• Bulletin of the Korean Chemical Society
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• v.21 no.4
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• pp.393-400
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• 2000

2,2￠-Dihydroxyazobenzene (DHAB) was attached to poly(ethylenimine) (PEI) to obtain DHAB-PEI. Spectral titration revealed that uranyl, Fe(III), Cu(II), and Zn(II) ion form 1 : 1-type complexes with DHAB attached to PEI. Formation constants for the metal complexes formed by the DHAB moieties of DHAB-PEI were mea-sured by using various competing ligands. The results indicated thatthe concentrations of uranyl, Fe(III), and Cu(II) ions can be reduced to 10 -16 -10 -23 M at p 8 with DHAB-PEI when the concentration of the DHAB moiety is 1 residue M. By using cyanuric chloride as the coupling reagent, DHAB-PEI was immobilized on Sephadex G-25 resin to obtain DHAB-PEI-Seph. Binding of uranyl,Fe(III), Cu(II), and Zn(II) ion by DHAB-PEI-Seph was characterized by using competing ligands. A new method has been developed for characteriza-tion of metal sequestering ability of a chelating resin. Formation constants and metal-binding capacity of two sets of binding sites on the resin were estimated for each metal ion. DHAB-PI-Seph was applied to recovery of metals such as uranium,Fe, Cu, Zn, Pb, V, Mn, and W from seawater. The uranium recovery from seawaterby DHAB-PEI-Seph does not meet the criterion for economical feasibility partlydue to interference by Fe and Zn ions. The seawater used in the experiment was contaminated by Fe and Zn and, therefore, the efficiency of uranium extractionfrom seawater with DHAB-PEI-Seph could be improved if the experiment is carried out in a cleaner sea.

• Resources Recycling
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• v.28 no.1
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• pp.55-61
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• 2019

The extraction behavior of Mo(VI) and W(VI) from dilute chloride solution was investigated by employing amine (Alamine308 and TEHA) and neutral extractants (TOP) in the solution pH range from 2 to 9. W (VI) was selectively extracted over Mo(VI) by these three extractants and TEHA led to the highest separation factor. Without the pretreatment protonation of the tertiary amines, the extraction percentage of the two metal ions decreased steadily to zero as solution pH increased to 9. The extraction behavior of the metals was discussed on the basis of the distribution diagram of each metal. Alamine 308 and TEHA were much better than TOP in extracting and separating the two metal ions.

• Corrosion Science and Technology
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• v.17 no.5
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• pp.225-230
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• 2018

The effects of birch sap, a possible natural corrosion inhibitor, on the corrosion behavior of steel in chloride solution were investigated. The corrosion rate was significantly reduced by the addition of 1~5 mL of birch sap to 500 mL of 3wt% NaCl or 3wt% $CaCl_2$ solution. A remarkable increase in the pitting potential in NaCl solution was observed by the addition of birch sap although it was almost constant in $CaCl_2$ solution. The corrosion rate of steel in both NaCl and $CaCl_2$ birch sap solution without addition of water was higher compared to that of aqueous solution without birch sap as the pH of the birch sap was 4.0. The presence of organic compounds like, fructose, galactose, glucose, and palmitic acid in the birch sap are thought to be adsorbed effectively on the metal surface, which provided corrosion protection. However, the inorganic elements including Na, Ca, K, Mg, Mn, S, etc. present in the birch sap exhibited no role in corrosion inhibition.

• Journal of Environmental Health Sciences
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• v.28 no.5
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• pp.86-92
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• 2002

This study was performed to assets the operating characteristics of food waste composting and co-composting (food waste + sewage sludge) at a compelling facility. The facility was being operated successfully without being affected by kind of composting feed materials. Partial anaerobic condition was detected during food waste composting and co-com-posting, but these two composting systems were proven to be operated successfully under aerobic condition from the monitoring results of $O_2$, volatile solids reduction rate, temperature, and other parameters. The conductivity and chloride concentrations of compost were gradually increased during two composting periods, but the conductivity and chloride concentrations of co-compelling indicated lower values than those of food waste composting at final point(40 m). As a result, co-composting was turned out to be more desirable than food waste composting, considering salt problem. High correlations ($R^2$= 0.9265 for food waste composting and $R^2$= 0.9685 for co-composting) between CEC and volatile organic matter were found. Quality of composts produced from two composting process satisfied Korean heavy metal standard.

• Corrosion Science and Technology
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• v.11 no.6
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• pp.232-241
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• 2012

This work focused on corrosion of carbon steel bolted GECM/Al parts in tap water and NaCl solutions. In tap water and NaCl solutions, open circuit potential of GECM and its potentials in a series of carbon steel bolt>Ti>Al became active. Regardless of test materials, open circuit potentials in tap water were noble, and increasing NaCl concentration, its potentials became active. Immersion test of single specimen showed that no corrosion occur in Ti and GECM. In tap water, carbon steel bolt didn't show red corrosion product and in chloride solutions, corrosion rate in 1% NaCl solution was greater than its rate in 3.5% NaCl solution and red corrosion product in 1% NaCl solution was earlier observed than that in 3.5% NaCl solution. It seems that this behavior would be related to zinc-coatings on the surface of carbon stee l bolt. On the other hand, aluminium was corroded in tap water and chloride solutions. Corrosion of aluminium in tap water was due to the presence of chloride ion in tap water by sterilizing process.

• Journal of Microbiology and Biotechnology
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• v.22 no.5
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• pp.684-689
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• 2012

In the present study, an efficient mercury-tolerant bacterial strain (RS-5) was isolated from heavy-metalcontaminated industrial effluent. Under shake flask conditions, 97% of the supplemented mercuric chloride was sequestered by the biomass of RS-5 grown in a tryptone soy broth. The sequestered mercuric ions were transformed inside the bacterial cells, as an XRD analysis of the biomass confirmed the formation of mercurous chloride, which is only feasible following the reaction of the elemental mercury and the residual mercuric chloride present within the cells. Besides the sequestration and intracellular transformation, a significant fraction of the mercury (63%) was also volatilized. The 16S rRNA gene sequence of RS-5 revealed its phylogenetic relationship with the family Bacillaceae, and a 98% homology with Lysinibacillus fusiformis, a Gram-positive bacterium with swollen sporangia. This is the first observation of the sequestration and volatilization of mercuric ions by Lysinibacillus sp.

• Bulletin of the Korean Chemical Society
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• v.25 no.10
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• pp.1484-1488
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• 2004

The thiocyanate-selective PVC membrane electrodes based on 5,10,15,20-tetrakis(2,4,6-trimethylphenyl)-porphyrinatomanganese(III) chloride [Mn(TMP)Cl] and 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrinatomanganese(III) chloride $[Mn(Cl_8TPP)Cl]$ as ion carriers were investigated. The effect of ionophores, membrane compositions, plasticizers, and solution pHs on the response characteristics were studied. The Mn(TMP)Cl as an ionophore shows the best potentiometric sensitivity with a slope of -58.7 mV/decade and a detection limit of $log[SCN^-]$ = -6.90, and selectivity for thiocyanate over strong hydrophobic interfering anions such as ${ClO_4}^-$ and salicylate. The potentiometric response is affected by the electronic effect of the substituents and solution pHs. The presence of substituents with electron donating and more liphophilic characters around the ligated metal center produces an improved response toward $SCN^-$.

• The Korean Journal of Nuclear Medicine
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• v.34 no.4
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• pp.336-343
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• 2000

Purpose: Thallous-201 chloride produced at Korea Cancer Center Hospital(KCCH) is used in detecting cardiovascular disease and cancer. Thallium impurity can cause emesis, catharsis and nausea, so the presence of thallium and other metal impurities should be determined. According to USP and KP, their amounts must be less than 2 ppm in thallium and 5 ppm in total. In this study, the detection method of trace amounts of metal impurities in $[^{201}Tl]$TICI injection with polarography was optimized without environmental contamination. Materials and Methods: For the detection of metal impurities, Osteryoung Square Wave Stripping Voltammetry method was used in Bio-Analytical System (BAS) 50W polarograph. The voltammetry was composed of Dropping Mercury Electrode (DME) as a working electrode, Ag/AgCl as a reference electrode and Pt wire as a counter electrode. Square wave stripping method, which makes use of formation and deformation of amalgam, was adopted to determine the metal impurities, and pH 7 phosphate buffer was used as supporting electrolyte. Results: Tl, Cu and Pb in thallous-201 chloride solution were detected by scanning from 300 mV to -800 mV Calibration curves were made by using $TINO_3,\;CuSO_4\;and\;Pb(NO_3){_2}$ as standard solutions. Tl was confirmed at -450 mV peak potential and Cu at -50 mV Less than 2 ppm of Tl and Cu was detected and Pb was not detected in KCCH-produced thallous-201 chloride injection. Conclusion: Detection limit of thallium and copper is approximately 50 ppb with this method. As a result of this experiment, thallium and other metal impurities in thallous-201 chloride injection, produced at Korea Cancer Center Hospital, are in the regulation of USP and KP Polarograph could be applied for the determination of metal impurities in the quality control of radiopharmaceuticals conveniently without environmental contamination.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2711-2718
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• 2012

The alkylation of the ambident enolates of a methyl glycinate Schiff base with ethyl chloride was studied at B3LYP and MP2 levels with $6-31+G^*$ basis set. The free (E)-enolates and (Z)-enolate are similar in energy and geometry. The transition states for the alkylation of the free (E)/(Z)-enolate with ethyl chloride have similar energy barriers of ~13 kcal/mol. However, with a lithium ion, the (E)-enolate behaves as an ambident enolate and makes a cyclic lithium-complex in bidentate pattern which is more stable by 11-23 kcal/mol than the (Z)-enolate-lithium complexes. And the TS for the alkylation of (E)-enolate-lithium complex coordinated with one methyl ether is lower in energy than those from (Z)-enolate-lithium complexes by 4.3-7.3 kcal/mol. Further solvation model (SCRF-CPCM) and reaction coordinate (IRC) were studied. This theoretical study suggests that the alkylation of ambident enolates proceeds with stable cyclic bidentate complexes in the presence of metal ion and solvent.

• Journal of Sericultural and Entomological Science
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• v.43 no.1
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• pp.37-40
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• 2001

This study was carried out to investigate the optimum condition for silk sericin collection from degumming solution using some aluminium salts with various treatment conditions and examine the thermal properties of silk sericin collected from degumming solution. Silk sericin was precipitated by treatment of aluminium metal compound from degumming solution. The best optimum collecting conditions of silk sericin from degumming solution are the concentration of 2 $m\ell$/l of polyaluminium chloride (PAC), pH range of 5~7 and room temperature. The reduction of water pollution was evaluated by decreasing the chemical oxygen demand (COD) and nitrate ion (NO$_3$￣). Thermal stability of silk sericin collected from degumming solution was a little lower than that of hot water.