Search Results
You are looking at 1 - 10 of 69 items for
- Author or Editor: Y. Kim x
- Refine by Access: All Content x
Abstract
The chromatographic separation of magnesium isotopes was investigated by chemical ion exchange with 1,16-dithia-4,7,10,13-tetraazacyclooctadecane-4,7,10,13-tetramerrifield peptide resin[N4S2·4M] synthesized recently. The capacity of novel N4S2 azacrown ion exchanger was 0.34 meq/g dry resin. The heavier isotopes of magnesium concentrated in the resin phase, while the lighter isotopes are enriched in the solution phase. The glass ion exchange column used was 30 cm long with inner diameter of 0.2 cm, and the 1.0M NH4Cl solution was used as an eluent. The separation factors of24Mg−25Mg,25Mg−26Mg, and24Mg−26Mg were 1.047, 1007, and 1.008, respectively.
Abstract
The elution chromatographic separation of magnesium isotopes was investigated by chemical ion exchange with the synthesized 1,7-dioxa-4,10,13-triazacyclopentadecane-4,10,13-trimerrifield peptide resin [N3O2·3M]. The capacity of novel N3O2 azacrown ion exchanger was 0.21 meq/g dry resin. The heavier isotopes of magnesium concentrated in the resin phase, while the lighter isotopes are enriched in the solution phase. The glass ion exchange column used in our experiment was 30 cm long with inner diameter of 0.2 cm, and the 2.0M NH4Cl solution was used as an eluent. The separation factors of 24Mg-25Mg, 25Mg-26Mg, and 24Mg-26Mg were 1.030, 1.009, and 1.027, respectively.
Abstract
A study on the separation of lithium isotopes was carried out with 1,13-dioxa-4,7,10-triazacyclopentadecane-4,7,10-trimerrifield peptide resin [N3O23M]. The resin having N3O2 as an anchor group has a capacity of 0.2 meq/g dry resin. Upon column chromatography [0.1 cm (I.D)×30 cm (height)] using 1.0M NH4Cl solution as an eluent, a single separation factor of 1.00104 was obtained from the elution curve and isotope ratios based on theGlueckauf theory. The heavier isotope,7Li concentrated in the resin phase, while the lighter isotope,6Li enriched in the solution phase.
Abstract
The relative ans single comparator methods have been applied to determine 7 rare-earth elements and U, Th in Korean Monazites by 14.5 MeV neutron activation analysis. The (n, 2n) nuclear reactions are used for all elements except La, for which (n, p) reaction is used. Al is used as a flux monitor for the relative method and as a singlle comparator for the single comparator method. The analytical results obtained by the two methods agree well within 3% deviation except for Sm and Gd. These results are also compared with the result obtained by a single comparator method using reactor neutron.
Abstract
Absorption spectroscopic properties for various Pu oxidation states in nitric and hydrochloric acid solutions were investigated with UV-Visible spectrophotometry. As a result, it was confirmed that the intensities of the major absorption peaks had a tendency to decrease for Pu(III), Pu(IV) and Pu(VI) in HCl and HNO3 media, and the major peak positions were shifted to longer or shorter wavelengths depending on the complexforming abilities of Pu(III), Pu(IV) and Pu(VI) with the chloride or nitrate ion with increasing acid concentrations. The values of the wavelength and the molar absorptivity for the principal peaks of Pu(III), Pu(IV) and Pu(VI) in NHO3 and HCl solutions were similar to those reported in other works. The values of the molar absorptivity for the principal peaks of Pu(III), Pu(IV) and Pu(VI) in the HNO3 solution were a little higher than those in the HCl solution.
Abstract
Electrochemical behavior of NpO2 2+ on platinum (Pt) and glassy carbon (GC) electrodes have been studied in an aqueous 3M HNO3 solution using cyclic voltammetry and spectroelectrochemical method. The NpO2 2+ species was found to be reduced to Np(V) quasi-reversibly with the formal redox potential of +0.907 V (Pt) and +0.909 V (GC). The reduction process of NpO2 2+ in an aqueous 3M HNO3 solution was also followed spectroelectrochemically by using an optical transparent thin layer electrode cell. It was found that the absorption spectra measured at the applied potentials in the range of +1.05 to +0.65 V have isosbestic points at 1051 and 1124 nm and the evaluated electron stoichiometry is 0.93. These results indicate that the reduction product of NpO2 2+ is NpO2 +. Further details for reaction mechanism of Np(VI) are discussed on the basis of digital simulation of the experimental cyclic voltammograms.
Abstract
A study on the separation of lithium isotope was carried out with a 1,16-dioxa-4,7,10,13- tetraazacyclooctadecane-4,7,10,13-tetramerrifield peptide resin [N4O2·4M]. The resin having N4O2 as an anchor group has a capacity of 3.8 meq/g. Upon column chromatography [0.15 cm (I.D)×29 cm (height)] using 0.01 M NH4Cl as an eluent, the single separation factor, α=1.038 was obtained by the Glueckauf theory from the elution curve and isotope ratios.
Abstract
Kinetics of a thermal dechlorination and oxidation of gadolinium oxychloride (GdOCl) originating from a molten salt process was investigated under various oxygen partial pressures by using a non-isothermal thermogravimetric (TG) analysis. The results of isoconversional analysis of the TG data suggests that the dechlorination and oxidation of GdOCl follows a single step reaction and the observed activation energy was determined as 137.7�4.1 kJ mol−1. The kinetic rate equation was derived for a conversion of the GdOCl with a linear-contacting boundary reaction model. The power dependency for oxygen and the pre-exponential factor was determined as 0.306 and 1.012 s−1 Pa−0.306, respectively.
This study aimed to develop a chromatographic method to quantitatively determine phenol in fish tissues. This method involves solvent extraction of acidified samples, followed by derivatization to phenyl acetate and analysis with gas chromatography coupled with mass spectrometry (GC–MS). Phenol in a representative tissue sample (belly, gill, or renal tubules), which was homogenized with 2 N sulfuric acid, was extracted with ethyl acetate and derivatized to phenyl acetate using acetic anhydride and K2CO3 in water. An n-butyl acetate extract was injected into the GC–MS. The linearity (r 2) of the calibration curve was greater than 0.996. The analytical repeatability, which is expressed as the relative standard deviation, was less than 6.14%, and the recovery was greater than 96.3%. The method detection limit and the limit of quantitation were 8.0 μg/kg and 26 μg/kg, respectively. The proposed method is also applicable to the analysis of other biological tissues for phenol and its analogs, such as pentachlorophenol.
