity, resulted from the difference of electronegativity. In multi-contamination, copper effluent concentration was above initial copper concentration and at the same time lead effluent concentration was decreased. This phenomenon was considered that lead extract copper sorbed in slag and then lead was sorbed to the vacant sorption site instead. And as the initial concentration was increased, the retardation factor of cadmium became decreased.

• Proceedings of the KWS Conference
• /
• 2009.11a
• /
• pp.217-220
• /
• 2009

Conductive adhesives have been investigated for use in microelectronics packaging as a lead-free solder substitute due to their advantages, such as low bonding temperature. However, high resistivity and poor mechanical behavior may be the limiting factors for the development of conductive adhesives. The metal fillers and the polymer resins provide electrical and mechanical interconnections between surface mount device components and a substrate. As metal fillers used in conductive adhesives, silver is the most commonly used due to its high conductivity and the stability. However the cost of conductive adhesives with silver fillers is much higher than usual lead-free solders and silver has poor electro-migration performance. So, copper can be a promising candidate for conductive filler metal due to its low resistivity and low cost, but oxidation causes this metal to lose its conductivity. In this study, electrically conductive adhesives (ECAs) using surface modified copper fillers were developed. Especially, in order to overcome the problem associated with the oxidation of copper, copper particles were coated with silver, and the silver-coated copper was tested as a filler metal. Especially the effect of silver coating on the electrical resistance just after curing and after aging was investigated. As a result, it was found that the electrical resistance of ECA with silver-coated copper filler was clearly lower and more stable than that of ECA with pure copper filler after curing process. And, during high temperature storage test, the degradation rate of electrical resistance for ECA with silver coated copper filler was quite slower than that for ECA with pure copper filler.

• Journal of environmental and Sanitary engineering
• /
• v.6 no.1
• /
• pp.83-93
• /
• 1991

For the survey of water pollution, several heavy metals were analyzed in the sediment of the Han River from March 20 to April 22, 1989. The results were as follows : 1. The respective ranges of heavy metal concentrations of Cadimium, Lead, Copper, Zinc and Manganese found in the sediments of the Han River were 0.32!2.41 $\mu g/g$, 15.80~129.64 $\mu g/g$, 13.82~372.36 $\mu g/g$, 58.40~925.40 $\mu g/g$, 271.50~668.30 $\mu g/g$. 2. In the sediment of inflow site Jung Rang Chon the contents of Lead, Copper, Zinc were the highest among other sampling points and An Yang Chon, the contents of Cadmium, was the highest among other sampling points and Wang Sook Chon, the contents of Manganese, was the highest among other sampling points. 3. Through all sampling points general trend of heavy metal contamination showed the highest in Zinc, the next Manganese, Copper, Lead and Cadmium respectively. 4. The higher amount of heavy metal was found in the finer particles of sediment. 5. The amount of Cadmium and Lead of the Han River water was below the standard of environment.

• Journal of the Korean institute of surface engineering
• /
• v.19 no.3
• /
• pp.92-108
• /
• 1986

An electroplating on the lead frame fabricated from domestic copper plate was studied experimentally. In this study, nickel was plated on the thin copper lead frame and silver layer was coated on the nickel film in the cyanide electrolyte. The effect of process variables such as current density, plating time, coating thickness and flow rate of electrolytic solution on the properties of coating was investigated. Some samples on each step were fabricated during electroplating. The results obtained from polarization measurement, observation of SEM photograph, adhesion test of coating and microhardness test are as follows. On silver plating, polarization resistance of potentiostatic cathodic polarization curve is reduced as the flow rate of Ag electrolytic solution increases. And above resistance is also reduced when the minor chemicals of sodium cyanide and sodium carbonate are added in potassium silver cyanide bath. The reduced polarization resistance makes silver deposition on the cathode easy. An increase in the current density and the coating thickness causes the particle size of deposit to coarsen, and consequently the Knoop microhardness of the coating decreases. On selective plating an increase in the flow rate of plating solution lead to do high speed plating with high current density. In this case, the surface morphology of deposit is of fine microstructure with high Knoop hardness. An increasing trend of the adhesion of coating was shown with increasing the current density and flow rate of electrolytic solution.

• Environmental Analysis Health and Toxicology
• /
• v.4 no.1_2
• /
• pp.47-53
• /
• 1989

This survey was performed to find out the heavy metal concentrations in shellfishes. Experimental subjects were 60 cases in 10 kinds of shellfishes purchased in markets in july, august, 1987 and february, 1988. Contents of lead, cadmium, zinc, copper and mangangese were determined by atomic absorption spectrophotometer and mercury contents by mercury analyzer. The results were as follows: The range of mercury contents in shellfishes was from ND to 0.22 ppm, cadmium from 0.22 to 2.46 ppm, lead from 0.09 to 4.90 ppm, copper from 0.62 to 12.45 ppm, manganese from 0.09 to 13.8 ppm and zinc from 4.01 to 129.96 ppm.

• Applied Chemistry for Engineering
• /
• v.27 no.1
• /
• pp.21-25
• /
• 2016

When copper alloy is used in etching process for the production of lead frame, the high concentration of heavy metals, such as iron, nickel and zinc may be included in the etching waste. Those etching waste is classified as a specified one. Therefore a customized design was designed for the purification process of the lead frame etching waste liquid containing high concentrations of heavy metals for the production of an electroplating copper(II) oxide. Since the lead frame etching waste solution contains highly concentrated heavy metal species, an ion exchange method is difficult to remove all heavy metals. In this study, a copper(I) chloride was manufactured by using water solubility difference related to the reduction-oxidation method followed by the reunion of copper(II) chloride using sodium sulfate as an oxidant. The hydrazine was chosen as a reducing agent. The optimum added amount was 1.4 mol per 1.0 mol of copper. In the case of removal of heavy metals by using the combination of reduction-oxidation and ion exchange resin methods, 4.3 ppm of $Fe^{3+}$, 2.4 ppm of $Ni^{2+}$ and 0.78 ppm of $Zn^{2+}$ can be reused as raw materials for electroplating copper(II) oxide when repeated three times.

• The Korean Journal of Pharmacology
• /
• v.17 no.2
• /
• pp.31-36
• /
• 1981

Heavy metals which are present as trace elements in human body have been known to modify various enzymatic reaction. These metals can be essential or non-essential. Zinc, copper and calcium are essential in maintaining some biological processes, whereas non-essential metals such as cadmium, lead and mercury produce accumulatve toxic effect. Cadmium accumulated in pancreas can cause toxicity and damage of pancreatic cells, thereby influencing CHO metabolism. Lead compounds are known to produce toxic effects on the kidney, digestive system and brain fellowed by inhibition of activity of ${\rho}-aminolevulinic$ acid and biosynthesis of hemoproteins and cytochrome. Evidence has been accumulated that zinc not only acts as a cofactor in enzyme reaction but also prevents toxic effect induced by heavy metal such as copper and cadmium. To demonstrate the effect of heavy metals on pancreatic secretion, part of uncinate pancreas was taken and incubated in Krebs-Ringer bicarbonate buffer with heavy metals used. Additional treatment with CCK-OP was performed when needed. After incubation during different period of time, medium was analyzed for amylase activity using Bernfeld's method. The present study was attempted in order to elucidate the effect of several kinds of heavy metal on exocrine pancreatic secretion in vitro. The results obtained are as follows: 1) CCK-OP stimulated significantly amylase release from pancreatic fragments in vitro. 2) CCK-OP response of amylase release from pancreatic fragments was inhibited by treatmant with cadmium, especially high doses of cadmium. 3) CCK-OP response of amylase release from pancreatic fragments was inhibited when pretreated with $10^{-4}M$ copper chloride. 4) Lead chloride at the concentration of $10^{-3}M\;and\;10^{4}M$ stimulated the basal amylase release in vitro but CCK-OP response did not augment by lead chloride. 5) Zine chloride did not affect amylase release from pancreatic fragment in vitro. From the results mentioned above, it is suggested that CCK-OP response was inhibited it the amylase release from pancreatic fragments pretreated with cadmium and copper chloride.

• Microbiology and Biotechnology Letters
• /
• v.41 no.1
• /
• pp.60-69
• /
• 2013

Purified melanin pigment from Klebsiella sp. GSK was characterized by thermogravimetric, differential thermal, X-ray diffraction and elemental analysis. This melanin pigment is structurally amorphous in nature. It is thermally stable up to $300^{\circ}C$ and emits a strong exothermic peak at $700^{\circ}C$. Its carbon, hydrogen and nitrogen composition is 47.9%, 6.9% and 12.0%, respectively. It was used to scavenge metal ions and free radicals. After immobilizing the pigment and using it to adsorb copper and lead ions, the metal ion adsorption capacity was evaluated by atomic absorption spectroscopy (AAS) and the identity of melanin functional groups involved in the binding of metal ions was determined by Fourier transform infrared (FT-IR) spectroscopy. Batch adsorption studies showed that 169 mg/g of copper and 280 mg/g of lead were adsorbed onto melanin-alginate beads. The metal ion adsorption capacity of the melanin-alginate beads was relatively significant compared to alginate beads. The metal ion desorption capacity of HCl was greater (81.5% and 99% for copper and lead, respectively) than that of EDTA (80% and 71% for copper and lead, respectively). The ability of the melanin pigment to scavenge free radicals was evaluated by inhibition of the oxidation of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and was shown to be about 74% and 98%, respectively, compared with standard antioxidants.

• Journal of Life Science
• /
• v.13 no.4
• /
• pp.421-427
• /
• 2003

A natural habit at bacterium, Enterobacter intermedious KH410 was isolated from freshwater plant root and identified. Adsorption of heavy metals such as lead, cadmium, and copper by this strain was examined. The minimal inhibitory concentrations(MIC) for each metal were 1.78 mM for lead, 0.17 mM for cadmium and 1.39 mM for lopper, respectively. Maximum production of dried cell was 2.56 g/$\ell$ in LB medium containing 0.5% NaCl, 1% yeast extract and 1% of lactose. Optimal conditions for adsorption were 0.6 dry g-biomass, at pH 4.0 and the temperature of $20^{\circ}C$. Adsorption equilibrium reached maximum after 30 min in 400 mg/$\ell$ metal solution. The adsorption capacity (K) of copper was 1.5 times higher than that of cadmium and lead was 1.1 times higher than that of cadmium. from the results obtained in this study, Freundlich adsorption model was applicable for all metals. Adsorption strength (1/n) of heavy metal ions were in the order of cadmium>copper>lead. The adsorption of dried cell for lead, cadmium, and copper was 56.2, 58.0, 55.8 mg/g-biomass, respectively. Pretreatment to increase ion strength was the most effective with 0.1 M NaOH whereas slight difference was found both KOH and $CaCl_2$ upon same concentration. Effective desorption was induced by 0.1 M EDTA for lead and 0.1 M $HNO_2$ for cadmium and copper.

• Journal of Welding and Joining
• /
• v.31 no.5
• /
• pp.77-81
• /
• 2013

We have investigated thermal stability of the mechanical and thermal conductive properties of Cu/STS/Cu 3 layered clad metal lead frame material for a LED device package at different temperatures ranging from RT to $200^{\circ}C$. The fabricated Cu/STS/Cu clad metal has a good thermal stability for the mechanical tensile strength and thermal conductivity of the over 50 $Kg/mm^2$ to the $150^{\circ}C$ and 270 $W/m{\cdot}K$ to the $200^{\circ}C$, respectively. This clad metal lead frame material at a high temperature of $150^{\circ}C$ shows a reinforced mechanical tensile strength by 1.5 times to conventional pure copper lead frame materials and also a comparable thermal conductivity to typical copper alloy lead frame materials.