• Resources Recycling
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• v.2 no.2
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• pp.27-38
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• 1993

In this study, we investigated the grinding and sedimentation(elutriation) process of the dusts for the effective separation of high purity iron and iron oxides. For characterization of the dust, particle size distribution and chemical composition, were examined. The results obtained in this study may be summarized as follows : 1. The converter CF(clarifier) dust of the Pohang 1st, 2nd steel making factory and EC(Evaporation Cooler), EP(Eltrostatic precititator) dust of the Kwangyang 2nd steel making factory are composed $\alpha$-Fe(21~50%), FeO(wustite)$Fe_3$$O_4$(magnetite), $Fe_2$$O_3$, CaO, $Al_2$$O_3$, $SiO_2$, and etc. 2. Pure iron has ductile characteristic in nature, particle size of the pure iron increase by increasing the grinding time. On the other hand, it is conformed that bo고 particles of hematite and magnetite become less than 325 mesh after 10 minutes grinding. 3. By applying the elutriation technique for the EC dust of the Kwangyang 2nd steel making factory, the iron powder of high content more than 99.17% of pure Fe was recovered with 37.8% yield at grinding time for 40 minutes. 4. By applying the elutriation technique for the CF dust of the Pohang 2nd steel making factory, the iron powder of high content more than 98.38% of pure Fe was recovered with 44.42% yield at grinding time for 40 minutes. 5. When magnetic separation was performed using plastic bonding magnet of 70 gauss, more than 98% Fe grade of iron powder was recovered in the size range +65 -200 mesh but the recovery of it was low.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.3
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• pp.147-153
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• 2011

This study is to measure the differences of the trace-metals resulted from the different ecologies, such as nickel(Ni), copper(Cu), zinc(Zn), cadmium(Cd), plumbum(Pb), arsenic(As) and chrome(Cr) remaining in the parts of Korean Yeongdeok Crab (KYC) and Russian Snow Crab (RSC) based on ICP-MS. The recovery rate of each metal certified the reference materials (CRM) was in the average of 81~99%, which corresponded with the level required in Codex. The level of metals in the parts of KYC was in the order of Ni > As > Zn > Cu > Cr > Cd in the both male and female shell; the order of Zn > As > Cu > Cr > Ni > Cd in the leg flesh; the order of Zn > As > Cu > Cr > Cd > Ni in the body flesh; the order of Cu > Zn > As > Cd > Cr > Ni in the gill; the order of Cu > As > Zn > Cd > Ni > Cr in the male hepatopancreas; the order of Cu > Zn > As > Cd > Cr > Ni in the female hepatopancreas, thereby showing some differences. It was revealed that the levels of most metals (nickel, copper, zinc, arsenic and chrome) were similar between KYC and RSC except cadmium which was somewhat lower than that of KYC. However, the cadmium in RSC was discovered in high level in most of the parts, two times higher in the hepatopancreas, and four times in the gill. It was also revealed that the trace metal contents were changing according to the size of KYC; the metals with the highest level of Ni in shell, Zn in leg and body flesh, Cu in gill tended to decrease as growing, whereas the cadmium contents tended to increase overall and accumulated the most in hepatopancreas. The results showed there was a possibility that the phenomenon of bioaccumulation within hepatopancreas would increase as growing.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.28 no.3
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• pp.175-182
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• 2022

Heavy metals can be intentionally or unintentionally introduced into plastic food utensils, containers, and packaging (PFUCP) as additives or contaminants, which can be ingested with food by humans. Here, seven-heavy metals (lead, cadmium, nickel, chromium, antimony, copper, and manganese) with toxicity concerns were selected, and risk assessment was done by establishing their migration from 137 PFUCP products made of 16 materials distributed in Korea. Migration of heavy metals was examined by applying 4% acetic acid as a food simulant (70℃, 30 minutes) to the PFUCP products. Inductively coupled plasma mass spectrometry (ICP-MS) was employed for the analysis of migrated heavy metals, and the reliability of quantitative results was confirmed by checking linearity, LOD, LOQ, recovery, precision, and expanded uncertainty. As a result of monitoring, heavy metals were detected at a level of non-detection to 8.76 ± 11.87 ㎍/L and most of the heavy metals investigated were only detected at trace amounts of less than 1 ㎍/L on average. However, antimony migrated from PET products was significantly higher than other groups. Risk assessment revealed that all the heavy metals investigated were safe with a margin of exposure above 311. Collectively, we demonstrated that heavy metals migrated from PFUCP products distributed in Korea appear to be within the safe range.

• Korean Journal of Microbiology
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• v.45 no.4
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• pp.411-415
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• 2009

Some microorganisms are capable of leaching Mn(II) from nonsulfidic manganese ores indirectly via nonenzymatic processes. Such reductive dissolution requires organic substrates, such as glucose, sucrose, or galactose, as a source of carbon and energy for microbial growth. This study investigated characteristics of Mn(II) leaching from manganese nodules by using heterotrophic Bacillus sp. strain MR2 provided with corn starch as a less-expensive substrate. Leaching of Mn(II) at 25.6 g Mn(II) $kg^{-1}$ nodule $day^{-1}$ was accompanied with cell growth, but part of the produced Mn(II) re-adsorbed onto residual $MnO_2$ particles after 24 h. Direct contact of cells to manganese nodule was not necessary as a separation between them with a dialysis tube produced similar amount [24.6 g Mn(II) $kg^{-1}$ nodule $day^{-1}$]. These results indicated an involvement of extracellular diffusible compound(s) during Mn(II) leaching by strain MR2. In order to optimize a leaching process we tested factors that influence the reaction, and the most efficient conditions were $25\sim35^{\circ}C$, pH 5~7, inoculum density of 1.5~2.5% (v/v), pulp density of 2~3 g/L, and particle size <75 ${\mu}m$. Although Mn(II) leaching was enhanced as particle size decrease, we suggest <212 ${\mu}m$ as a proper size range since more grinding means more energy consumption The results would help for the improvement of bioleaching of manganese nodule as a less expensive, energy-efficient, and environment-friendly technology as compared to the existing physicochemical metal recovery technologies.

• Journal of Food Hygiene and Safety
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• v.35 no.1
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• pp.23-30
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• 2020

This study investigated the migration levels of lead (Pb), cadmium (Cd), and arsenic (As) from food contact articles (glassware, ceramics, enamelware, and earthenware) into a food stimulant (4% v/v, acetic acid). Migration tests were performed at 25℃ for 24 h and all analyses were performed using Inductively-Coupled Plasma Mass Spectrometry (ICP-MS). The method was validated by linearity of calibration curves, limit of detection (LOD), limit of quantification (LOQ), recovery, precision, and uncertainty. In glassware, the migration concentrations ranged from not-detected (N.D.) to 752.21 ㎍/L and N.D. to 1.99 ㎍/L for Pb and Cd, respectively. In ceramics, the migration concentrations ranged from N.D. to 1,955.86 ㎍/L, N.D. to 74.06 ㎍/L, and N.D. to 302.40 ㎍/L for Pb, Cd, and As, respectively. In enamelware, the migration concentrations ranged from N.D. to 4.48 ㎍/L, N.D. to 7.00 ㎍/L, and N.D. to 52.00 ㎍/L for Pb, Cd, and Sb, respectively. In earthenware, the migration concentrations ranged from N.D. to 13.68 ㎍/L, N.D. to 0.04 ㎍/L, and N.D. to 6.71 ㎍/L for Pb, Cd, and As, respectively. All results were below the migration limits of Korea standards and specifications for food utensils, containers, and packages.

• Korean Journal of Food Science and Technology
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• v.43 no.2
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• pp.230-234
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• 2011

According to the Codex committee, the maximum allowable level for lead in fruits is 0.1 mg/kg. This survey was conducted as a surveillance program following the establishment of safety guideline for fruits in Korea. Concentrations of lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg) were measured in 927 samples using a ICP-MS and a mercury analyzer. The recoveries of microwave digestion method were 86.0-110.4% for Pb, 81.0-104.0% for Cd and 82.0-104.7% for As by standard addition method. The recovery of direct mercury analyzer was 106.5% for Hg. The average levels of Pb in ${\mu}g/kg$ were $10.0{\pm}12.8$ for apple, $8.8{\pm}10.9$ for pear, $4.1{\pm}4.4$ for persimmons, $14.9{\pm}12.3$ for mandarin, $7.1{\pm}6.5$ for orange, $3.1{\pm}3.3$ for banana, $8.8{\pm}8.9$ for kiwi, and $9.3{\pm}9.7$ for mango. The average levels of Cd in ${\mu}g/kg$ were $0.4{\pm}0.3$ for apple, $2.0{\pm}1.6$ for pear, $0.3{\pm}0.3$ for persimmon, $0.1{\pm}0.1$ for mandarin, $0.1{\pm}0.1$ for orange, $1.3{\pm}1.8$ for banana, $0.5{\pm}0.5$ for kiwi, and $0.7{\pm}0.6$ for mango. The average levels of As in ${\mu}g/kg$ were $2.0{\pm}2.1$ for apple, $1.2{\pm}1.3$ for pear, $1.5{\pm}1.2$ for persimmon, $0.8{\pm}0.3$ for mandarin, $1.5{\pm}0.5$ for orange, $1.8{\pm}1.2$ for banana, $1.6{\pm}1.5$ for kiwi, and $1.2{\pm}1.5$ for mango. The average levels of Hg in ${\mu}g/kg$ were $0.5{\pm}0.4$ for apple, $0.3{\pm}0.2$ for pear, $0.2{\pm}0.1$ for persimmon, $0.2{\pm}0.1$ for mandarin, $0.2{\pm}0.1$ for orange, $0.2{\pm}0.0$ for banana, $0.2{\pm}0.2$ for kiwi, and $0.6{\pm}0.2$ for mango. Based on the Korean public nutrition report 2005, these levels (or amounts) are calculated only at 0.17% for Pb, 0.013% for Cd and 0.006% for Hg of those presented in provisional tolerable weekly Intake (PTWI) which has been established by FAO/WHO. Therefore, the levels presented here are presumed to be adequately safe.