• Korean Journal of Materials Research
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• v.11 no.12
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• pp.1020-1027
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• 2001

Powder type Ag system insert metals were manufactured by mechanical alloying method. Alloying method was the ball milling process using zirconia ball media, and all alloying variables were constant except the milling time. The milling times were selected 24, 48 and 72 hours. The insert metals made by milling method were observed using scanning electron microscope and x-ray analyses. And also, the evaluation of wettability and microstructures of the insert metals were conducted to investigate the characteristics of the brazed joint. The wettability of the insert metals made by milling of 48 hours, was the best condition. And the insert metals contained Cd shows good wettability, however, there was the oxides residue on the brazing test specimen. The microstructures of the manufactured and the commercial insert metals were almost same displaying the Cu- rich proeutectic and Ag-rich eutectic. Further, there were some porosities. The 48 hours alloyed insert metal was exhibited the most sound brazed joint without containing porosity due to the superior wettability and good alloying condition.

• Journal of Environmental Health Sciences
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• v.23 no.2
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• pp.98-105
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• 1997

The study on the cytotoxicity of heavy metals was carried out to evaluate the cytotoxic effect of those on mouse L929 fibroblast cell in 96-well microtiter plates. The cytotoxicity was assayed by the neutral red, tetrazolium MTT, total protein, micronuclei test. The cytotoxicity of the heavy metals by neutral red and tetrazolium MTT was showed in order, cadmium > zinc > nickel for the cationic metals tested. The effect of metal-metal interaction on the cytotoxicity showed a marked reduction of cadmium toxicity by zinc, to a lesser degree, by nickel. The amount of total protein in treated group added heavy metals was less than that of the control and treated cadmium alone was less than those of combination with nickel or zinc. At midpoint cytotoxicity values of heavy metals, the frequency of micronuclei on the cell treated heavy metals was more than that of control and treated cadmium alone was more than those of combination with nickel or zinc. From those results, it could be suggested that the heavy metals decreased the viability of mouse fibroblast L929 cells in a concentration-dependent manner and have cytogenic toxic effects, but mixed group decreased the cytotoxic and cytogenic toxicity on L929 cells.

• Environmental Engineering Research
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• v.23 no.1
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• pp.92-98
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• 2018

Suitability of aluminium-based water treatment sludge (WTS), a waste product from water treatment facilities, was assessed for removal of heavy metals from an electroplating wastewater which had high concentrations of copper and chromium along with other heavy metals. Batch tests with simulated wastewater in single- and multi-metal solutions indicated the influence of initial pH and WTS dose on removal of six metals namely Cu(II), Co(II), Cr(VI), Hg(II), Pb(II) and Zn(II). In general, removal of cationic metals such as Pb(II), Cu(II) and Zn(II) increased with increase in pH while that of anionic Cr(VI) showed a reduction with increased pH values. Tests with multi-metal solution showed that the influence of competition was more pronounced at lower WTS dosages. Column test with diluted (100 times) real electroplating wastewater showed complete removal of copper up to 100 bed volumes while chromium removal ranged between 78-92%. Other metals which were present in lower concentrations were also effectively removed. Mass balance for copper and chromium showed that the WTS media had Cu(II) and Cr(VI) sorption capacities of about 1.7 and 3.5 mg/g of dried sludge, respectively. The study thus indicates that WTS has the potential to be used as a filtration/adsorption medium for removal of metals from metal-bearing wastewaters.

• Korean Journal of Microbiology
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• v.20 no.1
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• pp.27-40
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• 1982

The effects of heavy metals on the growth rate and phosphate metabolism of Chlorella elliposidea cells were investigated. Chlorella cells were cultured in the media treated with Hg(0.3, 0.7, 0.9 ppm), Cd(1, 5, 15ppm), and Zn(1, 5, 50ppm) for 6days. Aliquots cells were taken out at the inoculation and at intervals during the culture, and measured packed cell vlolume and optical density. The inhibitions of heavy metals on the growth rate and chlorophyll contents were traced. Also after 6 days culture, the amounts of inorganic phosphate and organic compounds of various fractions in Chlorella cells were observed. The turbid effects of heavy metals on the growth rate and chlorphyll contents of Chlorella cells were in order of Hg>Cd>Zn. Because heavy metals depressed the biosynthesis of inorganic polyphosphates and nucleic acids and turn over of inorganic phosphates, the amounts of various phosphate compounds were decreased. The inhibitory effect of photosynthesis by heavy metals resulted in lower contents of carbohydrate. Due to the turbidity of biosynthesis of amino acids by heavy metals, contents of protein were reduced in comparison with those of control. It is suggested conciusively that the minimum concentrations affected by heavy metals on the growth rate and phosphate metabolism of Chlorella cells were 0.7 ppm Hg, 15ppm Cd, 50ppm Zn.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.130-131
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• 2016

Although many metals contaminated sediment from coastal area contain both anionic and cationic heavy metals, the current remediation technologies are not effective for stabilize heavy metals of both anionic and cationic elements from contaminated coastal region. the present work investigated the efficiency and mechanism of immobilization of Fe, Zn, Cr, Cu, Pb and Cd metal solutions in modified zeolite based biostimulant ball. Biostimulant ball containing acetate, nitrate and sulphate which are enhance the activity of marine microorganisms and it can act as electron donors and electron acceptors. Modified zeolite and chelating agent is greatly enhance the metal stabilization due to increased immobility of the analysed metals. The XRD, FT-IR and SEM of modified zeolite which cheating agents containing heavy metals were investigated. The results indicated that heavy metals could be effectively immobilized in modified zeolite and chelating agents in BSB added sediment. The immobilization of heavy metals in modified zeolite and chelating agents along with BSB could be due to stabilize of heavy metal cations. Immobilization of heavy metals using BSB with modified zeolite and chelating agent has lower cost effect and enhance the sediment quality.

• Journal of the Korean Electrochemical Society
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• v.15 no.3
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• pp.135-148
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• 2012

Ionic liquids are steadily attracting interests throughout a recent decade and their application is expanding into various fields including electrochemistry due to their unique properties such as non-volatility, inflammability, low toxicity, good ionic conductivity, wide electrochemical potential window and so on. These features make ionic liquids become an alternative solution for electrodeposition of metals that cannot be electroplated in aqueous electrolytes. In this review, we classify investigated metals into three categories, which are light (Li, Mg), refractory (Ti, Ta) and noble (Pd, Pt, Au) metals, rather than covering the exhaustive list of metals and try to update the recent development in this area. In electrodeposition of light metals, granular fine Li particles were successfully obtained while the passivation of electrodeposited Mg layers is an obstacle to reversible deposition-dissolution process of Mg. In the case of refractory metals, the quality of Ta and Ti deposit particles was effectively improved with addition of LiF and pyrrole, respectively. In noble metal category, EMIM TFSA ionic liquid as an electrolyte for Au electrodeposition was proven to be effective and BMP TFSA ionic liquid developed a smooth Pd deposit. Pt nanoparticle production from ionic liquid droplet in aqueous solution can be cost-effective and display an excellent electrocatalytic activity.

• Journal of environmental and Sanitary engineering
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• v.17 no.3
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• pp.7-13
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• 2002

The removal efficiency of heavy metals by chitosan complex isolated from biological industrial waste was investigated through laboratory experiments. The results of the study are as follows. The adsorption kinetics of heavy metals were reached the equilibrium adsorption in approximately 30 minutes and the removal efficiency were showed 70.7～97.4%. The effect of temperature on heavy metals adsorption by chitosan complex shows that as the temperature increased, the amount of heavy metals adsorption per unit weight of chitosan complex increased. The correlation between amount of heavy metals adsorption per unit weight of chitosan complex and temperature were obtained through the coefficient of determination($R^2$). $R^2$ values were 0.75(p<0.05), 0.99(p<0.05) and 0.98(p<0.05) in Hg, Mn, and Zn, respectively. The injected chitosan complex in which 0.1 g was adsorpted highly and the removal of heavy metals was found to have the best removal efficiency A linearized Freundlich equation was used to fit the acquired experimental data. As a result, Freundlich constants, the adsorption intensity(I/n) was 0.5564, 0.4074, 0.5244 on the Hg, Mn, Zn, respectively And the measure of adsorption(k) was 2.2144, 1.6963, 2.0792 on the Hg, Mn, Zn, respectively. So, it was concluded that adsorption of heavy metals by chitosan complex is effective.

• The Plant Pathology Journal
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• v.28 no.4
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• pp.446-452
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• 2012

The effect of heavy metals on seedling growth and pigment levels was studied in Arabidopsis using essential (Cu, Mn, and Zn) and non-essential metals (Pb and Hg). Generally increasing the concentrations of the metals resulted in a gradual decrease in root and shoot lengths, a decrease in chlorophylls, an increase in anthocyanins and a fluctuation in carotenoid content depending on the metal types. The toxicity of the metals decreased in the following order: Cu > Hg > Pb > Zn > Mn. Among the five metals, Cu was exceptionally toxic and the most potent inducer of anthocyanins. Pb induced the smallest quantity of anthocyanins but it was the strongest inducer of carotenoids. It suggests that the Cu-stressed Arabidopsis may use anthocyanins as its main antioxidants while the Pb-stressed Arabidopsis use carotenoids as its main protectants. All of the five metals induced an accumulation of anthocyanins. The consistent increase in anthocyanin content in the metal-stressed Arabidpsis indicates that anthocyanins play a major role in the protection against metal stresses.

• Journal of Powder Materials
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• v.20 no.2
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• pp.107-113
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• 2013

In this study, the microstructure and valuable metals dissolution properties of PDP waste panel powders were investigated as a function of milling parameters such as ball diameter size, milling time, and rotational speed during high-energy milling process. The complete refinement of powder could achieved at the ball diameter size of 5 mm due to sufficient impact energy and the number of collisions. With increasing milling time, the average particle size was rapidly decreased until the first 30 seconds, then decreased gradually about $3{\mu}m$ at 3 minutes and finally, increased with presence of agglomerated particles of $35{\mu}m$ at 5 minutes. Although there was no significant difference on the size of the particle according to the rotational speed from 900 to 1,100 rpm, the total valuable metals dissolution amount was most excellent at 1,100 rpm. As a result, the best milling conditions for maximum dissolving amount of valuable metals (Mg: 375 ppm, Ag 135 ppm, In: 17 ppm) in this research were achieved with 5 mm of ball diameter size, 3min of milling time, and 1,100 rpm of rotational speed.

• Journal of Environmental Science International
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• v.8 no.4
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• pp.515-523
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• 1999

Nine trace metals (Zn, Fe, Al, Pb, Mn, Cu, Ni, Cr, and Cd) and Se concentrations were determined in organs and tissues(muscle, bone, kidney, liver and skin) of the striped field mice, Apodemus agrarius collected at Daejeo-dong, Pusan city and the Sorak Mt., Kangwon Province. All the trate elements were detected from all the mice examined. As for the metal concentrations in the mice from Daejeo-dong, Zn, Fe, Al, Mn, Ni and Cr were significantly higher than those in Sorak Mt.(p<0.05), suggesting that pesticides including Zn and factory wastes containing several metals might contaminated the environment of Daejeo-dong. As regards the element concentrations in each organ and tissue, Fe, Al, Pb, Mn, Cu, Cr and Cd concentrations were high in liver or kidney; Zn in skin and bone; Ni in bone, skin and kidney; and Se in muscle, liver and skin in all the mice examined. There were significant differences(p<0.05) between juveniles and adults in average concentration of metals(Zn, Fe, Pb, Mn, Ni, and Cd) in every organs and tissues of mice collected at Daejeo-dong. Much higher average levels of metals in juveniles indicate that considerable burdens fo metals might be transferred through the placenta. However, there were no significant differences between males and females, and between young and old adults in average metal concentrations, which suggests that the mice might accumulate the metals during their life time, although they might excrete the metals not only through reproductive activities, such as parturition, lactation and ejaculation of semen, but also through molting, judging from higher accumulating ratios of most metals in skin of adults than of juveniles.