• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.628-633
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• 2013

Carbon black was surface-modified to prepare styrene-based suspension polymerized toner with excellent carbon black dispersibility inside toner particles. Carbon black was oxidized first to introduce hydroxyl groups on the surfaces, then esterification between the hydroxyl groups and carboxyl groups of organic acids (oleic acid, palmitic acid, acrylic acid) was followed to obtain organically surface-modified carbon black. The surface-modification of carbon black was confirmed by FTIR. Apparent carbon black dispersibility in the monomer mixture of the binder resin was tested and the particle size of dispersed carbon black was measured by particle size analyzer. Optical micrographs showed that carbon black dispersibility inside toner particles was improved considerably when the carbon black surfacemodified with oleic acid was used. The polymerized toner prepared with the carbon black surface-modified with oleic acid showed ideal particle size and size distribution as a toner.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.1
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• pp.73-79
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• 2001

Stricter environmental demands have increased the need to replace conventional C/D bleaching sequence by chlorine-free sequence. Permanganate is well known as a powerful oxidant and have been used industrially in variable fields. However, it has considered to be difficult to use permanganate as a bleaching reagent because of its strong oxidative effect decreasing the viscosity of pulps extremely. We have tried to use permanganate as a bleaching reagent for KP under the mild condition and it was clear that pernanganate oxidized lignin remained in pulps selectively and increased pulp brightness decreasing K number of pulps with small degradation of cellulose. We have employed the neutral condition in the permanganate bleaching process in this study. In this case, permanganate was converted to manganese dioxide after bleaching reaction. The manganese dioxide is remained in the treated pulp fibers because of its insolublity in water. So it was required to reduction the manganese oxide to manganese ion by using reductants with acid. In this paper, we proposed to use oxalic acid as a reducing reagent converting manganese oxide to manganese ion after bleaching reaction. Oxalic acid plays the role as a reductant and a acid, so post-treatment after bleaching became to be easy by using oxalic acid. On the study using lignin model compounds, it was clear that permaganate react with phenols firstly, after that oxalic acid reduce the manganese oxide to manganese ion in the mixture of permanganate, phenols and oxalic acid. Several lignin model compounds ($\textit{p}$-hydroxybenzaldehyde, vanillin, syringaldehyde, veratraldehyde) are selected to elucidate the effect of substituents on reaction rate and its mechanism with permanganate including oxalic acid in this study. Except for veratraldehyde, the rate of oxidative degradation of phenolic compounds by permanganate with oxalic acid are higher than neutral condition. Especially, the degradation rate of $\textit{p}$-hydroxybenzaldehyde are strongly dependent on pH of reaction mixture. On the other hand, the degradation rate of veratraldehyde are decreased with decreasing pH and main degradation product is veratric acid. This result indicate that pH of bleaching liquor should be kept over 2 to degrade of non-phenolic lignin in the pulps effectively in permanganate bleaching.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.3
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• pp.330-336
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• 2005

The ozone injection method was proposed to improve the catalytic process for the removal of nitrogen oxides ($NO_x$). Nitric oxide (NO) in the exhaust gas was first oxidized to nitrogen dioxide ($NO_2$) by ozone produced by dielectric barrier discharge, and then the exhaust gas containing the mixture of NO and $NO_2$ was directed to the catalytic reactor where both NO and $NO_2$ were reduced to $N_2$ in the presence of ammonia as the reducing agent. A commercially available $V_2O_5-WO_3/TiO_2$ catalyst was used as the catalytic reactor. The $NO_2$ content in the mixture of NO and $NO_2$ was changed by the amount of ozone added the exhaust gas. The effect of reaction temperature, initial $NO_x$ concentration, feed gas flow rate, and ammonia concentration on the removal of $NO_x$ at various $NO_2$ contents was examined and discussed. The increase in the content of $NO_2$ by the ozone injection remarkably improved the performance of the catalytic reactor, especially at low temperatures. The present ozone injection method appears to be promising for the improvement of the catalytic reduction of $NO_x$.

• Korean Chemical Engineering Research
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• v.44 no.1
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• pp.65-72
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• 2006

Recent technical advances in the biorecognition engineering and the microparticle fabrication may enable us to develop the single step purification using magnetic particle, because of its simplicity, efficacy, ease of automation, and process economics. In this study, we used commercial magnetic particles from Seradyn, Inc. (Indianapolis, USA). It was ca. 2.8 micron in diameter, consisted of polystyrene core and magnetite coating, and its surface had carboxyl groups. The model, capture protein was IgG and anti-IgG was used as the ligand molecule. We studied the different surfaces ('nude', ester-activated, and anti-IgG coated) for their biorecognition of IgG. At a high pH condition, we could reduce non-specific binding. Also anti-IgG immobilized magnetic particle could capture IgG more selectively. We attempted 'oriented immobilization' of anti-IgG, in which the polysaccharides moiety near the C-terminus was selectively oxidized and linked to the hydrazine-coated MP, to improve the efficacy of biorecognitive binding. Using this method, the IgG capturing ability was improved by ca. 2 fold. From the binary mixture of the IgG-insulin, IgG could be more selectively captured. In summary, the oriented immobilization of oxidized anti-IgG proved to be as effective as the streptavidin-biotin system and yet simpler and cost-effective. This immobilization method can find its applications in protein biochips and biotargeting.

• Journal of Life Science
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• v.10 no.3
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• pp.254-261
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• 2000

In order to observe the bioactivity of ovariectomized rats, ovariectomized group (Ovx), nonovariectomized group (Sham), ovariectomized Vitamin C-treat group (Ovx+Vit C), ovariectomized Vitamin E-treat group (Ovx+Vit E) and ovariectomized Vitamin C+Vitamin E-treat group(Ovx+Vit C+E) were made. Lipidperoxides of liver and kidney, serum total cholesterol and HDL-cholesterol were investigate as follows. Lipidperoxides of liver and kidney in Ovx group were 1.78 times and 1.61 times increased compared to Sham group respectively. But, they were significantly decreased in Ovx+Vit C group, Ovx+Vit E group, Ovx+Vit C+E group compared to Ovx group. Serum total cholesterol in Ovx group was increased 2.57 times compared to Sham group. Injections of each substance such as ascorbate, tocopherol, mixture (C+E) make data of Cholesterol become low. When especially Vit C is injected, the data of cholesterol lowed by about 94%. Serum HDL-cholesterol in Ovx group decreased 36.7% compared to Sham group. And as the result of the measurement of SOD, Catalase, and GPx which are antioxidant enzyme, SOD and Catalase activities in Ovx group much higher than in Sham group. Based on the results, it is supposed that more produced free radicals increased antioxidant enzyme. And it is also thought that vitamin can inhibit aging by reducing antioxidant enzyme.

• Journal of the Mineralogical Society of Korea
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• v.17 no.1
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• pp.37-47
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• 2004

Sulfates such as alunite and schwertmannite formed under oxidation condition play a important role in geochemical processes taken place at waste dumps and a creek from Dalseong mine, Daegu. Water chemistry shows pH decreases from upstream toward downstream creek, mainly due to formation of schwertmannite that is the most abundant phase along the creek. The removal of Al from the creek is preferentially attributed to formation of Al-bearing minerals and Al-sulphates. Among them, alunite is the most important Al-sink phase that occurs at higher pH than $pK_1$, Al hydrolysis constant. With high saturation index, alunite formed at the creek has a spherical form, commonly associated with schwertmannite. Secondary minerals formed on the surface of altered or weathered surfaces of heavy metals from the wasted dump that underwent severe oxidation, where alunite has characteristic habits which are spheric, radiating, and botrytis-like aggregates. Natroalunite occurs in association with alunite, or as mixtures of both of them. Because the pH decreases with distance due to formation of schwertmannite, although total contents of dissolved ions slowly lessen at least in the AMD, it is expected that the minerals precipitated at the creek can be exposed to subsequent dissolution, which may induce possible environmental problems.

• Journal of the Korean Chemical Society
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• v.33 no.6
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• pp.633-643
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• 1989

The R$Rh_2(ap)_4$(2,2-trans) isomer (ap = 2-anilinopyridinate), which has two anilino nitrogens and two pyridyl nitrogens bound to each rhodium ion trans to their own kind, shows activation towards the one electron reduction of dioxygen at -0.40 V vs SCE. The ESR spectrum taken at 123 K proves the formation of a $[Rh_2(ap)_4(O_2)]$ ion with oxygen axially bound to one rhodium ion and the complex is at a RhⅡ2 oxidation state. The complex will form [$Rh_2(ap)_4(O_2)(CH_3CN)]^-$ in presence of $CH_3CN/CH_2Cl_2$ mixture without breaking the Rh-$O_2^-$ bond. When oxidized at -0.25 and 0.55 V, $[Rh_2(ap)_4(O_2)]$ will undergo two one electron oxidations to form $Rh_2(ap)_4(O_2)[Rh_2(ap)_4(O_2)]^+$. Both species have an axially bound superoxide ion but the former is at $Rh^{II}Rh^{III }$and the later at $Rh^{III}_2$ oxidation states. The ESR spetra and $CH_3CN$ addition study, on the other hand, show that the later complex is better described as $[Rh_{II}Rh^{III}(ap)_4(O_2)]^+$ with the odd electron localized on rhodium ion and the complex has an axially coordinated molecular oxygen. The electrochemical and ESR studies also show that the degree of dioxygen activation is a function of electrochemical redox potential.

• Journal of the Korean Ceramic Society
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• v.39 no.7
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• pp.657-662
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• 2002

The reduced ferrites, reduced NiF $e_2$ $O_4$ and CuF $e_2$ $O_4$, by C $H_4$ were applied to $CO_2$ decomposition to avoid the greenhouse effects. At the reduction reaction above $700^{\circ}C$, $H_2$ and CO were generated by partial oxidation of C $H_4$ After the reduction reaction up to 80$0^{\circ}C$, the spinel structure ferrites changed to mixture of the oxygen deficient iron oxide (Fe $O_{(1-{\delta})}$(0$\leq$$\delta$$\leq$1)) and the metallic Ni or Cu. The rate and quantity of $CO_2$ decomposition with reduced CuF $e_2$ $O_4$ were larger than those with reduced NiFe $O_4$. The $CO_2$ gas was decomposed by oxidation of the oxygen deficient iron oxide. The metallic Cu and Ni were not oxidized and remained in a metallic state up to 80$0^{\circ}C$. The $CO_2$ decomposition reaction with the reduced ferrite by C $H_4$ gas is excellent process preparing useful gas such as $H_2$and CO and decomposing $CO_2$ gas.

• Resources Recycling
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• v.18 no.6
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• pp.30-37
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• 2009

Silica sol was prepared from the mixture of sodium silicate solution and oxidized silicate solution in which sodium had been removed by sol-gel process. The properties of sodium silicate solution and silicate solution thus prepared were characterized by yellow silicomolydate method. Moreover, the formation and growth of silica sol from sodium silicate solution was investigated. Sodium silicate solution with 2% of $SiO_2$ contains 95% of reactive silicate, and 50% of reactive silicate participates sol-gel reaction. From the results of FT-IR analysis, it was found that the intensity of silanol bond decreased and the intensity of siloxane bond increased with increasing reaction temperature. Zeta potential of silica sol prepared at each condition was -40~-60 mV and it could be known that silica sol in this study was well dispersed. The silica sol with 5~10 nm size could be prepared by heating the mixed solution of sodium silicate and silicate solution. And the silica sol grew into about 20 nm as silicate solution was added to silica sol solution.

• The Korean Journal of Physiology
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• v.2 no.2
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• pp.93-99
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• 1968

The Present study attempted to analyze the fate of CO diffused into the circulating blood through the alveoli. Dogs were induced to CO poisoning by rebreathing CO gas mixture contained in Krog's spirometer, by closed circuit method, for 60 minutes. The spirometer was filled initially with 282 ml of CO and 20 liters of air and oxygen, so the composition of gases were arranged as 1.4% in CO and 50% in $O_2$ at the begining of the rebreathing. Oxygen was added corresponding to the utilization of $O_2$ by the animal in proceeding of the experiment. At 60th minutes of CO rebreathing, the concentration of CO in arterial blood and in mixed venous blood were analysed and compared with each other after the CO contents were corrected with the hematocrit measured in the arterial and mixed venous blood. The distribution of CO gas to other tissues was estimated by the analysis of CO diffused into the cystic bile and into the peritoneal gas pocket which was formed by injection of 300 ml air into the peritoneal cavity prior to the CO gas rebreathing. The blood volume was measured by dilution method using $^{51}Chromium$ tagged red cells. CO amount vanished in the animal body was calculated by subtraction of total CO content in blood stream and the CO remained in closed circuit breathing system from the CO amount given to the breathing system at the begining of the experiment. Results obtained are summarized as follows: 1. The content of CO corrected by the hematocrit value was slightly less in mixed venous blood than in arterial blood. The amount of CO diffused into the cystic bile and into the peritoneal cavity was averaged to 0.1% and 0.4% of the CO amount in 100 ml of blood, respectively. 2. For 60 minutes of CO rebreathing, CO-hemoglobin saturation reached about 77% at the 60th minutes, CO amount vanished in the experimental animal averaged 36.1 ml/dog/hr., or 21% of the total CO volume in the blood stream. The average vanishing rate of CO during 60 minutes of CO rebreathing per kg of body weight was 2.71 ml/hr. Production of CO measured in ten dogs under hypoxic condition averaged 0.023 ml/kg/hr. The major part of the CO vanished in the dogs seemed to be oxidized to $CO_2$ by various tissues of the animal. The conclusion might be delivered as such oxidation of CO to $CO_2$ by animal tissues can play a role in part of the process of recovery and protection of animal from CO-poisoning.