• Journal of the Mineralogical Society of Korea
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• v.26 no.3
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• pp.151-160
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• 2013

A column experiment was carried out to study the reaction of Cr(VI) with organic carbon. Chemical analysis for the effluent collected at different times after the reaction of Cr(VI) with organic carbon in compost and SEM observation for the solid samples remaining after the reaction were conducted. Cr(VI) supplied to the column was not detected in the effluent from column at initial stage, but the concentration of Cr(VI) increased abruptly and maintained the initial supplied concentration (20 mg/kg), indicating that Cr(VI) was effectively removed from the solution at the first state. In general, the concentrations of cations and anions with the exception of $PO_4$ increased and decreased again. Considering that most of these ions were not detected or showed very low concentration, these ions are considered to originate from the organic carbon in the column. SEM observation showed that Cr was coprecipitated with Fe on the surface of organic carbon with small amount of other metals such as Mn, No, and Co. This indicated that on the reduction condition on the organic carbon, Cr(VI) was reduced to $Cr(OH)_3$ and coprecipitated with $Fe(OH)_3$, and that Fe is very important in the precipitation of Cr. After the soluble Fe and Mn are not dissolved any more, $Cr(OH)_3$ is not precipitated. Different from other ions, the concentrations of $PO_4$ decreased and increased, which was thought to be the result of the release of $PO_4$ from organic carbon and sorption on the precipitates. After the maximum sorption on the precipitates and no further release of Fe, the concentration of $PO_4$ returns to its original value measured for the ones released from the organic carbon.

• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.418-429
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• 2011

Novel chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), copper(II), ruthenium(III), and zirconyl(II) complexes of $N^1,N^2$-bis(3-((3-hydroxynaphthalen-2-yl)methylene-amino)propyl)phthalamide ($H_4L$, 1) have been synthesized and characterized by elemental, physical, and spectral analyses. The spectral data showed that the ligand behaves as either neutral tridentate ligand as in complexes 2-5 with the general formula $[H_4LMX_2(H_2O)]{\cdot}nH_2O$ (M=Cu(II), Ni(II), Co(II), X = Cl or $NO_3$), neutral hexadentate ligand as in complexes 10-12 with the general formula $[H_4LM_2Cl_6]{\cdot}nH_2O$ (M=Fe(III), Cr(III) or Ru(III)), or dibasic hexadentate ligand as in complexes 6-9 with the general formula $[H_2LM_2Cl_2(H_2O)_4]{\cdot}nH_2O$ (M = Cu(II), Ni(II), Co(II) or Mn(II), and 13 with general formula $[H_4L(ZrO)_2Cl_2]{\cdot}8H_2O$. Molar conductance in DMF solution indicated the non-ionic nature of the complexes. The ESR spectra of solid copper(II) complexes 2, 5, and 6 showed $g_{\parallel}$ >g> $g_e$, indicating distorted octahedral structure and the presence of the unpaired electron in the $N^1,N^2$ orbital with significant covalent bond character. For the dimeric copper(II) complex $[H_2LCu_2Cl_2(H_2O)_4]{\cdot}3H_2O$ (6), the distance between the two copper centers was calculated using field zero splitting parameter for the parallel component that was estimated from the ESR spectrum. The antibacterial and antifungal activities of the compounds showed that, some of metal complexes exhibited a greater inhibitory effect than standard drug as tetracycline (bacteria) and Amphotricene B (fungi).

• Journal of the Mineralogical Society of Korea
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• v.23 no.4
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• pp.281-295
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• 2010

This paper deals with magnetic susceptibility, mineralogy, soil properties (pH, EC, CEC, loss on ignition), iron and manganese oxides, the content and partitioning of heavy metals (As, Cd, Cr, Cu, Ni, Pb, Zn), and their mutual relationship in the soil samples of an unpolluted, abandoned mine area, and industrial complex area. The various minerals derived from weathered bedrock were identified by X-ray diffraction in the unpolluted soil samples, except for the magnetic minerals. XRD analysis also revealed the existence of hematite and magnetite related to mine tailings and waste rocks in the abandoned mine area samples. The industrial complex area samples had carbonate minerals, such as calcite and dolomite, that might be due to anthropogenic deposition. The sum of the reducible, oxidizable, and residual fractions was over 80% for the abandoned mine area samples and over 50% for the industrial complex area samples using the sequential extraction method. The industrial complex area samples had a relatively high carbonate fraction that was associated with carbonate minerals. The content of aqua regia-extractable Fe, Mn, As, and Zn had a high positive correlation with the content of the dithionite-citrate-bicarbonate (DCB)-extractable method related to Fe/Mn oxide phases. The 54% and 58% of aqua regia-extractable Fe and As content, respectively, acted together with the concentrations of the DCB-extractable phases. Magnetic susceptibility values of total samples ranged from 0.005 to $2.131{\times}10^{-6}m^3kg^{-1}$. The samples including iron oxide minerals, such as hematite and magnetite, had a high magnetic susceptibility. The magnetic susceptibility showed a significant correlation with the heavy metals, Cd (r=0.544, p<0.05), Cr (r=0.714, p<0.01), Ni (r=0.645, p<0.05), Pb (r=0.703, p<0.01), and Zn (r=0.496, p<0.01), as well as Fe (r=0.608, p<0.01) and Mn (r=0.615, p<0.01). The aqua regia-extractable Fe and Mn content had a significant positive correlation with Cd, Cr, Cu, Ni, and Zn. However, the DCB-extractable Fe and Mn content had a significant positive correlation with As and Ni, indicating that the heavy metals were associated with Fe and Mn oxide minerals.

• Journal of Soil and Groundwater Environment
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• v.17 no.6
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• pp.33-42
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• 2012

This study was performed to find the problems according to interference factors (organic matter, pH, Cr, Mn, Fe, clay, and etc.) when we analyzed the hexavalent chromium [Cr(VI)] in soils using UV/VIS spectrometer (US EPA 7196A), attempted to evaluate the domestic applicability of analytical method (US EPA 7199) using IC-UV/VIS spectrometer as alternative method. The recovery rate of certified reference materials was 75.0% (US EPA 7196A) and 101.4% (US EPA 7199) by the analytical methods. As the results of performing QA/QC about US EPA 7199, method detection limit (MDL) and limit of quantification (LOQ) were 0.062 mg/kg, 0.196 mg/kg, respectively. The LOQ of US EPA 7199 was lower than that of the current soil official testing method in Korea (0.5 mg/kg). Cr(VI) contents in 23 soil samples were compared by the analytical methods of EPA 7196A and 7199. Cr(VI) was detected in 13 of 23 soil samples by EPA 7196A, while EPA 7199 was not detected in any soil samples. The Cr(VI) content in 23 soil samples by EPA 7196A was not clearly correlated with Cr, Fe, Mn and clay content in the soil samples. However, the contents of Cr(VI) and organic matter of the soil samples had the highest coefficient of determination ($R^2$) of 0.80. In order to evaluate the correlation between the recovery rates of Cr(VI) and organic matter contents in the soil samples, the recovery rates of 5 soil samples added Cr(VI) standard solution were analyzed by the analytical methods. According to the results, the higher the organic matter contents in soil samples, the lower the recovery rates of Cr(VI) by US EPA 7196, while in case of US EPA 7199, the recovery rates were stable regardless of the organic matter contents.

• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.258-261
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• 2001

The paper industry produces about 6,000 ton of paper ashes yearly with by-products in Yuhan-Kimberly Ltd. The paper ashes was analyzed and evaluated for their potential as the soil acidity amendment materials. This study was conducted to investigate a reasonable amount of paper ashes for soil acidity amendment effect to be applied onto raising seedling of Calendula officinalis L. The mixed proportion of applied ashes, which was compared with agricultural lime, was treated to 0, 5, 10 and 15% (v/v) in mixed soil (pH 6.0) and the peat moss (pH 3.8) respectively. Consequently paper ashe was found to be more effective than agricultural lime at germination percentage, growth condition and in sharp initial increase of soil pH. The appropriate proportion of applied paper ash was 10% (v/v) at the soil-mix, and 15% (v/v) at the peat-moss. Soil application of paper ashes may provide supplemental quantities of K, Ca, Mg and other plant nutrients. But heavy metal concentrations in paper ash was low and should not limit application rates.

• Journal of the Korean Chemical Society
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• v.19 no.4
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• pp.225-232
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• 1975

The elution behaviour of molybdate and tungstate through anion exchange column has been studied at the various pH. A discussion is made to evaluate the equilibrium constants of the polymerization of these acids comparing with the behaviour of chromate ion and dichromate ion. The eqailibrium constants found at $20^{\circ}$ are $K = 4{\times}10^{53} for 7MoO_4^{2-} + 8H^+ {\longleftrightarrow} Mo7O_{24}^{6- }+ 4H_2O$$ K = 3{\times}10^{54} for 6WO_4^{2-} + 7H^+ {\longleftrightarrow} HW6O_{21}^{5-} + 7H_2O$ referring to this results the conditions of separation of tungstate and molybdate are obtained. iThe quantitative separations of carbonate, molybdate and tungstate from the pregnant solution have been established by anion exchange chromatography, using the $22 cm{\times}44.27 cm^2$ column of Rexyn 201. The optimum eluents for the quantitative separation of those ions are as follows; 0.2M solution of sodium chloride at pH 8 for carbonate, the mixture of 0.5 M ammonium chloride and 0.05 M sodium sulfate at pH 5 for molybdate and 0.5 M solution of ammonium chloride at pH 10 for tungstate. Tungstate is directly recovered from the pregnant solution as a form of ammonium paratungstate, by eluting with ammonium chloride solution.

• Journal of the Korean Wood Science and Technology
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• v.46 no.5
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• pp.449-470
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• 2018

A review of research trends on wood surface protection for exterior use obtained the following conclusions: It has been reported that inorganic compounds such as chrome and copper used as wood preservatives can protect wood from weathering. It has been shown that precoating with hydrophobic substances such as wax and oil, UV absorbers, and HALS (Hindered Amine Light Stabilizers) enhances weathering resistance on the surface of ACQ-treated wood. Opaque coatings of paint/stains and semitransparent stains on the surface of preservative treated wood can increase the synergistic effects on prevention of weathering deterioration. Also the need for repainting periodically for the protection of the preservative treated wood surface has also been suggested. ZnO or $TiO_2$ of fine particles, metal ions such as Co, Cr, Fe, Mn, Ni and Ti, and UV absorbers such as tris-resorcinol triazine derivatives, triazine and benzotriazole were introduced as additives for preventing UV in the transparent coating on wood. Several reports showed that chemical modification such as methylation, acetylation, or alkylations have made some increases the effects of preventing weathering with the increasing weight gain of chemical formulas. In heat-treated wood, there were various contradictory reports on the resistance of weathering, and there were some other reports emphasizing the necessity of painting with UV resistance, which leads to the necessity of more advanced studies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.6015-6022
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• 2013

It has been known that there are large amount of nitric acid and valuable metals, copper in the plating waste solution of automobile wheel. As nitric acid and valuable metals are high price and toxic, they should be recovered for economics and environment. Plating waste was extracted with TBP diluted with kerosene. The concentration of nitric acid in aqueous phase was analyzed by titration method by NaOH solution (0.1~1.0N) and the amount of metals by ICP-MS and ICP-AES. The concentration of copper in plating waste were 76,850 mg/L. The concentration of nitric acid in plating waste was 1.02 M. After three step extraction was performed with 50% TBP, each organic phase was stripped three times with distilled water to obtain 48.1% of nitric acid. Purity of final nitric acid was over 99.9% by ICP analysis. After recovery of nitric acid, copper was extracted with various solvent extractors like PC 88A, D2EPHA, LIX 84 and ISE 106. Among these extractors, 92% of copper was recovered by ISE 106 after 1st extraction and 30% $H_2SO_4$ stripping. Copper ion was reduced with $N_2H_4$ to make metal powders, respectively.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.2
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• pp.212-234
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• 1999

Dental restorative materials must have the physical properties to withstand wear and corrosion. Base metal alloys possess better mechanical properties and lower price than the gold alloys. For these reasons such alloys have largely replaced the precious metal alloys. One aspect to con-sider is the release of metal substances to oral environment. The release of elements from dental alloys is a continuing concern because the elements may have the potentially harmful biological effects on local tissues. The purpose of this study was to minimize metal release on the nonprecious metal surfaces by ion beam assisted deposition(IBAD) of titanium nitride (TiN) Ni-Cr-Be alloys with and without TiN coatings were secured in an wear test machine opposing ruby ball to determine their relative resistance to wear with loom, 200m, 300m and 400m sliding distance. And the corrosion behavior of the Ni-Cr-Be alloys with and without TiN coatings and 3 dental noble alloys have been studied. Potentiodynamic curves were used to analyse the corrosion characteristics of the alloys. The measurement of the released Ni and Cr ions was conducted by analysis of the electrolyte solution with atomic absorption spectroscopy. The results were as follows : 1. The critical sliding distance that wore down TiN coatings of $2.5{\mu}m$ thickness in this study condition was 300m. 2. Ion beam assisted deposition of TiN showed a good surface modification with respect to the properties of wear and corrosion resistance. 3. X-ray diffraction showed that the strongest peak of TiN is TiN(111) in the coatings. 4. The release of Ni and Cr ions from alloys measured by means of atomic absorption spectroscopy was reduced by ion beam assisted deposition of TiN.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.4
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• pp.391-405
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• 2020

Leaching chracteristics of Andong-dam sediment was conducted for heavy metal and nutrients. Five mixed sediment samples were prepared and leaching was conducted under aerobic and anaerobic condition for 60 days. Cd, Cu, Pb, Cr, Zn, Hg, As, Fe, Mn, phosphorus, and nitrogen were analyzed at each sampling time. The leaching rate of phosphorus was higher in anaerobic condition comparing with that of under aerobic condition. Some samples showed higher than the water-quality level IV. In case of As and Cd which showed highest contamination level in the sediment, leached concentration were 0.028 mg/L and 0.003 mg/L in maximum, respectively. The leached concentration is below than the lake water quality standard of Korea. Other heavy metals including Cu, Pb, and Cr also showed similar trend. Five step sequential extraction showed that easily extractable 1-2 step portion such as ion-exchangeable and adsorbed one was less than 10% and the most of the portion was residual. For As and Cd, the residual portion were 80% and 95% respectively indicating the risk by the heavy metal leaching into the lake for a short period was not high in comparing with the contamination levels.