• Journal of the Korean Ceramic Society
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• v.36 no.7
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• pp.691-697
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• 1999

TiO2 powder was adsorbed on the surface of mica using the heterocoagulation method in water TiO2 powder was prepared from hydrolysis of titanium-iso propoxide in a mixed solvent of anhydrous ethanol and water. When the molar ratio of water to titanium iso-propoxide was 0.25 monodispersed spherical TiO2 particles were obtained. The prepared TiO2 powder showed anatase phase after heat treatment at 50$0^{\circ}C$ for 2 h and then transformed to rutile phase after heat treatment at 100$0^{\circ}C$ for 2h. The iso-electric points of TiO2 and Mica were pH 3.9 and pH 3.25 respectively which were measured by the Z-potential analysis in water base. The maximum Z-potential difference between two powders was observed in the range of pH 3.6~3.7 TiO2 powder was adsorbed on the surface of mica by heterocoagulation method in pH 3.6~3,7 The properties of prepared TiO2 powder was haracterized by TG-DTA, XRD and SEM The morphology and thermal properties of TiO2-adsorbed mica were examined.

• Korean Journal of Materials Research
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• v.18 no.6
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• pp.313-317
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• 2008

[ $LaFeO_3$ ] powders were synthesized using a method involving solution combustion, and the surface properties of these powders were examined by x-ray photoelectron spectroscopy. As the amount of fuel increased during the synthesis, the $LaFeO_3$ powders became amorphous with a large plate-like shape. It was found that the O 1s spectra were composed of two types of photoelectrons by deconvolutioning the spectra. Photoelectrons with higher binding energy come from adsorbed oxygen ($O^-$) whereas those with lower energy come from lattice oxygen ($O^{2-}$). The ratio of adsorbed and lattice oxygen increased as the ratio of the fuel and nitrate (${\Phi}$) increased. The binding energy of both types of oxygen increased as ${\Phi}$ increased due to the formation of carbonates.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2883-2888
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• 2013

To enhance the power conversion efficiency of dye-sensitized solar cell (DSSC), the surface of titanium dioxide ($TiO_2$) photoelectrode was modified by hydroxylation treatment with $NH_4OH$ solution at $70^{\circ}C$ for 6 h. The $NH_4OH$ solutions of various concentrations were used to introduce the hydroxyl groups on $TiO_2$ surface. As the concentration of $NH_4OH$ was increased, the short-circuit current density ($J_{SC}$) value and conversion efficiency of solar cells were increased because the amount of adsorbed dye molecules on $TiO_2$ surface was increased. As a result of the surface modification to introduce hydroxyl groups, the concentration of adsorbed dye on the $TiO_2$ surface could be improved up to 32.61% without the changes of morphology, surface area and pore volume of particles. The morphology, the specific surface area, the pore volume and the chemical states of $TiO_2$ surface were characterized by using FE-SEM, $N_2$ adsorption-desorption isotherms and XPS measurements. The amount of adsorbed dye and the performance of fabricated cells were analyzed by using UV-Vis absorption spectroscopy and solar simulator.

• Journal of the Korean Chemical Society
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• v.14 no.1
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• pp.97-107
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• 1970

The grand canonical ensemble partition function for the adsorbed phase of gases on solid surfaces is derived according to the transient state theory of significant liquid structure. The derived adsorption isotherms from the partition function for argon, nitrogen and benzene adsorbed on various adsorbents are in good agreement with the observed values. The surface pressure, the molar entropy, the molar internal energy and the molar heat of adsorption are calculated for benzene adsorbed on graphite. The molar entropy is minimum at near the pressure where a close packed monolayer is formed. The method of parameter determination is illustrated.

• Bulletin of the Korean Chemical Society
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• v.23 no.12
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• pp.1724-1728
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• 2002

The adsorption of proteins on the surface of glass slides is essential for the construction of protein chips. Here, we report that a Histidine (His)-tagged protein protein has been efficiently adsorbed on glass coated with nickel. A variety of nickel chloride-coated plates were prepared by the spin-coating method and adsorbed to the His-tagged protein. When the protein was adsorbed onto the surface of a variety of nickel chloride-coated glass slides, the efficiency of protein adsorption was dependent upon the coating conditions such as nickel chloride concentration, the spin speed and the drying temperature. The slides appropriate for protein adsorption were obtained when the slides were coated with 11%(w/w) of $NiCl_2$ at the spin speed of 4000 rpm for 20 sec and then dried at higher than 40°C. The physical properties of their nickel chloride thin layer were characterized by scanning electron microscopy. x-ray diffraction and atomic force microscopy, finding that the nickel chloride particles were around 10 nm in diameter and uniformly crystallized at 101 faces. These results show that nickel chloride-coated slides prepared by the spin-coating method are utilizable for the construction of Histagged protein chips.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1543-1550
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• 2010

This work presents oxidation of formic acid on Bi-modified Pt nanoparticles of various sizes. The sizes of the studied Pt nanoparticles range from 1.5 to 5.6 nm (detailed in Rhee, C. K.; Kim, B.-J.; Ham, C.; Kim, Y.-J.; Song, K.; Kwon, K. Langmuir 2009, 25, 7140-7147), and the surfaces of the Pt nanoparticles are modified with irreversibly adsorbed Bi. The investigated coverages of Bi on the Pt nanoparticles are 0.12 and 0.25 as determined by coulometry of the oxidation of adsorbed hydrogen and Bi, and X-ray photoelectron spectroscopy. The cyclic voltammetric behavior of formic acid oxidation reveals that the adsorbed Bi enhances the catalytic activity of Pt nanoparticles by impeding a poison-forming dehydration path with a concomitant promotion of a dehydrogenation path. The chronoamperometric results indicate that elemental Bi and partially oxidized Bi are responsible for the catalytic enhancement, when the Bi coverages on Pt nanoparticles are 0.12 and 0.25, respectively. The size effect of Bi-modified Pt nanoparticles in formic acid oxidation is discussed in terms of specific activity (current per unit surface area) and mass activity (current per unit mass).

• Bulletin of the Korean Chemical Society
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• v.25 no.12
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• pp.1817-1821
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• 2004

Fourier transform Raman spectra of methyl red adsorbed on untreated and pretreated ${\gamma}$-alumina and silicaalumina calcined at 900 $^{\circ}C$ under 1 atm steam flowing were recorded. Spectral analysis shows that the active species adsorbed on ${\gamma}$-alumina was to be deprotonated methyl red, and on silica-alumina to be di-protonated. This indicates that ${\gamma}$-alumina adapted in this work holds Bronsted basicity, and silica-alumina Bronsted acidity. Raman intensities of methyl red on pretreated ${\gamma}$-alumina are about three times stronger than on untreated ${\gamma}$-alumina, while spectral features are unchanged. For silica-alumina, spectral features show modified vibrational characteristics upon surface hydroxylations generated from pretreatment. Consequently, the acidity loss for silica-alumina and the basicity gain for ${\gamma}$-alumina were observed by increasing the surface hydroxyl groups on the catalysts through pretreatment of the steam calcination.

• Journal of the Korean Chemical Society
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• v.37 no.4
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• pp.416-422
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• 1993

As a result of adsorbing phthalocyanine (metal free, ${\alpha}\;and\;{\beta}$-Cu) on zinc oxide in aqueous solution using nonionic surfactant, all of the added dye was adsorbed and Na salt of sulfonated phthalocyanine showed the Langmuir monolayer adsorption. To analyze the effect of adsorption on zinc oxide, photovoltage was measured using surface photovoltmeter. The high photovoltaic effect was observed at intrinsic wavelength of zinc oxide and wavelength of adsorbed phthalocyanine dye. Metal free phthalocyanine, ${\alpha}$-copper phthalocyanine and ${\beta}$-copper phthalocyanine showed the highest photovoltaic effect when the percentage of coverage (${\theta}_{BET}$) for zinc oxide is about 80, while sulfonated phthalocyanine showed the highest photovoltaic effect when the percentage of coverage for zinc oxide is about 30.

• Bulletin of the Korean Chemical Society
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• v.24 no.5
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• pp.633-637
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• 2003

We have studied the surface-enhanced Raman spectroscopy (SERS) spectrum of quinomethionate (6-methyl-1,3-dithiolo[4,5-b]quinoxalin-2-one), which is an insecticide or fungicide used on vegetables and wheat. We observed no signals in the ordinary Raman spectra of solid-state quinomethionate, but when it was adsorbed on a colloidal silver surface, strong vibrational signals were obtained at a very low concentration. The SERS spectra were obtained by silver colloids prepared by the Creighton et al. method. The influence of pH and the aggregation inductors ($Cl^-,\;Br^-,\;I^-,\;F^-$) on the adsorption mechanism was investigated. Two different adsorption mechanisms were deduced, depending on the experimental conditions: The one N atom or two N atoms are chemisorbed on an Ag surface. An important contribution of the chemical mechanism was inferred when the one N atom was perpendicularly adsorbed on a surface. It is possible that quinomethionate can be detected to about $10^{-5}$ M.

• Membrane and Water Treatment
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• v.5 no.3
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• pp.171-182
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• 2014

Organic compounds are adsorbed on RO/NF membranes, and the adsorption may influence the rejection of organic compounds by the membranes. Because almost RO/NF membranes are composite membranes, the results obtained by adsorption experiment with using membrane pieces are unable to avoid the influence by the support membrane. In this work, the interaction between membrane polymer and organic solutes was examined by an inverse HPLC methodology. Poly (m-phenylenetrimesoylate), the constituent of skin layer of RO/NF membranes, was coated on silica gel particles and used as a stationary phase for HPLC. When water was used as a mobile phase, almost hydrophilic aliphatic compounds were not effectively adsorbed on the stationary phase, although hydrophobic compounds were slightly adsorbed. The results indicated that the hydrophilic aliphatic compounds are useful probe solutes to examine the molecular sieving effect of a membrane. When water was used as a mobile phase, the aromatic compounds were strongly retained, and therefore $CH_3CN/H_2O$ (30/70) was used as a mobile phase. It was revealed that the adsorption of aromatic compounds was controlled by stacking between solute and polymer and was hindered by non-planar structure and substituents.