• Applied Chemistry for Engineering
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• v.28 no.3
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• pp.286-289
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• 2017

Synthesis of zeolite 4A was carried out to optimize the nanoparticle synthesis process using statistical experimental design method. The zeolite 4A was synthesized by controlling the concentration of the silicon precursor, sodium metasilicate (SMS), and characterized by XRD, SEM and nitrogen adsorption. In particular, the property of zeolite 4A can be determined by XRD analysis. Using the general factor analysis in the design of experiments, we analyzed main effects and interactions according to the reactor, reaction temperature and reaction time. The optimum reaction condition for the synthesis of zeolite 4A crystallinity was using an autoclave for 3 hours at $110^{\circ}C$. Furthermore, the optimal synthesis conditions of zeolite 4A with various crystallinity using Ludox as a silicon precursor were presented of what using both the surface and contour plot.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.927-933
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• 1997

The effects of carbon black on the electrodes performance and on the structure of the catalyst layer in Raney nickel hydrogen electrodes for alkaline fuel cells were investigated by using electrochemical and nitrogen adsorption methods. The optimum content of carbon black in the catalyst layer of Raney nickel hydrogen electrode was 2wt%. The limiting current density was increased by the addition of carbon black due to the enlargement of gas-liquid interface area. The rate determining step at the limiting current density was supposed to be a step where hydrogen dissolves at gas-liquid interfaces.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.79-83
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• 2006

The first quantitative structure determination has been obtained for Cu(100)/glycine $(NH_2CH_3COOH)$. The molecule is adsorbed on the surface via two functional groups: the nitrogen of the amino group and one or both two oxygen atoms of the carboxylate group are bonded in near atop site. The Cu-N is tilted $5^{\circ}\pm4^{\circ}C$, away from the surface normal whilst the Cu-O is tilted by $9^{\circ}\pm2^{\circ}C$. The chemical bonding lengths are determined with $2.05\pm0.02\;{\AA}$ for both Cu-N and Cu-O. This bonding geometry is similar to that of glycine on Cu(110). A reanalysis of O Is from the Cu(110)$(2\times3)$pg-glycine show two oxygen atoms are inequivalent, with one being offset $0.29\;{\AA}$ more than the other.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.04a
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• pp.99-101
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• 1998

1. Introduction : The conventional grafting polymerization technique requires chemically reactive groups on the surface as well as on the polymer chains. For this reason, a series of prefunctionalization steps are necessary for covalent grafting. The surface prefunctionalizational technique for grafting can be used to ionization radiation, UV, plasma, ion beam or chemical initiators. Of these techniques, radiation method is one of the useful methods because of uniform and rapid creation of active radical sites without catalytic contamination in grafted samples. If the diffusion of monomer into polymer is large enough to come to the inside of polymer substrate, a homogeneous and uniform grafting reaction can be carried out throughout the whole polymer substrate. Radiation-induced grafting method may attach specific functional moieties to a polymeric substrate, such as preirradiation and simultaneous irradiation. The former is irradiated at backbone polymer in vacuum or nitrogen gas and air, and then subsequent monomer grafting by trapped or peroxy radicals, while the latter is irradiated at backbone polymer in the presence of the monomer. Therefore, radiation-induced polymerization can be used to modification of the chemical and physical properties of the polymeric materials and has attracted considerable interest because it imparts desirable properties such as blood compatibility. membrane quality, ion excahnge, dyeability, protein adsorption, and immobilization of bioactive materials. Synthesizing biocompatible materials by radiation method such as preirradiation or simultaneous irradiation has often used $\gamma$-rays to graft hydrophilic monomers onto hydrophobic polymer substrates. In this work, in attempt to produce surfaces that show low levels of anti-fouling of bovine serum albumin(BSA) solutions, hydroxyethyl methacrylate(HEMA) was grafted polypropylene membrane surfaces by preirradiation technique. The anti-fouling effect of the polypropylene membrane after grafting was examined by permeation BSA solution.

• Journal of the Korean Chemical Society
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• v.16 no.6
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• pp.341-348
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• 1972

The significance of the curvature dependency correction of surface tension is studied in calculating the pore volume distribution of porous adsorbent from nitrogen adsorption isotherm. That is, Kelvin radii are calculated with curvature dependent surface tension values calculated by Chang et al, and then with these Kelvin radii, pore volume distributions of three porous adsorbents, silica alumina (steam deactivated), silica gel (Davidson 59), and silica gel (Mallinc-krodt Standard Luminescent), are calculated. The results are compared with those obtained by the previous method in which surface tension is taken as constant and also with the others. obtained by the modelless method proposed by Brunauer et al. The maximum point of the distribution curve shift to the larger pore radius, when the curvature dependency is considered. Furthermore, the relative pressure at which capillary condensation commences is by far the lower than that accepted previously. This effect becomes significant as the pore radius approaches to the micropore range.

• Journal of the Korean Chemical Society
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• v.37 no.10
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• pp.867-873
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• 1993

Influences of crystallization time and $H_2O/Al_2O_3$ ratio of the reaction mixtures on the synthesis of AlPO$_4$-5 molecular sieve have been studied by X-ray powder diffraction, nitrogen adsorption, scanning electron microscope (SEM), and solid state $^{27}$Al magic angle spinning nuclear magnetic resonance (MAS NMR) techniques. The degree of crystallinity of AlPO$_4$-5 follows a sigmoid pattem as crystallization time increases. The induction period is shorter than 1 h when the crystallization process is carried out at 150$^{\circ}$C. The conversion of reactants to product, AlPO$_4$-5, can be clearly observed, and all of the determined physical properties change abruptly after about 2 h. It is found that increase in $H_2O/Al_2O_3$ ratio of the reaction mixtures not only changes the crystal morphology from aggregates to hexagonal single crystals, but also results in the formation of longer AlPO$_4$-5 crystals.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1279-1284
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• 2012

Silica supported $Cs_{2.5}H_{0.5}PMo_{12}O_{40}$ catalyst was prepared through sol-gel method with ethyl silicate-40 as silicon resource and characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, nitrogen adsorption-desorption and potentiometric titration methods. The $Cs_{2.5}H_{0.5}PMo_{12}O_{40}$ particles with Keggin-type structure well dispersed on the surface of silica, and the catalyst exhibited high surface area and acidity. The catalytic performance of the catalysts for benzene liquid-phase nitration was examined with 65% nitric acid as nitrating agent, and the effects of various parameters were tested, which including temperature, time and amount of catalyst, reactants ratio, especially the recycle of catalyst was emphasized. Benzene was effectively nitrated to mononitro-benzene with high conversion (95%) in optimized conditions. Most importantly, the supported catalyst was proved has excellent stability in the nitration progress, and there were no any other organic solvent and sulfuric acid were used in the reaction system, so the liquid-phase nitration of benzene that we developed was an eco-friendly and attractive alternative for the commercial technology.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.691-696
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• 2011

CTAB or CTAB-Nafion catalyst were successfully supported on siliceous hollow tubular MCM-41 which synthesized by hydrothermal method using CTAB as a single template or CTAB and Nafion-Na as mixed templates. The properties of two kinds of catalysts were characterized with XRD, SEM and adsorption and desorption isotherms of nitrogen and pore diameter distribution, respectively. Then they were applied to catalyze brominating reaction of 1,7-heptanediol, moreover the rate of brominating reaction with different catalysts was compared. The results showed that catalytic activities of CTAB/MCM-41 and CTAB-Nafion/MCM-41 are better than CTAB, and that of CTAB-Nafion/MCM-41 is the best because of its phase-transfer and strong acidity function. The two kinds of catalysts can be separated from the reactive products and recycled.

• Journal of the Korean Chemical Society
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• v.21 no.3
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• pp.204-209
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• 1977

The properties of the natural zeolite produced in Kuryongpo, Kyungsang-Bukdo, were investigated by X-ray diffraction analysis, chemical composition analysis, and nitrogen adsorption experiment. The quality of the acid treated natural zeolite as the catalyst for the disproportionation reaction of toluene was examined experimentally by observing the conversion in a microcatalytic reactor. The quantitative analysis and X-ray diffraction spectrum showed that the zeolite ore of Kuryongpo contained approximately 30 to 40 percent of mordenite structure. The surface area of the zeolite ore was $75m^2$/gm and increased to a maximum value of $320m^2$/gm after treatment with 2 N HCl solution. The catalytic activity for the toluene disproportionation reaction was maximum when the zeolite treated with 2 N HCl solution was used. The selectivity of xylene to benzene decreased with increasing degree of acid treatment.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.2
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• pp.192-200
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• 2016

A characteristics of microwave drying-gasification was analyzed for converting a dewatered sewage sludge generated a wastewater treatment plant. Gas (60%) was the largest component of the product of microwave gasification, followed by sludge char (33%) and tar (2%). The main components of the producer gas were hydrogen (33%) and carbon monoxide (40%), and there was some methane and hydrocarbons ($C_2H_4$, $C_2H_6$, $C_3H_8$). Larger nitrogen and smaller oxygen amounts were generated. Gravimetric tar generated $414g/m^3$. This means a total tar which is a heavy hydrocarbons from the volatile organic substance in the sewage sludge. Selected light tars were benzene, anthracene, naphthalene, pyrene, showing lower concentrations as 2.62, 0.37, 0.49, $0.28g/m^3$, respectively. Sludge char has larger meso pores which is a mean pore size of $50.85{\AA}$ and has high adsorptivity. An amount of adsorption was $228.71cm^3/g$, showing higher quantity than acommercial adsorbers. This indicates that the gas obtained from the microwave gasification of wet sewage sludge can be used as fuel, but the heavy tar in the gas must be treated. Sludge char can be used as a tar reduction adsorbent in the process, and then burns as a solid fuel.