• Journal of the Korean Chemical Society
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• v.66 no.2
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• pp.78-85
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• 2022

Natural white clay was treated with 6 M of H₂SO₄ and heated at 80℃ for 6 h under mechanical stirring and the resulting acid active clay was used as an adsorbent for the removal of Cs⁺ in water. The physicochemical changes of natural white clay and acid active clay were observed by X-ray Fluorescence Spectrometry (XRF), BET Surface Area Analyser and Energy Dispersive X-line Spectrometer (EDX). While activating natural white clay with acid, the part of Al₂O₃, CaO, MgO, SO₃ and Fe₂O₃ was dissolved firstly from the crystal lattice, which bring about the increase in the specific surface area and the pore volume as well as active sites. The specific surface area and the pore volume of acid active clay were roughly twice as high compared with natural white clay. The adsorption of Cs⁺ on acid active clay was increased rapidly within 1 min and reached equilibrium at 60 min. At 25 mg L^- of Cs⁺ concentration, 96.88% of adsorption capacity was accomplished by acid active clay. The adsorption data of Cs⁺ were fitted to the adsorption isotherm and kinetic models. It was found that Langmuir isotherm was described well to the adsorption behavior of Cs⁺ on acid active clay rather than Freundlich isotherm. For adsorption Cs⁺ on acid active clay, the Langmuir isotherm coefficients, Q, was found to be 10.52 mg g^-1. In acid active clay/water system, the pseudo-second-order kinetic model was more suitable for adsorption of Cs⁺ than the pseudo-first-order kinetic model owing to the higher correlation coefficient R² and the more proximity value of the experimental value q_e,exp and the calculated value q_e,cal. The overall results of study showed that acid active clay could be used as an efficient adsorbent for the removal of Cs⁺ from water.

• Korean Journal of Materials Research
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• v.9 no.5
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• pp.467-472
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• 1999

The isothermal cure behavior of diglycidyl ether of bisphenol A(DGEBA) 4,4'-methylene dianiline(MDA) system with various contents of neopentyl glycol(NPG) has been analyzed by differential scanning calorimetry(DSC). TO increase the cure rate of DGEBA/MDA system, NPG was introduced as an accelerator. Regardless of the NPG content, the shape of the conversion curves showed sigmoid indication that DGEBA/MDA/NPG system followed autocatalytic cure reaction. The cure reaction of DGEBA/MDA system increased with the increment of NPG content and it was due to the catalytic role of hydroxyl groups of NPG.

• Applied Chemistry for Engineering
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• v.18 no.1
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• pp.94-97
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• 2007

Carbon nanotubes and nanowires were prepared by methane pyrolysis over Pd(5)/SPK catalyst by changing oxygen molar ratio in a fixed bed flow reactor under atmospheric condition and also analyzed by SEM and TEM. When the $CH_4/O_2$ molar ratio was 1, carbons were not almost deposited on the catalyst bed support, but when it was 2, carbons were deposited as much as plugging reactor. TEM and SEM images for the deposited carbons showed a number of single-walled carbon nanotubes and carbon nanowires. The growth mechanism of carbon nanotubes produced on the catalyst surface was the tip growth mode. It should be played an important role in carbon nanotubes and nanowires produced on the catalyst bed support to formate the carbon growth velocity vectors and nuclei of ring structure of carbon nanowires. SPK carrier was $N_2$ isotherm of IV type with mesopores, and excellent in the thermal stability.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.4
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• pp.446-452
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• 2008

This study was conducted to research the biosorption characteristics using algae, Spirulina platensis, for the removal of Pb and Cu ions in wastewater. Both of free algal cell and immobilized algae by Ca-alginate were used as bioadsorbent, and experiment was proceed in batch reactor for Pb and Cu ions removal, respectively. In the biosorption of Pb and Cu ions by free Spirulina platensis cell, the adsorption equilibrium reached within 20 minute. The higher adsorbed amount of Pb and Cu was shown as increasing of initial concentration of Pb and Cu, and pH of solution, respectively, and the optimum pH was 4.5$\sim$5.0. Under the conditions of initial concentration of Pb or Cu are 200 mg/L, the maximum amounts of Pb and Cu adsorbed to the unit weight of Spirulina platensis were 86.43 and 57.02 mg/g, respectively, and these values were 1.94 and 1.48 times higher than those of activated carbon under same conditions, respectively. The biosorption kinetics of Pb and Cu ions by free Spirulina platensis cell fitted very well to the Freundlich and Langmuir isotherm. The maximum amount of Pb or Cu adsorbed to the unit mass of adsorbent by the Langmuir isotherm($q_{max}$) represented as 95.24 and 62.50 mg/g, respectively. The FT-IR results of free Spirulina platensis biomass showed that biomass has different functional groups and these functional groups are able to react with metal ions in aqueous solution. In the biosorption of Pb and Cu ions by Ca-alginate immobilized algae Spirulina platensis, the adsorption equilibrium reached within 40 min. and observed a little diffusion limitation differed from the free algal cell adsorption.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.442-448
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• 2012

The effects of zeolite-type catalysts addition on the thermal decomposition of the PP resin have been studied in a thermal analyzer, a Pyrolyser GC-mass, and a small batch reactor. The zeolite type catalysts tested were natural zeolite, used FCC catalyst, and ZSM-5. As the results of TGA experiments, the pyrolysis starting temperature for PP varied in the range of $330{\sim}360^{\circ}C$ according to the heating rate. Addition of the zeolite type catalysts in the PP resin increased the pyrolysis rate in the order of used FCC catalyst> natural zeolite> ZSM-5 > PP resin. Adding the used FCC catalyst in the PP reduced most effectively the pyrolysis finishing temperature. In the PY-G.C. mass experiments, addition of zeolite type catalysts decreased the molecular weight of pyrolyzed product. In the batch system experiments, the mixing of used FCC catalyst enhanced best the initial yield of fuel oil, but the final yield of fuel oil was 2% higher in the case of mixing of natural zeolite. Also in the carbon number analysis, used FCC catalyst was the most useful one in this experiments for fuel oil.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.30-32
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• 2012

본 연구에서는 Cu, Mn을 함침 시킨 상용 제올라이트13X 촉매에 CO 산화 전환 반응에 영향을 연구하였다. 촉매 제조는 담지량별로 Cu, Mn을 서로 다른 비율로 물리 혼합하여 상용 제올라이트에 담지하였다. 함침방법은 과잉용액 함침법을 사용하였고, 건조 후 공기분위기에서 소성하여 산화물 형태로 담지하였다. 기본적인 촉매 특성은 X-선 회절분석, 질소흡탈착 등온곡선을 이용하여 기공크기, 기공부피, 비표면적을 구하였으며, FT-IR, 주사현미경, $NH_3$-TPD/TPR, EDX로 특성을 분석하였다. 촉매 산화반응 실험은 고정층 반응기에서 수행하였으며, 외경1/4 inch(내경 4 mm)석영관에 촉매를 중진하고 Gas Chromatograph로 배출가스를 측정하여 Cu-Mn 제올라이트 촉매의 일산화탄소 산화반응을 연구하였다. 일산화탄소 농도, 온도 및 공간속도, Cu-Mn 함량 비율에 따른 산화반응 실험을 수행하여 최적 산화조건과 촉매를 도출하였다.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.495-500
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• 2009

Activated carbon was used as an adsorbent to capture benzene vapor from gaseous stream of nitrogen in a fixed-bed to obtain the breakthrough data. The deactivation model is used to analyze the adsorption kinetics of benzene vapor using the experimental breakthrough data. The experimental breakthrough data are fitted very well to the deactivation model than the adsorption isotherm models in the literature.

• Korean Journal of Materials Research
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• v.9 no.3
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• pp.327-332
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• 1999

The recovery activation energy, the order of reaction and the recovery rate constant were detemined by isochronal and isothermal annealing treatment to investigate the recovery behaviors of neutron irradiated Mn-Mo-Ni low alloy steels$(fluence: 2.3\times10^{19}ncm^{-2}, 553K, E\geq1.0 MeV)$. Vickers microhardness tests were conducted to trace the recovery behavior after heat treatments. The results were analyzed in terms of recovery stages, behavior of responsible defects and recovery kinetics. It was shown that recovery occurred through two annealing stages(stage I : 703-753K, stage n : 813-873K) with re$\infty$very activation energies of 2.5 eV and 2.93 eV for each stage I and n, respectively. From the comparison of unirradiated and irradiated isochronal anneal curves, a radiation anneal hardening(RAH) peak was identified at around 813K. Most of recovery have occurred during about 120 min irrespective of isothermal annealing temperatures of 743K and 833K. Recovery rate constants were determined to be $3.4\times10^{-4}min^{-1} and 7.1\times10^{-4}min^{-1}$ for stage I and II, respectively. The order of reaction was about 2 for both recovery stages. Comparing the obtained data with those of previously reported results on neutron irradiated Mn- Mo- Ni steels, the thermal recovery be­havior of the present material seems to occur by the dissociation of point defect clusters formed during irradiation, and by the recombination process of self-interstitials and vacancies from dissociated vacancy clusters.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.16-19
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• 2010

Devolatilization characteristics of municipal wood waste were measured by using an isothermal thermogravimetric analyzer(TGA) and discussed. Volatile matter was mainly released at temperatures between $250^{\circ}C$ and $350^{\circ}C$. The volatile content increased with an increase of temperature but levelled off at temperatures ${\geq}527^{\circ}C$. The rate of devolatilization could be expressed by a shrinking particle model which was ruled by the reaction rate. The activation energy ranged from 13.1 to 18.5 kJ/g mol.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.191-196
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• 1997

The isothermal reduction on $Pt/MoO_3/SiO_2$ at $50^{\circ}C$ demonstrates that the rate of hydrogen spillover is increased as calciantion temperature increases. That is due to the overlayer formation over the surface of Pt crystallites, investigated by TEM and CO chemisorption. It is known that reaction mechanism of skeletal isomerization of 1-butene into iso-butene is composed of 2 step such as formation of carbonium ion and isomerization of methyl group. It is expected that the increase of i-butene yield after calcination at $250^{\circ}C$ is due to increased rate of hydrogen spillover coming from first, overlayer formation over Pt surface and second, chlorine lessoning from $PtCl_x$ precursor.