• 산업기술연구
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• 제23권A호
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• pp.199-206
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• 2003

The charcoal-encapsulated methyl silica microcapsules were prepared by a O/W microemulsion sol-gel method, and the adsorption properties on aquatic humic acid were investigated. The capsules prepared were spherical, $100{\sim}1000{\mu}m$ in size. The size distribution was controllable by adjusting the size of charcoal powder, charcoal/methyl silica ratio, and agitating speed in O/W sol-gel process. Adsorption efficiency of charcoal for aquatic humic acid was decreased after encapsulation by methyl silica shell. The decreased adsorption efficiency can be dependent on the decrease of the BET surface area and pore volume after encapsulation. Diffusion properties of humic acid through the capsule shell also played an important role on adsorption efficiency. Therefore, the reasonable target pollutants for the capsules can be VOC or odor molecules which can overcome diffusion barrier through shell of capsules in air condition. Functionalization methods for the charcoal-encapsulated $CH_3(SiO)_n$ microcapsules by incorporation of $TiO_3$ as a phtocatalytic function and by incorporation of inorganic pigment as a color function were also investigated. $TiO_2$ coating properties were controllable by adjusting pH, temperature, and the concentration of $TiOSO_4$. In XRD measurement, the crystal form of the coated $TiO_2$ was anatase. For the colorization of the capsules, inorganic pigments were more efficient than organic dyes, and various color was introduced to the capsules using inorganic pigments.

• 한국응용과학기술학회지
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• 제22권3호
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• pp.281-288
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• 2005

The silica nanoparticles were used as support of catalyst, filling material, electronic assembler, thin film material, and sensor material. And, the titania nanoparticles were used as pigment, dielectric substance, sensor and photocatalyst. In this paper, the spherical composite particles of $TiO_2/SiO_2$with narrow size distribution and phase pure were synthesized by ultrasonic spray pyrolysis method from $TiOSO_4$ and colloidal silica solution. Using ultrasonic apparatus, this starting solution was vaporized to droplets, and these droplets were induced into tube furnace by carrier gas. The resulting composite powder was characterized by scanning electron microscopy, X-ray diffraction analysis, TG-DTA, in vitro sun protection factor(SPF) and BET surface area analysis.

• 공업화학
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• 제21권4호
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• pp.417-423
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• 2010

파라자일렌(p-xylene) 분리용 흡착제로서 효과적인 그래뉼 형태의 바인더리스 ZSM-5 성형체를 제조하는 방법을 검토하였다. $SiO_2/Al_2O_3$ = 50인 ZSM-5 결정분말에 무기 바인더인 colloidal silica sol 30 wt% 용액과 유기첨가물인 microcrystalline cellulose를 첨가하여 구형화한 후, 소성, 바인더리스 처리, ${NH_4}^+$ 이온교환, 활성화 등의 과정을 거쳐 충분한 강도(0.721 kgf) 및 높은 결정화도(94.6%)와 넓은 BET 비표면적($379.2m^2$/g)을 갖는 흡착제를 제조하였다. 제조된 성형체의 흡착특성을 평가하기 위해 자일렌 3가지 이성질체를 1 : 1 : 1의 무게비로 혼합하여 $100^{\circ}C$에서 회분식 흡착실험을 수행한 결과 제조된 바인더리스 ZSM-5 성형체는 상용흡착제보다 파라자일렌에 대해 높은 선택적 흡착성능을 나타냈다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.610-615
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• 2001

Over 800 thousand tons per year (TPY) agricultural biowastes, such as sugar cane bagasse, sugarcane leaf, rice straw, rice husk and corn leaf, are produced in Taiwan. These biomasses are the major types of agricultural wastes and are abundantly available. However, these biowastes cause disposal and landfill problems. Ossification ashes of the agricultural biowastes containing 70-95 % amorphous silica would make the utilization system of agricultural biowaste ashes become highly economically and environmentally attractive. Experimentally, high crystallinity (99%$^{+}$) zeolites ZSM-5 and ZSM-48 synthesized from the reaction mixtures containing a silica source from ashes of these biowastes gasification were investigated. Tetrapropylammonium bromide (TPABr) and 1,6-diamino-hexane (C$_{6}$ DN) were used as structure-directing agents in syntheses of ZSM-5 and ZSM-48, respectively. X-ray powder diffraction (XRD) and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDX) data indicated that ZSM-5 or ZSM-48 with a high crystallinity can be obtained within 48 hours of crystallization in the high pressure (15-20 atm) autoclave at 393-473 K. The Si/Al ratios of synthetic zeolite products were determined by X-ray fluorescence (XRF) and induced couple plasma/mass spectroscopy (ICP/MS). It was observed that the ZSM-5 crystals a.e composed of hexagonal rod-shaped crystals with typically 8-13 пm in size by SEM. In addition, ZSM-48 crystalline materials are composed of spherical aggregates of needle-shaped or rod-like crystals with typically 2-3 пm in diameter and 6-8 пm in length.h.

• 한국세라믹학회지
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• 제42권8호
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• pp.554-560
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• 2005

The engineering ceramic needs the properties of high strength, hardness, corrosion-resistance and heat-resistance in order to withstand thermal shock or applied nonuniform stresses without failure. The densely coated porous ceramics can be used for machine component, electromagnetic component, bio-system component and energy-system component by their high-performances from superior coating properties and light-weight characteristics due to the structure including pore by itself. In this study we controlled the porosity of silica and alumina, $8.2\~25.4\%$ and $23.4\~36.0\%$, respectively, by the control of sintering temperature and starting powder size. We made bilayer structures, consisting of a transparent glass coating layer bonded to a thick substrate of different porous ceramics by a thin layer of epoxy adhesive, facilitated observations of crack initiation and propagation. The elastic modulus mismatch could be controlled using different porous ceramics as the substrate layer. Then we applied 150 N force using WC sphere with a radius of 3.18 mm by Hertzian indentation. As a result, the crack initiation in the coating layer was delayed at lower porosity in the substrate layer, and the damage in the coating layer was relatively smaller at the bilayer structure coated on higher elastic substrate.

• 한국광물학회지
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• 제20권3호
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• pp.181-191
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• 2007

천연유리로 만든 보석들의 보석학적 특징을 알아보기 위하여 중국 광동성 마오밍산 텍타이트와 백두산에서 채취한 흑요석을 대상으로 편광 및 반사현미경, 주사전자현미경, 비중 및 굴절율 측정, X-선형광분석, ICP-MS분석, X-선회절분석, 전자현미분석 등을 실시하였다. 중국산 텍타이트와 북한산 흑요석은 모두 검고, 패각상 단구를 나타내며, 수 mm 두께로 연마하였을 경우에는 모두 짙은 갈색의 반투명한 특징을 나타낸다. 텍타이트는 $4{\sim}10 cm$ 크기의 길쭉한 원통형 모양으로, 또는 직경이 $3{\sim}5 cm$인 구형으로 산출된다. 텍타이트의 표면에는 직경이 최대 3 mm인 함몰구조가 있는 것이 특징이다. 텍타이트의 모스경도는 $5{\sim}5.5$, 비중은 2.66이며, 단굴절을 일으키며, 굴절율은 1.51이다. 텍타이트 속에는 다수의 구형 기포가 분산되어 있으며, 규질성분이 높은 유리질물질이 존재한다. X-선회절 분석결과 비정질상태임이 확인되었다. 백두산 흑요석은 두 가지 형태로 나타난다. 즉, 균질한 검은색의 흑요석과 백색 결정을 함유하고 있는 것 등이다. 주된 차이점인 굴절율은 $1.49{\sim}1.50$으로서 텍타이트보다는 작으며, 비중은 텍타이트보다 다소 큰 $2.67{\sim}2.68$을 나타낸다. 또한 구형 기포 내포물이 없는 대신 새니딘과 자철석 침상결정을 함유하고 있다.