• Analytical Science and Technology
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• v.21 no.6
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• pp.553-561
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• 2008

$CNT/TiO_2$ composites were prepared by using multiwall carbon nanotubes (MWCNT) and various titanium alkoxide precursors. The composites were comprehensively characterized by scanning electron microscopy (SEM), field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and UV-vis absorption spectroscopy. The photoactivity of the prepared materials under UV irradiation, was tested using the conversion of MB from model aqueous solution. Finally, according to the results of methylene blue (MB) removal experiment, we could see that sample CTOS have better MB removal effect than samples CTIP and CTPP.

• Applied Chemistry for Engineering
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• v.4 no.3
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• pp.497-504
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• 1993

The effect of DCCA (Drying Control Chemical Additives) on the drying of gel was investigated in order to determine an optimum drying condition of mullite precursor through sol-gel process. Aluminium sec-butoxide was synthesized from aluminium foil and then mullite powders were synthesized from Tetra-ethyl-ortho-silicate (TEOS) and the aluminium sec-butoxide. N, N-dimethyl formamide (DMF), Glycerol, 1, 4-Dioxane, and Oxalic acid were used as DCCA. Mullite powders that were calcined at 200, 900, 1100, and $1250^{\circ}C$ for 2hr were analysed by XRD, TG-DTA, FT-IR, and SEM in order to investigate structural change and characteristics of calcined powders. The results of this work showed that the drying time of gel was reduced to about half in the presence of 0.1mol DMF compared with the absence of DCCA and also calcined powders were obtained without remarkable structural change despite of the addition of DCCA.

• Journal of the Korean Ceramic Society
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• v.35 no.9
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• pp.953-957
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• 1998

The effects of catalysts and reactive conditions on the synthesis of aluminum alkoxides are investigated. HgCl2 and I2 as catalysts are used in the synthesis reaction for comparing to no addtion. The absorption peak in IR spectra according to Al-O-L bond of aluminum isopropoxide and aluminum sec-butoxide appear at near 1030cm-1 and 1060cm-1 respectively regardless of kinds of catalysts. The synthesis yield of alu-minum-isopropoxide was 90% in case of no catalyst addition and increased to all of 95% by addition of HgCl2 and I2 The synthesis yield of aluminum sec-butoxide is increased to 95% by addition of I2 catalyst com-paring to no addition.

• Korean Journal of Materials Research
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• v.6 no.5
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• pp.449-456
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• 1996

BaO, SrCI2.6H2O 그리고 Ti(OPri)4를 출발 원료로 사용하여 균일한 BaxSr1-xTiO3(BST) 솔을 합성하였고, BST 박막을 회전 코팅 법으로 Si 및 Pt/Ti/SiO2/Si 기판위에 제조하였다. 적외선 및 NMR 스펙트럼 분석으로 킬레이션 조제로 사용한 acetylacetone(AcAc)이 엔올 형태로 Ti-알콕사이드와 결합하여 솔 안정화에 기여함을 확인하였다. Xedrogel에 대한 DT/TGA 및 적외선 스펙트럼 결과로부터 페로브스카이트 상생성이 $600^{\circ}C$ 이상에서 이루어짐을 관찰하였다. $700^{\circ}C$에서 열처리한 박마은 -300(10 KHz)의 상대유전율을 나타내었고, 결정립의 저항 및 입계의 병렬 RC 성분으로 등가회로를 구성할 수 있었다.

• Proceedings of the Membrane Society of Korea Conference
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• 1996.10a
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• pp.55-57
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• 1996

다공성 무기막은 높은투과도와 뛰어난 내열.내화학성, 그리고 경제성 때문에 기존의 PSA공정이나 증류와 같은 고에너지 분리공정을 대체하는 공정으로 각광을 받고 있다. 무기재료막의 제조하는 방법으로 주로 알콕사이드를 사용하는 솔-젤법(1)과 금속(2) 또는 기상반응(3)을 이용하는 화학증착법이 사용된다. 또한 고온에서 수소를 연속적으로 분리하여 화학평형에 기인한 한계를 극복하여 높은 수율을 얻고자하는 막반응기에 관한 연구가 활발히 진행되고 있다. 본 연구에서는 $\alpha$-알루미나 지지체의 미세한 다공성 구조 내부에서 TEOS(Tetraethylorthosilicate)와 산성의 알코올-물 혼합물을 확산시켜 실리카 솔을 생성시킴과 동시에 젤화시켜 기공의 크기를 감소시켜 막을 제조하였다. 이렇게 제조된 막은 높은 투과도와 낮은 수소선택도(selectivity=3-4)를 보였고, 두번째 단계로 silica sol을 제조하여 진공 하에서 dip-coating을 행하였다. 이렇게 2단계로 기공 구조를 개선시킨 실리카 막은 저압에서 상대적으로 높은 수소의 분리도(selectivity=5-7)를 보였으며 여전히 높은 투과도를 갖는다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.4
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• pp.332-342
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• 1995

The important factors of reaction conditions in sol-gel transition of silicon alkoxide solution have been reviewed and discussed on the basis of Raman study. Various factors such as type of catalyst, alkoxide, solvent, drying control chemical additive and water content affect the conversion mechanism in sol-gel process.

• Journal of the Korean Ceramic Society
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• v.28 no.2
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• pp.167-175
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• 1991

In synthesizing hydrated zirconia powder by hydrolysis of Zr-alkoxides using ethanol as mutual solvent, three experimental parameters, namely, concentration of alkoxides and hydrolysis water and addition rate of hydrolysis water were varied systematically. Spherical, monodispersed, nonagglomerated and submicrometer sized powders were prepared at 0.3 M of Zr(n-OPr)4 and 0.05M of Zr(n-OBu)4 with wide ranges of hydrolysis water conditions i.e. 0.5-2.0M concentration and 1-20ml/min addition rate. During the hydrolsis, careful attention have to be paid to maintain homogeneous reaction by controlling the agitation of the reactant and the addition of the hydrolysis water. For more improved condition of monodispersity it was found that the key point is to shorten the self-nucleation time within several seconds as rapid as possible. In both alkoxides system, with higher concentration of alkoxide and hydrolysis water and with slow addition rate of hydrolysis water, hydrated zirconia powders synthesized showed tendency to fall in worse powder conditions.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2004.05a
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• pp.98-102
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• 2004

반도체 산업용 실리콘 잉곳의 절단공정에서 발생하는 폐슬러지 중에는 고순도의 실리콘이 함유되어 있으며, 이 슬러지로부터 분리, 회수한 Si로부터 실리콘화합물 합성하였다. 고비점의 potasium alkoxide 촉매 존재하에서 금속 실리콘과 에탄을 혹은 메탄올과 같은 알코올과의 고액반응에 의해 알콕시 실란을 합성할 수가 있었다 알콕시 실란을 합성반응속도는 반응온도에 크게 의존하였고 최적반응 온도는 $180^{\circ}C{\sim}195^{\circ}C$ 정도이었다. 촉매 첨가량에 따라 알콕시 실란의 반응율이 달라졌으며, 알콕시 실란의 반응율은 최고 90%로 높은 값을 나타내었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.5
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• pp.493-497
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• 1999

$TiO_2$ Powders were prepared by sol-gel method to testify the characteristics as the photocatalysts. The relationship between processing conditions (R-value (molar ratio of water to alkoxide)), heat treatment temperature, microstructures (crystalline phases), and properties (surface area, particle size) was examined. The optimal conditionsto improve the activity of photocatalyst for photobleaching of dyes in aqueous solution, Were determined.

• Applied Chemistry for Engineering
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• v.7 no.6
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• pp.1192-1203
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• 1996

$Al_2O_3-TiO_2$ composite oxide adsorbents which could be applied in high-temperature water were prepared by hydrolysis of aluminum and titanium alkoxide. The prepared adsorbents were calcined at $600{\sim}1400^{\circ}C$ and in order to investigate the various properties - the transition of crystals, thermal properties, and specific surface area, X-ray diffractometry, thermal analysis, FT-IR, SEM and BET method were employed. And the $Co^{2+}$ adsorption characteristics of these adsorbents in high-temperature water were investigated by batch adsorption experiment in a stirred autoclave. Since the adsorption of $Co^{2+}$ on the $Al_2O_3-TiO_2$ adsorbents was irreversible endothermic in the temperature range of $150{\sim}250^{\circ}C$, the standard enthalpy changes of 26, 43, and 80 mol% of $TiO_2$ on $Al_2O_3$ were in the range of $16.5{\sim}26.0kJ{\cdot}mol^{-1}$. The adsorbent of 26 mol% of $TiO_2$ on $Al_2O_3$ which was calcined at $600^{\circ}C$ for 2 hours showed the adsorption amount of $0.1674meq{\cdot}g^{-1}$ in the high temperature water at $250^{\circ}C$.