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        검색결과 25

        4.
        2018.05 KCI 등재 서비스 종료(열람 제한)
        The adsorption characteristics of Cu ions were studied using the zeolite Na-A synthesized from Jeju volcanic rocks. The effects of various operating parameters such as initial concentration of Cu ions, contact time, solution pH, and solution temperature were investigated in batch experiments. The adsorption of Cu ions by Na-A zeolite was fitted well by pseudo-second-order kinetics and the Langmuir isotherm model. The maximum adsorption capacity determined using the Langmuir isotherm model was 152.95 mg/g. In addition, the adsorption of Cu ions by zeolite Na-A was primarily controlled by particle diffusion model in comparison with the film diffusion model. As the temperature increased from 303 K to 323 K, ΔG˚ decreased from -2.22 kJ/mol to –3.41 kJ/mol, indicating that the adsorption of Cu ions by Na-A zeolite is spontaneous process.
        5.
        2017.05 KCI 등재 서비스 종료(열람 제한)
        The removal characteristics of 2,4-dinitrophenol (2,4-DNP) from an aqueous solution by commercial Wood-based Activated Carbon (WAC) have been studied. The effects of various experimental parameters were investigated using a batch adsorption technique. The adsorption capacity of 2,4-DNP by WAC increased with a decrease in the dosage and particle size of WAC, temperature and the initial pH of the solution, and increased with an increase in the initial concentration of the solution. The adsorption equilibrium data were best described by the Redlich-Peterson isotherm model. The maximum adsorption capacities of 2,4-DNP by WAC were 573.07 mg/g at 293 K, 500.00 mg/g at 313 K, and 476.19 mg/g at 333 K, decreasing with increasing temperature. The kinetic data were well fitted to the pseudo-second-order model, and the results of the intra-particle diffusion model suggested that the adsorption process was mainly controlled by particle diffusion. The thermodynamic analysis indicated that the adsorption of 2,4-DNP by WAC was an endothermic and spontaneous process.
        6.
        2008.03 KCI 등재 서비스 종료(열람 제한)
        In order to develope an efficient way for the synthesis of highly pure 1,4-sorbitan solution from sorbitol, some experimental studies were performed. The reaction showed first order reaction with activation energy of 118.3 KJ/mol. Color of the product solutions changed to brown with reaction temperature and reaction time. The equilibrium contents of 1,4-sorbitan increased with decrease in reaction pressure, but the content of major impurity, sorbide, showed maximum about 550 torr vacuum with H3PO4 catalyst. The reasonable catalyst configuration was 0.26 wt% PTSA and 1 wt% H3PO2 and optimum reaction temperature and pressure range was 110~120℃ and 700~720 torr vacuum, respectively. At optimum reaction conditions, we could obtain white product solutions of highly pure 1,4-sorbitan with sorbide less than 10 wt%. This white product solution is advantageous for preparation of high quality span, anti-fogging agent.
        7.
        2007.08 KCI 등재 서비스 종료(열람 제한)
        For the purpose of development of an environmentally friendly aqueous cleanser, some experimental researches on emulsification of D-limonene were performed. OA series surfactants with different molecular weight were adapted as an emulsifier for preparation of O/W emulsion. Cleaning power of aqueous cleanser was measured by a dipping method adapting abietic acid(AA) as a solubilizate. Besides, drop size and drop size distribution, contact angle and storage stability of the aqueous cleansers were also measured and relationships among them were examined. Decrease in molecular weight of surfactant induced small drop size and contact angle, resulting in high cleaning power of aqueous cleanser. Aqueous cleanser consisted of 3wt.% OA300 and 30wt.% D-limonene showed the highest cleaning power, but displayed unfortunately with low storage stability. The storage stability of the aqueous cleanser with OA300 was significantly enhanced by addition of 0.5wt.% OA600 at the expanse of decrease in cleaning power.
        8.
        2006.06 KCI 등재 서비스 종료(열람 제한)
        SIS triblock copolymers, one of the major raw materials of oil gelling agent, were synthesized by living anionic polymerization and the resultant copolymers formed with various shapes and sizes were used to examine their oil gelling capacities. Coupling method was adapted to form final triblock products from diblock living polymers. Prior to polymerization, the impurities in monomers and solvents were throughly removed by killing technique. We experimentally investigated the effects of operating parameters of synthesis and forming of SIS triblock copolymers on oil gelling capacity. The photocatalytic decomposition of SIS triblock copolymer under ultraviolet circumstance was also investigated and it is found that the addition of P-25 enhances the photocatalytic decomposition.
        9.
        2004.12 KCI 등재 서비스 종료(열람 제한)
        The starch-filled waterborne acrylate (SWAC) films were prepared. The structures and properties of SWAC films were investigated by infrared spectroscopy, thermogravimetric analysis, and strength test. The biodegradability of SWAC film was also studied by determination of reduced sugar products after enzymatic hydrolysis. The surface morphology of the SWAC film was investigated by scanning electron microscopy (SEM). The results showed that the tensile strength and elongation of SWAC film decreased with the increase of starch content. The SWAC film showed significantly higher water absorbed content than waterbonre acrylate film. The biodegradability of SWAC film increased as the content of starch increased. The biodegradation of starch in SWAC film by α-amylase was about 77% of that of pure starch.
        10.
        2004.10 KCI 등재 서비스 종료(열람 제한)
        Waterborne fluorinated acrylate copolymer (WFAC) for surface modification of textile was synthesized from perfluoroalkyl ethyl acrylate, octadecyl acrylate, glycidyl methacrylate, surfactant and 3,3 methyl-methoxy butanol. The structures of the synthesized WFAC were determinated by FT-IR and 19F-NMR analysis. The thermal stability investigated with DSC and TGA was decreased with increasing the content of fluorinated acrylate in the copolymer. However, the particle sizes of WFAC were increased with increasing the content of fluorinated acrylate in the copolymer. The surface energies calculated by contact angles of WFAC were in the range of 29.80~13.41 dyne/cm. On the observing SEM of the textile surface treated with WFAC, the textile was swollen and compacted with increasing the concentration of water repellency agent. WFAC synthesized in this study showed a good water repellency.
        11.
        2004.09 KCI 등재 서비스 종료(열람 제한)
        The biodegradability of vinyl acetate acrylate resin and corn starch blend was studied by determination of the reduced sugars produced after enzymatic hydrolysis. The starch hydrolysis reaction by α-amylase was achieved within 5 minutes. Optimal ranges of temperature and pH for the starch hydrolysis by α-amylase were around 80 oC and 6.5-7.2, respectively. The biodegradability of the starch-filled acrylate films increased as the content of starch increased. The biodegradation of starch in the starch-filled acrylate film by α-amylase was about 48.6% of that of pure starch. This value of biodegradable starch-filled acrylate film gave a good result with enzymatic shortcut test. The surface morphologies of the starch-filled acrylate film after enzymatic hydrolysis were investigated by scanning electron microscopy (SEM).
        12.
        2004.03 KCI 등재 서비스 종료(열람 제한)
        An experimental study on the preparation of monolithic porous polymers by environmentally friend process in supercritical carbon dioxide has been carried out. Polymerization mixture composed of a cross-linking monomer, initiator and functional co-polymer was charged in the reactor with sapphire window. After the system was purged with a flow of CO2 for 15 min, the reactor was pressurized with liquid CO2 up to 100 bars. The reactor was isolated from and placed back to the system via quick connector for shaking until the mixture had become fully homogeneous. The reactor was then heated and pressurized to the required reaction conditions and left overnight. After cooling and CO2 evacuation, the polymer was removed from the reactor as dry, white, continuous monoliths. The effect of experimental conditions on the physical properties of porous polymer was systematically examined, and it was found that monomer content had a major effect on the physical properties of the polymers.
        13.
        2003.09 KCI 등재 서비스 종료(열람 제한)
        Adsorption of phosphate, sulfate, and copper ion to goethite was investigated. Goethite was prepared in the alkaline solution. In the single adsorbate systems, the final equilibrium plateau reached within 20 min. The adsorption isotherms of the individual ions could be well described by the Langmuir equation. The maximum adsorption capacities (qmax) were calculated as 0.483 mmol/g and 0.239 mmol/g at pH 3 for phosphate and sulfate ion, and 0.117 mmol/g at pH 6 for copper ion, respectively. In competitive adsorption system with phosphate and sulfate, phosphate ion was a stronger competitor for adsorption on goethite than sulfate ion, which was consistent with higher affinity of phosphate ion for the surface compared to sulfate ion. The existence of sulfate ion enhanced the adsorption of copper ion but the adsorption of sulfate was inhibited when copper ion was present.
        14.
        2003.09 KCI 등재 서비스 종료(열람 제한)
        For the purpose of surveying any possibility of anchoring titanium dioxide on activated carbons to promote their activities as catalysts and/or adsorbents, two activated carbons were oxidized with ammonium peroxydisulfate and followed by anchoring titanium dioxide. The anchoring of titanium dioxide on the oxidized activated carbons were performed via the adsorption of tetrabutyltitanate, hydrolysis with deionized water, and calcination. The effect of oxidizing and anchoring treatment on the surface element composition, surface area, and pore texture were analyzed by XPS, BET and TPD. The oxidation of activated carbons with ammonium peroxydisulfate introduced carboxyl groups on the surface of activated carbons and these carboxyl groups promoted the anchoring of titanium oxide on the activated carbons. However, the treatments affected the surface area and the porosity of activated carbons.
        15.
        2003.07 KCI 등재 서비스 종료(열람 제한)
        The photodegradations of pyrene, chrysene and benzo[a]pyrene that were similar in structure among polycyclic aromatic hydrocarbons (PAHs) were investigated with a low-pressure mercury lamp(the wavelength of 253.7 nm and UV output of 1.35x10-3 J/s). The optimum concentrations of TiO2 and H2O2 on the photodegradation of pyrene, chrysene and benzo[a]pyrene were 1 g/L and 1.5 x 10-3 M, respectively. By these optimum concentrations, their rates increased with increasing the concentration of TiO2 and H2O2 because the amounts of OH radical formed increased, but for the higher concentrations than the optimum, their rates decreased with increasing those concentrations because the white turbidity phenomena occurs in case of TiO2 and H2O2 acts as an OH radical inhibitor. The photodegradation rates among the photodegradation processes such as UV, UV/TiO2, UV/H2O2, and UV/H2O2/TiO2 decreased in the following sequences: UV/H2O2/TiO2> UV/H2O2> UV/TiO2> UV.
        16.
        2003.06 KCI 등재 서비스 종료(열람 제한)
        A recycling process for the waste FRP from boats was developed. The recycling process is composed of decomposition of waste FRP with propylene glycol and synthesis of recycled unsaturated polyester resin from the decomposed liquid material. Prior to the decomposition, waste FRP was cut into 2cm x 5cm segments and mechanical impact was applied by press roller to give gaps between cumulated laminates. Propylene glycol effectively decomposed the waste FRP segments and glass fibers were easily separated from decomposed liquid material. Recycled unsaturated polyester resin could be made from the decomposed liquid material by reaction with maleic anhydride and phthalic anhydride.
        17.
        2002.06 KCI 등재 서비스 종료(열람 제한)
        Photocatalytic degradation of phenol was carried out with UV-illuminated TiO2- SiO2 in aqueous suspension. TiO2-SiO2 catalysts were prepared by sol-gel method from the titanium isopropoxide and tetraethylorthosilicate at different Ti/Si ratio and some commercial TiO2 catalysts were used as purchased. All catalysts were characterized by X-ray Diffraction(XRD) and BET surface area analyzer. The effect of reaction conditions, such as initial concentration of phenol, reaction temperature and catalyst weight on the photocatalytic activity was studied. In addition, TiO2-SiO2(49:1) prepared by sol-gel method showed higher activity than commercial TiO2 catalysts on the photocatalytic degradation of phenol. The addition of SiO2 into TiO2 hepled to increase the thermal stability of titania which suppressed the formation of anatase into rutile. The photocatalytic degradation of phenol showed pseudo-1st order reaction and the degradation rate increases with decreasing initial phenol concentration.
        18.
        2001.12 KCI 등재 서비스 종료(열람 제한)
        Adsorption characteristics of triadimefon and diniconazole(pesticide) by natural zeolite(CLIN) and several synthetic zeolites were investigated. The synthetic zeolites used in this study were as follows: Faujasite synthesized from coal fly ash(FAUF); Zeolite synthesized from the mixture of FAU and Na-Pl synthesized from the ratio of Cheju scoria 6 to coal fly ash 4 by weight((FAU + Na-Pl)SF); Waste fluid catalytic cracking catalyst(FCCw). The distribution coefficient, KD and Freundlich constant, KF decreased in the following sequence : FCCW>FAUF>(FAU+Na-Pl)SF > CLIN among the zeolites. The distribution coefficient and the adsorption capacity of (FAU + Na-Pl)SF for pesticides were 4.4 and 2.6 times higher for triamefon, and 2.0 and 2.4 times higher for diniconazole than those of CLIN, respectively.
        19.
        2001.12 KCI 등재 서비스 종료(열람 제한)
        For the purpose of developing a new process for the elimination of oil components from oily waste water, experimental researches using oil gelling agent were performed. The process is composed of three units, that is, decantator, gelling column and adsorption column. l0g of gelling agent in the gelling column could effectively absorb 15.65g of oil from ship washing waste water and 16.93g of oil from steel industry waste water. COD in waste waters dramatically diminished not in the gelling column but in the adsorption column. The gelling is hindered by other organic components in waste water, and the optimum space time for the gelling column is 20min. lg of gelling agent absorbed 3.7-4.0g of oil from waste waters with 25 min in the batch operation.
        20.
        2001.10 KCI 등재 서비스 종료(열람 제한)
        The characteristics of precipitation separation and solvent extraction separation of magnesium from the waste bittern were studied experimentally. In the result of precipitation separation, the size of magnesium hydroxide precipitated was not affected on pH, but decreased with increasing the precipitation temperature. The purity of magnesium oxide precipitated was increased with pH beyond pH 11. From the solvent extraction separation, the equilibrium extraction ratio of magnesium was increased with pH and temperature of extraction phase, the concentration of stripping phase, and with decreasing pH of stripping phase. The extractant of Aliquat 336 and Acid 810 mixture was more effective than that of DCH18C6 and D2EHPA mixture in the extraction separation of magnesium.
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