• Economic and Environmental Geology
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• v.48 no.3
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• pp.213-219
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• 2015

Samples from soils and crops were collected and analyzed in order to investigate the interactions of selenium among rocks, soils, and crops by hydrothermal alteration near epithermal mines in the region of Mio-san, Haenam. Soil samples included 6 samples each from mountain and farm area and compositional minerals and their contents were analyzed by water content, pH, ICP, XRD, XRF. Crop samples from onion and scallion were analyzed for chemical composition to elucidate the relationship with soils. Results from XRD analysis for soil samples showed that major compositional minerals are qualtz and feldspar, and illite, chlorite, hematite formed by hydrothermal alteration were included on a small scale. The pH ranges of soil samples from mountain and farm were measured at 4.6~4.9 and 5.2~6.7, respectively. The higher pH in farm soils may result from fertilization during agricultural activities. Results from ICP analysis showed that, compared to soil samples from mountain area with no potassium and calcium, significant amount of K and Ca were detected in soil samples from farms which is affected by fertilization. In a similar manner, potassium and calcium were absorbed and detected in crop samples at relatively high concentrations (116.89~169.79 ppm for K and 20.18~32.29 ppm for Ca). While the selenium contents in soil samples ranged from 18.35 ppb to 70.31 ppb which showed no significant difference, high concentrations of selenium were detected in onion (119.48~179.50 ppb) and scallion (146.65 ppb). These difference in enrichment for each element may result from the distinctive adsorption characteristics depending on crops.

• Applied Chemistry for Engineering
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• v.26 no.5
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• pp.604-608
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• 2015

In the present work, the improvement of nitrate removal ability was investigated to resolve a eutrophication problem by using Ulmus davidiana (U. davidiana) bark generated from Gangwon province. When the initial pH of aqueous solution was adjusted to 3.5 in batch experiments, the removal efficiencies for 10 and 20 mg/L nitrate increased up to 43 and 37%, respectively. In addition, when U. davidiana bark of 1.0 g/100 mL was used for 8 h, the removal efficiency for 20 mg/L nitrate was 68%. Moreover, when reforming reaction of U. davidiana bark was performed under oxyfluorination conditions, the optimal ratio of partial pressure between fluorine and oxygen was 1 : 9 for an enhanced nitrate adsorption amount. When reformed U. davidiana bark was used for 8 h operation under the optimal oxyfluorination condition, removal efficiencies for 10, 20 and 40 mg/L nitrate were found to be 96, 95 and 59%, respectively. Collectively, these results suggest that our water treatment technology can be effectively utilized to treat high concentrations of nitrate in water bodies.

• Clean Technology
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• v.23 no.1
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• pp.95-103
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• 2017

In this study, $ATiO_3$ (A = Ca, Sr, Ba) perovskite, which is the widely known for non $TiO_2$ photocatalysts, were synthesized using sol-gel method. And Ni was added at the A site of $ATiO_3$ by using that it is easy to incorporate. The physicochemical characteristics of the obtained $ATiO_3$ and Ni-$ATiO_3$ particles were confirmed using the X-ray diffraction (XRD) UV-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), the $N_2$ adsorption-desorption isotherm measurement, and X-ray photoelectron spectroscopy (XPS). The $H_2$ was produced using the photolysis of MeOH. Using the Ni-$ATiO_3$ photocatalysts, $H_2$ production was higher than using the $ATiO_3$ photocatalysts. Especially, $273.84mmolg^{-1}$ $H_2$ was produced after 24 h reaction over the Ni-$SrTiO_3$. Also in the water (0.1 M KOH) with the Ni-$SrTiO_3$, $H_2$ production was $961.51mmolg^{-1}$ after 24 h reaction.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.12
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• pp.1677-1685
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• 2012

The autolysate and hydrolysate of a common squid liver, Todarodes pacificus, were prepared. Autolysis (liver ratio, pH, temperature) and Protamex-treated hydrolysis (pH, temperature, ratio of protease to liver) conditions were optimized by response surface methodology using central composite design for under 1 hr of hydrolysis time. The desirability profile indicated that maximum DH could be achieved at a squid liver of 93.5%, pH 6.4, and $47^{\circ}C$ in autolysis, while that of Protamex-treated hydrolysis did at a Protamex-to-squid liver level of 0.33%, pH 6.0, and $55^{\circ}C$. Three amino acids, proline, cysteine, and methionine, were not detected in the total amino acid composition of the Protamex-treated hydrolysate, while they were detected in the free amino acid composition. Cadmium was $8.32{\pm}0.03$ mg/100 g-powder for raw, $3.56{\pm}0.02$ mg/100 g-powder for the autolysate, and $13.26{\pm}0.04$ mg/100 g powder for the Protamex-treated hydrolysate. The major molecular weight ranged from 1.0 to 1.5 kDa for the autolysate and from 210 to 470 Da for the Protamex-treated hydrolysate. Food functionalities of the autolysate, such as surface hydrolphobicity, emulsion activity index, emulsion stability, water, and fat adsorption, were similar to the Protamex-treated hydrolysate. Both the autolysate and Protamex-hydrolysate showed high inhibitory activities on the angiotensin-I converting enzyme. Cell toxicity against the HepG2 cell line was not detected in the autolysate or the Protamex-treated hydrolysate by 200 ${\mu}g/mL$.

• KSBB Journal
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• v.17 no.2
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• pp.153-157
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• 2002

A fusion protein, consisting of a human epidermal growth factor as the recognition domain and human angiogenin as the toxin domain, can be used as a targeted therapeutic against breast cancer cells among others. The fusion protein was expressed as an inclusion body in recombinant E. coli, yet when the conventional solution-phase refolding process was used the refolding yield was very low due to severe aggregation, probably because of the opposite surface charge resulting from the vastly different pl values of each domain. Accordingly the solid-phase refolding process, which exploits the ionic interactions between a solid matrix and the protein, was tried, however the ionic binding yield was also very low regardless of the resins and pH conditions used. Therefore, to provide a higher affinity toward the solid matrix, six Iysine residues were tagged to the N-terminus of the hEGF domain. When cation exchange resins, such as heparin- or CM-Sepharose, were used as the matrix, the adsorption capacity increased 2.5~3-fold and the subsequent refolding yield increased nearly 15-fold compared to the conventional process. A similat result was also obtained when an Ni-NTA metal affinity resin was used.

• Journal of the Mineralogical Society of Korea
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• v.17 no.2
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• pp.157-168
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• 2004

The surface chemical properties of aqueous kaolinite and halloysite were studied using a potentiometric titration experiment and a computer program FITEQL3.2. Among the surface complexation models a constant capacitance model was selected for this study. The 2 sites - 3 p $K_{a}$ s model, in which the surfaces were assumed to have tetrahedral and octahedral sites, was reasonable for the description of the experimental data. The surface charges of both minerals were negative above pH of 4. The higher the pH, the lower the proton surface charge densities of both minerals. The ≡ $SiO^{[-10]}$ site played an important role in cation adsorption in acid and neutral pH range; whereas the ≡ Al $O^{[-10]}$ site was in an alkaline pH range. The optimized intrinsic constants of kaolinite, p $K_{a2(Si)}$$^{int}$, p $K_{al(Al)}$$^{int}$ and p $K_{a2(Al)}$$^{int}$ were 4.436, 4.564, and 8.461 respectively, and those of halloysite were 7.852, 3.885, and 7.084, respectively. The total Si and Al surface sites concentrations of kaolinite were 0.215 and 0.148 mM, and those of halloysite were 0.357 and 0.246 mM. The ratio of Si and Al surface site densities ([≡SiOH]:[≡AlOH]) of both minerals was 1 : 0.69. The total surface site density of kaolinite, 3.774 sites/n $m^2$, was 1.6 times larger than that of halloysite, 2.292 sites/n $m^2$./TEX>.

• Korean Chemical Engineering Research
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• v.51 no.6
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• pp.666-670
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• 2013

Recovery method of silicon wafer from defective products generated from manufacturing process of silicon solar cells was studied. The removal effect of the N layer and antireflection coating (ARC) of the waste solar cell were investigated at room temperature ($25^{\circ}C$) by variation of concentration of $H_3PO_4$, $NH_4HF_2$, and concentration and types of chelating agent. Removal efficiency was the best in the conditions; 10 wt% $H_3PO_4$ 2.0 wt% $NH_4HF_2$, 1.5 wt% Hydantoin. Increasing the concentration of $H_3PO_4$, the surface contamination degree was increased and the thickness of the silicon wafe became thicker than the thickness before surface treatment because of re-adsorption on the silicon wafer surface by electrostatic attraction of the fine particles changed to (+). The etching method by mixed solution of $H_3PO_4$-$NH_4HF_2$-chelating agents was expected to be great as an alternative to conventional RCA cleaning methods and as the recycle method of waste solar cells, because all processes are performed at room temperature, the process is simple, and less wastewater, the removal efficiency of the surface of the solar cell was excellent.

• Applied Chemistry for Engineering
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• v.4 no.1
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• pp.204-215
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• 1993

Epoxy-activated chitin was synthesized by the reaction of epichlorohydrin with chitin which was isolated from waste marine sources such as crab shell. Followed by the reaction of epoxy-activated chitin with hexamethylenediamine, the aminohexyl chitin was synthesized. The aminohexyl chitin was subsequently reacted with epichlorohydrin to prepare the epoxy-activated aminohexyl chitin. Finally, the tannin-immobilized chitin (Resin I) was synthsized by the reaction of tannin solution with epoxy-activated aminohexyl chitin. Using silane coupling agent, the tannin-immobilized chitosan(Resin II) was synthesized by the reaction of $\gamma$-glycidoxypropyltrimethoxy silane with chitosan which was prepared by the deacetylation of chitin. Upon the pH variation, adsorptivities of these immobilized tannins to the metal ions such as $Cu^{+2}$, $Ni^{+2}$, $Cr^{+6}$, $Co^{+2}$, $Ca^{+2}$, $Pb^{+2}$, $Ba^{+2}$, and $UO_2{^{+2}}$ ions were determined by batch method. The adsorptivity tendencies of these immobilized tannin to the most of metallic ions were increased with pH. Furthermore, the adsorptivities of Resin(I) and Resin(II) upon the variation of pH, contact time, amount of resin and concentration of metal ion were investigated. As a result, it was found that these immobilized tannin on both chitin and chitosan showed good adsorptivities for uranyl ion.

• Journal of Korean Society of Forest Science
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• v.90 no.1
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• pp.133-138
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• 2001

Increased base cation loss and Al mobilization, a consequence of soil acid neutralization responses, are common in air polluted areas showing forest decline. The prediction models of acid neutralization responses were developed by using indicators of soil acidification level(pH, and base saturation) in order to assess the forest soil sensitivity to acidification. The soil acidification level was greatest in Namsan followed by Kanghwa, Ulsan, and Hongcheon, being contrary to regional total $ANC_H$ pattern through soil columns leached with additional acid ($16.7mmol_c\;H^+/kg$), Both base exchange and Al dissolution were main acid neutralization processes in all study regions. There were low base exchange and high Al dissolution in the regions of the low total $ANC_H$. The $ANC_M$ by sulfate adsorption was greatest in Hongcheon compared with other regions even though the AN rate was very low as 6.4%. Coefficients of adjusted determination of simple and multiple regression models between soil acidification level indicators and the acid neutralization responses were more than 0.52(p<0.04) and 0.89(p<0.01), respectively. The result suggests that soil pH and base saturation are available indicators for predicting the acid neutralization responses. These prediction models could be used as an useful method to measure forest soil sensitivity to acidification.

• Journal of the Mineralogical Society of Korea
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• v.29 no.2
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• pp.59-71
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• 2016

To investigate the sorption characteristics of Cs, which is one of the major isotopes of nuclear waste, on natural zeolite chabazite, XRD, EPMA, EC, pH, and ICP analysis were performed to obtain the informations on chemical composition, cation exchange capacity, sorption kinetics and isotherm of chabazite as well as competitive adsorption with other cations ($Li^+$, $Na^+$, $K^+$, $Rb^+$, $Sr^{2+}$). The chabazite used in this experiment has chemical composition of $Ca_{1.15}Na_{0.99}K_{1.20}Mg_{0.01}Ba_{0.16}Al_{4.79}Si_{7.21}O_{24}$ and its Si/Al ratio and cation exchange capacity (CEC) were 1.50 and 238.1 meq/100 g, respectively. Using the adsorption data at different times and concentrations, pseudo-second order and Freundlich isotherm equation were the most adequate ones for kinetic and isotherm models, indicating that there are multi sorption layers with more than two layers, and the sorption capacity was estimated by the derived constant from those equations. We also observed that equivalent molar fractions of Cs exchanged in chabazite were different depending on the ionic species from competitive ion exchange experiment. The selectivity sequence of Cs in chabazite with other cations in solution was in the order of $Na^+$, $Li^+$, $Sr^{2+}$, $K^+$ and $Rb^+$ which seems to be related to the hydrated diameters of those caions. When the exchange equilibrium relationship of Cs with other cations were plotted by Kielland plot, $Sr^{2+}$ showed the highest selectivity followed by $Na^+$, $Li^+$, $K^+$, $Rb^+$ and Cs showed positive values with all cations. Equilibrium constants from Kielland plot, which can explain thermodynamics and reaction kinetics for ionic exchange condition, suggest that chabazite has a higher preference for Cs in pores when it exists with $Sr^{2+}$ in solution, which is supposed to be due to the different hydration diameters of cations. Our rsults show that the high selectivity of Cs on chabazite can be used for the selective exchange of Cs in the water contaminated by radioactive nuclei.