• Bulletin of the Korean Chemical Society
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• v.13 no.6
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• pp.620-624
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• 1992

The analytical performance of glow discharge mass spectrometer (GD-MS), using a flat type ion source is discussed. The efficiency of ion extraction was maximized at the distance between anode and cathode of 6 mm. At the operation condition of 4 mA, -1000 volt, and 1 mbar for the source, the optimum voltages for sampler and skimmer were40 volt and -280 volt, respectively. The intensities of Cu, Zn, and Mn were increased as a function of square root of current approximately. Korea standard reference materials (KSRM) were tested for an application study. The detection limits of most elements were obtained in the range of several ppm at the optimized operating condition. The peaks of aluminum and chromium were interfered by those of residual gases. The depth profile of nickel coated copper specimens (3, 5, 10 ${\mu}m$ thickness) were obtained by plotting time versus intensities of Ni and Cr after checking the thickness of nickel coated using a scanning electron microscope (SEM). At this moment, the sputtering rate of 0.2 ${\mu}m/min$ at the optimum operating condition was determined from the slope of the plot of time to the coating thickness. The roughness spectra of specimen's crater after 16 min, discharge were obtained using a Talysuf5m-120 roughness tester as well.

• Resources Recycling
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• v.31 no.1
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• pp.12-20
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• 2022

The smelting reduction of spent lithium-ion batteries results in metallic alloys containing Co, Cu, Fe, Mn, Ni, and Si. A process to separate metal ions from the sulfuric acid leaching solution of these metallic alloys has been reported. In this process, ionic liquids are employed to separate Fe(III) and Cu(II). In this study, D2EHPA and Cyanex 301 were employed to replace these ionic liquids. Fe(III) and Cu(II) from the sulfate solution were sequentially extracted using 0.5 M D2EHPA with three stages of cross-current and 0.3 M Cyanex 301. The stripping of Fe(III) and Cu(II) from the loaded phases was performed using 50% (v/v) and 60% (v/v) aqua regia solutions, respectively. The mass balance results from this process indicated that the recovery and purity percentages of the metals were greater than 99%.

• Korean Journal of Materials Research
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• v.15 no.10
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• pp.626-631
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• 2005

GaN-related compound semiconductors were grown on the corrugated interface substrate using a metalorganic chemical vapor deposition system to increase the optical power of white LEDs. The patterning of substrate for enhancing the extraction efficiency was processed using an inductively coupled plasma reactive ion etching system and the surface morphology of the etched sapphire wafer and that of the non-etched surface were investigated using an atomic force microscope. The structural and optical properties of GaN grown on the corrugated interface substrate were characterized by a high-resolution x-ray diffraction, transmission electron microscopy, atomic force microscope and photoluminescence. The roughness of the etched sapphire wafer was higher than that of the non-etched one. The surface of III-nitride films grown on the hemispherically patterned wafer showed the nano-sized pin-holes that were not grown partially. In this case, the leakage current of the LED chip at the reverse bias was abruptly increased. The reason is that the hemispherically patterned region doesn't have (0001) plane that is favor for GaN growth. The lateral growth of the GaN layer grown on (0001) plane located in between the patterns was enhanced by raising the growth temperature ana lowering the reactor pressure resulting in the smooth surface over the patterned region. The crystal quality of GaN on the patterned substrate was also similar with that of GaN on the conventional substrate and no defect was detected in the interface. The optical power of the LED on the patterned substrate was $14\%$ higher than that on the conventional substrate due to the increased extraction efficiency.

• Journal of the Korean Applied Science and Technology
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• v.34 no.2
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• pp.210-216
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• 2017

Recovery of low level nitric acid and sulfuric acid ions, which were contained in wastewater of a wet scrubber for de-NOx and de-SOx from ship engines, was attempted as fertilizing materials. This study utilized a selective extraction method using four organic solvents to precipitate the solid salts of ammonium nitrate and ammonium sulfate. The IR analysis showed almost same composition of the extracted ammonium salts with a commercial product, and recovery rate of nitrogen and sulfuric ions was 89% and 80% respectively. It was found that the selectivity and solubility consequently could be the crucial factors to recover the low level ions from the waste scrubbing water.

• Analytical Science and Technology
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• v.12 no.5
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• pp.447-459
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• 1999

A study was conducted to compare three analytical methods for determination of hexavalent chromium in the welding fume. Precision and accuracy arc documented for colorimetric, ion chromatographic, and inductively coupled plasma-optical emission spectroscopic method. Evidence is presented that welding fume can affect the oxidation of trivalent chromium. A simple sonication extraction method, proposed in this study, instead of hot alkaline extraction has the advantage of minimizing the potential for chromium oxidation.

• Analytical Science and Technology
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• v.7 no.1
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• pp.65-78
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• 1994

The herbicide mixture of 7 triazines and 9 phenoxyalkanoic acid esters was simultaneously separated and determinated with the selected ion monitoring by using gas chromatography/mass spectrometry. The extraction recoveries of those herbicides from the reagent water were studied for the organic solvent extraction(LLE) with methylene chloride. The calibration curves of them showed good linearity over the concentration range of 0.2~0.5ng/ml and the detection limits were 0.2~0.5ng/ml for 100ml of water. This analytical method could be applied to the drinking water and biological sample.

• Analytical Science and Technology
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• v.11 no.4
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• pp.281-291
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• 1998

An analytical method for the simultaneous measurement of trace Cu, Sn, and Bi in blood and urine has been investigated by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Microwave oven was used for the pretreatment of blood samples using nitric acid and hydrogen peroxide in a closedvessel digestion system with 1 mL whole blood for 8 minutes. Amberlite IRC-718 resin was used as a solid phase in solid-liquid extraction technique for the removal of matrix interferences such as Na, S, P, and other polyatomic ion species. Detection limits for Cu, Sn, and Bi by this method were 0.000375 ng/mL, 0.000297 ng/mL, and 0.000174 ng/mL, respectively. Recoveries of 99.1% for Cu, 102.5% for Sn, and 98.4% for Bi were obtained for the standard spiked NIST SRM 955a blood sample. The developed method was applied for whole real blood and urine samples.

• Analytical Science and Technology
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• v.14 no.5
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• pp.392-399
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• 2001

The analysis of n-butylbenzene and 1,2-dibromo-3-chloropropane (DBCP) as volatile organic compounds in biota samples was performed by gas chromatography/mass spectrometry-selected ion monitoring mode. The target compounds, n-butylbenzene and DBCP, in biota samples were extracted by headspace solid phase microextraction (SPME) with $100{\mu}m$ polydimethyl siloxane (PDMS) fiber and purge & trap method. The extraction recoveries of these compounds obtained by SPME was 85.8% for n-butylbenzene and 92.4% for DBCP, respectively. Each value of method detection limit were $0.15{\mu}g/kg$ and $0.05{\mu}g/kg$, respectively. While in the case of purge & trap method, the extraction recovery was 115.2% for n-butylbenzene, 80.9% for DBCP and method detection limit were $0.04{\mu}g/kg$ and $0.70{\mu}g/kg$, respectively. The extraction yields and detection limits of these compounds obtained by purge & trap were equivalent to those by SPME.

• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4265-4269
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• 2011

A method based on ethyl acetate extraction and gas chromatography with tandem mass spectrometry was developed for determining tetraconazole residues in fruits and vegetables. A 10 g homogenized sample was mixed with 10 mL ethyl acetate, shaken vigorously for 3 min, stored at $-20^{\circ}C$ for 15 min, and then vortexed vigorously for 1 min; 1 g NaCl and 4 g anhydrous $MgSO_4$ were added. The clean-up was carried out by applying dispersive solid-phase with 150 mg $MgSO_4$and 50 mg primary secondary amine. Three precursor product ion transitions for tetraconazole were measured and evaluated to provide the maximum degree of confidence. Average recoveries in fruits and vegetables at three levels (0.005, 0.05 and 0.5 mg/kg) ranged from 85.53% to 110.66% with relative standard deviations ($RSD_r$) from 1.3% to 17.5%. The LODs ranged from 0.002 to 0.004 ${\mu}g$/kg, and LOQs ranged from 0.006 to 0.012 ${\mu}g$/kg. This method was also applied to determine tetraconazole residue in cucumber dissipation experiment under field conditions. The half-lives of tetraconazole in cucumber were in the range of 2.1-3.1 days.

• Resources Recycling
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• v.1 no.1
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• pp.58-68
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• 1992

A process development for direct synthesis of high pure ZnO powders from zinc-bearing waste was investigated. This waste contains a 55% of zinc and it was extracted by the sulfuric acid(leaching). After removal of iron ion by precipitation from the zinc solution, the purification through a solvent extraction by the use of D2EHPA as an extractant was carried out. Then, loaded zinc in organic solution was stripped and precipitated simultaneously using a precipitant such as oxalic acid. Then, loaded zinc in organic solution was stripped and precipitated simulataneously using a precipitant such as oxalic acid. The synthesized $ZnC_2O_4$ powders by the precipitation stripping method was calcined to obtain more than 99.9% of ZnO powders. The effect of sulfuric acid concentration, leaching time, pulp density on the extraction of zinc was studied and the optimum conditions for the solvent extraction were obtained through the investigation of purification of zinc solution. The size, morphology and size distribution of synthesized $ZnC_2O_4$ powders were studied in terms of oxalic acid concentration, temperature, surfactant added, precipitation time, etc.