• Bulletin of the Korean Chemical Society
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• v.21 no.5
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• pp.538-540
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• 2000

• Resources Recycling
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• v.14 no.6 s.68
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• pp.60-63
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• 2005

It was possible to understand the adsorption characteristics of ions in aqueous environment based on the variations of PZC and IEP of particles when adsorption of ions on particle surface occurred. The specific adsorption of $Cu^{2+}$ ion upon chalcopyrite surface provoked a lowered PZC, which was considered to be due to increased adsorption of OH- ion via the electrostatic attraction between the two ions. On the contrary, IEP of chalcopyrite was observed to rise when Cu2+ was specifically adsorbed on its surface. The reason for this could be explained by the necessity of the increase of pH to offset the positively increased surface potential of chalcopyrite for the reestablishment of IEP. Neither PZC or IEP of chalcopyrite was observed to change when non-specific adsorption occurred since no change in the surface potential of chalcopyrite was invoked under this condition.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.2
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• pp.107-115
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• 2023

Cobalt can be released into the natural environment as industrial waste from the alloying industry and as acid mine drainage, and it is also a radionuclide (⁶⁰Co) that constitutes high-level radioactive waste. Smectite is a mineral that can be useful for adsorption and isolation of this element. In this study, Cheto-type montmorillonite (Cheto-MM), which is the source clays of The Clay Mineral Society (CMS) and already well-characterized, was used. The effect of the adsorption site affected by the presence of interlayer water on the adsorption of cobalt before and after dehydration by heating was evaluated and the adsorption mechanism of cobalt on Cheto-MM was studied by applying adsorption kinetics and adsorption isotherm models. The results showed that the adsorption characteristics changed with dehydration and subsequent shrinkage, and cobalt was found to be adsorbed at the edge of Cheto-MM for about 38% and adsorbed at the interlayer site for about 62%, suggesting that the cobalt adsorption of Cheto-MM is significantly influenced by the interlayer. By applying the adsorption kinetic models, the cobalt adsorption kinetics of Cheto-MM is explained by a pseudo-second-order model, and the concentration-dependent adsorption was best described by the Langmuir isotherm adsorption model. This study provides basic knowledge on the adsorption characteristic of cobalt on montmorillonite with different adsorption sites and is expected to be useful in predicting the adsorption behavior of smectite in high-level radioactive waste disposal sites in the future.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.27.2-27
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• 2003

• Journal of Environmental Health Sciences
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• v.32 no.4 s.91
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• pp.336-341
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• 2006

The biological wastewater treatment system is known to have an important role in reducing the quantify of enteric virus in water environments. To clarify the roles of activated sludge microbes in decreasing the virus infectivity, the behavior of the virus in bacteria, protozoa, and metazoa was examined by pure or mixed culture system using poliovirus type 1(Lsc, 2ab strain). In the bacterial culture systems, the virus infectivity in the liquid phase decreased by a reversible adsorption of the virus to the bacteria or bacterial flocs. On the other hand, in the protozoa and the metazoa culture systems using T. pyriformis and P. erythrophthalma, respectively, with a variety of bacterial strains as prey, the main virus decrease mechanism of reversible adsorption in early stage was changed to irreversible predation, which was not eluted in this study. The virus decrease was more effective in the P. erythrophthalma culture system, which had high predation and floc forming abilities. However, in the mixed culture system of Z. ramigera and P. erythrophthalma, the more rapid reversible adsorption of virus to Z. ramigera flocs preceded the irreversible predation of P. erythrophthalma.

• Macromolecular Research
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• v.16 no.7
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• pp.637-643
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• 2008

A combination of magnetic and temperature-responsive properties in the same polymer composites is expected to increase their potential applications in the biomedical field. Accordingly, micron-sized magnetite/polystyrene/poly(2-dimethylaminoethyl methacrylate-ethyleneglycol dimethacrylate), which are abbreviated as $Fe_3O_4$/PS/P (DM-EGDM) composite polymer particles, were prepared by the seeded copolymerization of DM and EGDM in the presence of magnetite/polystyrene ($Fe_3O_4$/PS) particles. $Fe_3O_4$/PS/P(DM-EGDM) composite particles with magnetic properties showed a temperature-sensitive phase transition at approximately $31^{\circ}C$. The adsorption behavior of the low molecular weight emulsifiers and trypsin (TR) as biomolecules were examined on $Fe_3O_4$/PS/P(DM-EGDM) composite polymer particles at different temperatures. The native conformation of TR was followed by measuring the specific activity under various adsorption conditions. The activity of the adsorbed TR on composite polymer particles was higher than those of the tree TR and TR adsorbed on $Fe_3O_4$/PS particles.

• Journal of the Korean Society of Clothing and Textiles
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• v.43 no.5
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• pp.753-767
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• 2019

Dyeing behavior of indigo leaf powder was examined in regards to the effect of the amount of pigments on color and dye adsorption for silk dyed by reduction and nonreduction dyeing. The amount of indigotin and indirubin pigments adsorbed in dyed silk was examined by HPLC-DAD analysis. The color of dyed silk showed 7.7BG - 2.7B hue when silk was dyed at $50^{\circ}C$, and 3.5G - 4.9BG when dyed at $70^{\circ}C$. Blue ($b^*$) and green ($a^*$) color decreased as the pH of dyebath increased. When silk was dyed using nonreduction, R (red) and RP (red purple) hue and R hue was more apparent in samples dyed at $90^{\circ}C$. In reduction dyeing, amount of indigotin detected from silk exceeded the amount that was initially contained in the input dye. The amount of indirubin was lower than indirubin that was initially in the powder. In nonreduction dyeing, silk showed a higher amount of indirubin adsorption compared to silk dyed by reduction. The amount of indigotin adsorbed in silk was lower than the amount initially contained in the input dye. The amount of indigotin and indirubin adsorption was primarily dependent upon the dyeing method-reduction or nonreduction along with dyeing temperature and the pH of dyebath.

• Korean Journal of Materials Research
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• v.33 no.5
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• pp.195-204
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• 2023

Micro-electronic gas sensor devices were developed for the detection of carbon monoxide (CO), nitrogen oxides (NO_x), ammonia (NH₃), and formaldehyde (HCHO), as well as binary mixed-gas systems. Four gas sensing materials for different target gases, Pd-SnO₂ for CO, In₂O₃ for NO_x, Ru-WO₃ for NH₃, and SnO₂-ZnO for HCHO, were synthesized using a sol-gel method, and sensor devices were then fabricated using a micro sensor platform. The gas sensing behavior and sensor response to the gas mixture were examined for six mixed gas systems using the experimental data in MEMS gas sensor arrays in sole gases and their mixtures. The gas sensing behavior with the mixed gas system suggests that specific adsorption and selective activation of the adsorption sites might occur in gas mixtures, and allow selectivity for the adsorption of a particular gas. The careful pattern recognition of sensing data obtained by the sensor array made it possible to distinguish a gas species from a gas mixture and to measure its concentration.

• Membrane and Water Treatment
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• v.6 no.5
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• pp.393-409
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• 2015

Zinc and lead pollution are public environmental issues that have attracted lots of attention for a long time. Landfill leachate contains heavy metals, such as Zn(II) and Pb(II), which are usually related to the pollution of groundwater, especially in developing countries. Bentonite has been proven to be effective in enhancing the membrane property of clay, by which landfill liners can have better barrier performance towards the migration of contaminants. In this study, 5% sodium bentonite amended with locally available Fukakusa clay was utilized to evaluate the membrane behavior towards the heavy metals zinc and lead. The chemico-osmotic efficiency coefficient, ${\omega}$, was obtained through Zn(II) and Pb(II) solutions with different concentrations of 0.5, 1, 5, 10, and 50 mM. According to the results, ${\omega}$ continually decreased as the Zn(II) and Pb(II) concentrations increased, which is consistent with the Gouy-Chapman theory. Compared to normal inorganic ions, the membrane behavior towards heavy metal ions was lower. The migration of heavy metal ions was not observed based on experimental results, which can be attributed to the adsorption or ion exchange reaction. The mechanisms of the membrane performance change were discussed with the assistance of XRD patterns, free swelling results, XRF results, and SEM images.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.109.1-109.1
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• 2015

Understanding the reaction mechanisms and structures underlying the adsorption of biomolecules on semiconductors is important for functionalizing semiconductor surfaces for various bioapplications. Herein, we describe the characteristic behavior of a primary nucleobase adsorbed on the semiconductor Ge(100). The adsorption configuration of guanine, a primary nucleobase found in DNA and RNA, on the semiconductor Ge(100) at an atomic level was investigated using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. When adsorbed on Ge(100) at room temperature, guanine appears dark in STM images, indicating that the adsorption of guanine on Ge(100) occurs through N-H dissociation. In addition, DFT calculations revealed that "N(1)-H dissociation through an O dative bonded structure" is the most favorable adsorption configuration of all the possible ones. We anticipate that the characterization of guanine adsorbed on Ge(100) will contribute to the development of semiconductor-based biodevices.