• Journal of the Korean Wood Science and Technology
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• v.51 no.5
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• pp.321-333
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• 2023

In this study, lignin, a lignocellulosic biomass, was chemically modified to produce polyethyleneimine-grafted lignin (PKL) with maximum hexavalent chromium [Cr(VI)] adsorption capacity. Changes in the physicochemical properties due to the cationization of lignin were confirmed through elemental analysis, Fourier transform infrared spectroscopy, and moisture stability evaluation. Alginate (Alg) beads containing PKL (Alg/PKL) were prepared by incorporating cationic lignin into the Alg matrix to apply the prepared PKL in a batch-type water treatment process. The optimal Alg/lignin mixing ratio was selected to increase the Cr(VI) adsorption capacity and minimize lignin elution from the aqueous system. The selected Alg/PKL beads exhibited an excellent Cr(VI) removal capacity of 478.98 mg/g. Isothermal adsorption and thermodynamic analysis revealed that the Cr(VI) removal behavior of the Alg/PKL beads was similar to that of heterogeneous chemical adsorption. In addition, the bulk adsorbent material in the form of beads exhibited adsorption behavior in three stages: surface adsorption, diffusion, and equilibrium.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.1
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• pp.1-7
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• 2006

The spectroscopic characteristics of Pu (III, IV, V, VI) in the HCl media were investigated by measuring Pu oxidation states using a UV-Vis-NIR spectrophotometer (400-1200 nm) after adjusting Pu oxidation states with oxidation/reduction reagents. Pu in stock solution was reduced to Pu(III) with $NH_2OH$ HCl, and oxidized to Pu(IV) and Pu(VI) with $NaNO_2$ and $HClO_4$, respectively. Also, Pu(V) was adjusted in the Pu(VI) solution with $NH_2OH$ HCl. The major absorption peaks of Pu (IV) and Pu(III) were measured in the 470 m and 600 nm, respectively. The major absorption peaks of Pu (VI) and Pu(V) were measured in the 830 nm and 1135 nm, respectively. There was not found to be significant changes of UV-Vis absorption spectra for Pu(III), Pu(IV) and Pu(VI) with aging time, except that an unstable Pu(V) immediately reduced to Pu(III).

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.3
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• pp.133-141
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• 2009

Study on the chemical speciation of uranium(VI) species, ${UO_2}^{2+}$, $UO_2(OH)^+$, ${(UO_2)}_2{(OH)_2}^{2+}$, ${(UO_2)}_3{(OH)_5}^+$, has been peformed by using time-resolved laser-induced fluorescence spectroscopy. Speciation sensitivity which depends on the excitation wavelength was investigated. We obtained the speciation sensitivity in the order of $10^{-9}$ M concentration of U(VI) compounds at the excitation wavelength of 266 nm. The fluorescence spectrum and lifetime of ${UO_2}^{2+}$ were carefully measured at pH 1 and ion strength of 0.1 M. The spectrum showed the four characteristic peaks located around 488, 509, 533, 559nm and the fluorescence lifetime of $1.92{\pm}0.17{\mu}s$. The wavelength shifts of fluorescence peaks and the change of lifetimes for uranium hydrolysis compounds were compared with those of ${UO_2}^{2+}$. We report on the characteristic features, the shifts of peaks to the longer wavelength direction and the prolonged lifetimes, in the fluorescence of the U(VI) hydrolysis compounds.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.1
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• pp.104-118
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• 2009

This study was carried out to classify Korean soybean varieties base on maturity group (MG) and to find character relationships according to planting date for high quality soybean seed production adapted to early season cultivation environment of Miryang. Results of maturity grouping of Korean soybean varieties showed that Keunol (3 cultivars), belonged to Group 0; Seonnok and Danmi in Group II, Shinrok in Group III, Seonyu (17 cultivars), in Group IV, Taekwang (44 cultivars) in Group V, Daewon (25 cultivars) in Group VI, and Kwangdu and Keumdu in Group VII. Agronomic characteristics of 100 soybean varieties were compared based on MG, cultivation year and seeding date. Soybean varieties belonging to the MG $VI{\sim}VII$ showed longer days to flowering and growth period, high lodging density and higher yield. Seed quality analysis revealed that as maturity was delayed, seed weight becomes heavier while seed cracks become abundant. In addition, occurrence of purple seed and phomopsis were higher in MG $0{\sim}III$. Protein content was higher in MG $0{\sim}III$, and isoflavone content was higher as maturity was delayed. On the other hand, lipid content was generally similar across MGs. Correlation analysis of major agronomic characters showed positive relationships between days to flowering and growth days, seed weight and lodging in MG $IV{\sim}V$, seed crack and growth days in MG $0{\sim}III$, seed crack and days to flowering in MG $IV{\sim}V$ and MG $VI{\sim}VII$, seed crack and lodging in MG $IV{\sim}V$ and MG $VI{\sim}VII$, seed crack and seed weight in MG $IV{\sim}V$ and MG $VI{\sim}VII$, purple seed and growth days in MG $IV{\sim}V$, purple seed and seed weight in MG $VI{\sim}VII$, phomopsis and growth days in MG $IV{\sim}V$ and MG $VI{\sim}VII$, and phomopsis and purple seed in MG $IV{\sim}V$ and MG $VI{\sim}VII$. In contrast, a negative relationship was observed between seed weight and lodging in MG $0{\sim}III$. Correlating yield and major characters revealed negative relationships between days to flowering and growth days in MG $0{\sim}III$ and MG $IV{\sim}V$, whereas positive relationships were obtained on MG $VI{\sim}VII$ seeded on April 30. Lodging, seed weight and seed crack were all negatively correlated with yield in the MG $IV{\sim}V$ and MG $VI{\sim}VII$. Soybean cultivars identified as adaptable to early season planting for production of high quality soy curd and fermented soybean paste were Seonyu, Kwangdu, and Soho while those suited for the manufacture of soybean sprouts were Sobaeknanul, Kwangan, Sowon, and Bosuk. Geomjeong 2 chosen as best for mixing with rice.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.2
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• pp.109-114
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• 2009

Absorption spectra for a quantitative analysis of actinide elements such as U(VI) and Pu(V) were measured by using a liquid waveguide capillary cell (LWCC) which has an optical path length of 1.0 meter. In order to investigate radioactive elements, a LWCC is installed in a glove box and is coupled to a spectrophotometer with optical fibers. Limits of detection (LOD) for the system were determined as 0.74 and 0.35 M with molar absorption coefficients of 8.14${\pm}$0.07 (414 nm) and 17.00${\pm}$0.16 (569 nm) $M^{-1}cm^{-1}$ for U(VI) and Pu(V) ions, respectively. The measured LOD values are about 30 times more sensitive when compared to those achievable by using a conventional quartz cell with an optical path length of 1.0 cm. As an application with an enhanced sensitivity, a quantitative analysis for micromolar concentrations of Pu(V) has been performed to decrease the uncertainty in the formation constant of the Pu(VI)-OH complex.

• Journal of the Korean GEO-environmental Society
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• v.3 no.4
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• pp.5-10
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• 2002

Pistia stratiotes(Water Lettuce) can be applied to remove inorganic pollutants from the wastewater for the advanced treatment. This study attempts to remove heavy metals from the secondary treated wastewater. Three different initial concentrations of heavy metals were applied as 0.5, 1.0 and 1.5 mg/L for Lead(Pb) and Chromium(Cr(VI)). In addition, the removal efficiency for the mixture of Lead and Chromium was also observed. The removal efficiency of Pb was in the range of 41.0~72.0% for Pb and it was in the range of 25.0~30.0% for Cr(VI) by Pistia stratiotes. The plants placed in static systems were able to remove the heavy metals in a few days of exposure. However, it was observed that the heavy metals affected produce phytotoxic effects on plants resulting in inhibition of chlorophyl synthesis, decrease in biomass production, and finally plant necrosis. The removal efficiencies of Pb and Cr(VI) by Pistia stratiotes were increased with plant growth.

• Journal of Soil and Groundwater Environment
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• v.15 no.1
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• pp.57-65
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• 2010

Currently, the pursuit of industrialization for rapid economic growth has led to serious environmental damage and related problems because of comtamination with chemicals. Over time, this contaminaion is getting worse and worse. Most developing countries have tried to pursue their economic development and growth, however without preparation for the control and disposal of hazardous wastes. Permitting hazardous waste to be abandoned and disposed in appropriately causes soil pollution, groundwater contamination, and surface water contamination, which are all extremely serious. In particular, when hazardous wastes which include toxic chemicals are distributed around the living environment even in small amounts, concentration can occur in the food chain through ecological systems, which can therefore affect human. Chromium(VI) has contaminated soil in China. We experimented to test the immobilization, chemical reduction, and soil washing methods in order to make our experiment efficient in the purification of soil contaminated with Chromium(VI), and to prove the theoretical models by experiments testing the field applications. The field experiment showed that result of experiment satisfied with the standards of China. The result of multi-stage continuous remediation reduce the Chromium(VI) concentration to 11.95 mg/kg and 14.83 mg/kg that were equivalent to 98% and 97% removal rates. This result implied we could apply multi-stage process of Chromium(VI) contaminated soil to meet the regulatory limit of Chromium(VI).

• Journal of Microbiology and Biotechnology
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• v.15 no.4
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• pp.780-786
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• 2005

The biomass of the brown seaweed, Ecklonia, was used to remove Cr(VI) from wastewater. Previously, Cr(VI) was removed through its reduction to Cr(III) when brought into contact with the biomass. In this study, the effects of ionic strength, background electrolytes, and Cr(III), Ni(II), Zn(II), and Fe(III) on the Cr(VI) reduction were examined. An increased ionic strength inhibited the Cr(VI) reduction. The presence of other heavy metals, such as Cr(III), Ni(II), or Zn(II), only slightly affected the Cr(VI) reduction, while Fe(III) enhanced the reduction. Although the above various parameters could affect the reduction rate of Cr(VI) by Ecklonia biomass, these effects were relatively smaller than those of pH and temperature. In addition, the previously derived rate equation was found to be applicable over a range of ionic strengths and with different background electrolytes. In conclusion, Ecklonia, bioniass may be a good candidate as a biosorbent for the removal of Cr(VI) from wastewaters containing various other impurities, and scale-up to a practical process may be accomplished using the previously derived rate equation.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.57.3-58
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• 2016

A symbiotic star is a wide binary system consisting of a hot white dwarf and a mass losing giant, where the giant loses its material in the form of a slow stellar wind resulting in accretion onto the white dwarf through gravitational capture. Symbiotic stars are known to exhibit unique spectral features at 6825 and 7082, which are formed from O VI 1032 and 1038 through Raman scattering with atomic hydrogen. In this Monte Carlo study we investigate the flux ratio of 6825 and 7082 in a neutral region with a geometric shape of a slab, cylinder and sphere. By varying the amount of neutral hydrogen parametrized by the column density along a specified direction, we compute and compare the flux ratio of Raman scattered O VI 6825 and 7082. In the column density around 1020 cm-2, flux ratio changes in a complicated way, rapidly decreasing from the optically thin limit to unity the optically thick limit as the column density increases. It is also notable that when the neutral region is of a slab shape with the O VI source outside the slab, the optically thick limit is less than unity, implying a significant fraction of O VI photons escape through Rayleigh scattering near the boundary. We compare our high resolution CFHT data of HM Sge and AG Dra with the data simulated with finite cylinder models confirming that 'S' type symbiotic tend to be characterized by thicker HI region that 'D' type counterparts. It is expected that this study will be useful in interpretation of the clear disparity of Raman O VI 6825 and 7082 profiles, which will shed much light on the kinematics and the asymmetric distribution of O VI material around the hot white dwarf.

• Journal of the Korean Chemical Society
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• v.22 no.5
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• pp.320-325
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• 1978

In order to elucidate the mechanism associated with the solvent extraction of uranium(VI) using DEPA and DPPA as extractant the uranium(VI) complexes formed during the solvent extraction were isolated and characterized by means of IR, NMR, chemical analysis and molecular weight determination. It has been found that uranium(VI) replaces the acidic hydrogen ions of the extractants DEPA and DPPA to form chelated polynuclear complexes, the molecular weight of U(VI)-DEPA complex being $2.1{\times}10^4$. The isolated U(VI)-DEPA complex has been found to be the same chemical species as is formed during the solvent extraction process. In case of DEPA the distribution coefficient of uranium is the largest of the pure aqueous uranium solution and is increasing for the acidic solutions in the order of $H_3PO_4.