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Effect of doped SiO2 and calcinations temperature on phase transformation of TiO2 photocatalyst prepared by sol-gel method
Lek Sikong,Jiraporn Damchan,Kalayanee Kooptarnond,Sutham Niyomwas
Songklanakarin Journal of Science and Technology , 2008,
Abstract: The purpose of this research was to study the effect of calcinations temperature and SiO2 addition on phase transformation,crystallite size, and photocatalytic activity of SiO2/TiO2 thin films by using indigo carmine as an indicator. Thecomposite particles were prepared by sol-gel method via calcinations at a temperature range of 300-700oC for 2 h, and thecomposite thin films were prepared by means of spin coating. The microstructure and crystallite size of pure TiO2 and SiO2/TiO2 composite powders were characterized by using XRD, SEM and DTA. It was found that anatase structures wereformed at a calcinations temperature range of 300-600oC and mixed phases of anatase and rutile were observed at a temperatureof 700oC. Crystallite size of pure TiO2 tends to increase with an increase in calcinations temperature. Doped SiO2in the TiO2 has an effect on crystal phases and crystallite size of the composite powders and thin films, resulting in thechange of the photocatalytic activity of TiO2.
Ru/SiO2 AND CuRu/SiO2 PREPARED BY SOL-GEL: EFFECT OF pH AND WATER AMOUNT
Orellana,Fresia; Plaza De Los Reyes,Jorge; Urizar,Silvio;
Journal of the Chilean Chemical Society , 2003, DOI: 10.4067/S0717-97072003000200006
Abstract: ru(1%)/sio2 and cu(1%)ru(1%)/sio2 catalysts were prepared by cogelation. the effect of ph and the amount of water on the physical-chemical properties and the catalytic properties of them were analyzed. the acid medium increased the formation of microporosity and the formation of small size of metallic ruthenium particle. the variation of the water quantity used in the gelation not modify considerably the texture neither the dispersion of the noble metal. the reduction level of all prepared catalyst was similar, showing displacement in some of reduction peaks. the toluene hydrogenation indicated that the conversion and the quantity of hydrogenate product varied with the ph and the quantity of water used in the gelation. the addition of copper to ru/sio2 catalysts diminished the reactive conversion and their hydrogenant activity
Ru/SiO2 AND CuRu/SiO2 PREPARED BY SOL-GEL: EFFECT OF pH AND WATER AMOUNT  [cached]
Fresia Orellana,Jorge Plaza De Los Reyes,Silvio Urizar
Journal of the Chilean Chemical Society , 2003,
Abstract: Ru(1%)/SiO2 and Cu(1%)Ru(1%)/SiO2 catalysts were prepared by cogelation. The effect of pH and the amount of water on the physical-chemical properties and the catalytic properties of them were analyzed. The acid medium increased the formation of microporosity and the formation of small size of metallic ruthenium particle. The variation of the water quantity used in the gelation not modify considerably the texture neither the dispersion of the noble metal. The reduction level of all prepared catalyst was similar, showing displacement in some of reduction peaks. The toluene hydrogenation indicated that the conversion and the quantity of hydrogenate product varied with the pH and the quantity of water used in the gelation. The addition of copper to Ru/SiO2 catalysts diminished the reactive conversion and their hydrogenant activity
Optimization of preparation conditions of ZnO–SiO2 xerogel by sol–gel technique for photodegradation of methylene blue dye
R. M. Mohamed,E. S. Baeissa,I. A. Mkhalid,M. A. Al-Rayyani
Applied Nanoscience , 2013, DOI: 10.1007/s13204-012-0074-z
Abstract: The ZnO–SiO2 xerogel photocatalyst was prepared via the sol–gel technique and applied for photodegradation of methylene blue (MB) dye. The optimum conditions for preparation of ZnO–SiO2 gel is 30:70 ZnO:SiO2 molar ratio and TEOS:C2H5OH:H2O:HNO3 is 1:16:12:0.04 molar ratios at 30°C for 30 min, at these conditions the photoactivity of ZnO–SiO2 xerogel was 99% at a surface area of 500 m2/g after 60 min. The optimum loading of ZnO–SiO2 photocatalyst was 0.050 wt% that gives 99% MB dye removal efficiency after 40 min. The overall kinetics of photodegradation of MB dye using ZnO–SiO2 photocatalyst was found to be of the first order.
Preparation of SiO2 Microspheres by Two―step Catalytic Sol―Gel Method
ZHAO Bei-Bei, XU Chan-Chan, TANG Tao, LI Tong, ZHANG Wei-Bing, WANG Feng-Yun
无机材料学报 , 2011, DOI: 10.3724/sp.j.1077.2011.01090
Abstract: Micrometer SiO2 microspheres were prepared by two―step catalytic Sol―Gel method with tetraethoxysilane (TEOS) as starting material and N,N―Dimethylformamide (DMF) as template. The effects of some factors on the diameter and particle size distribution of the SiO2 microspheres were discussed, such as H2O quantity and ethanol quantity during the first catalytic process, the electrolyte concentration and stirring speed during the secondary catalytic process. SiO2 microspheres were characterized by SEM, Zetasizer, BET measurements and microscope―particle image analysis system. Results show that SiO2 microspheres are mostly regular―ball with no particle agglomeration. The mean particle size (D50) is 8.9μm, and the particle size distribution follows typical Gaussian distribution. The specific surface area is 546.67m2/g, and pore volume is 0.7142m3/g, with a narrow pore size varied from 2nm to 8nm. Also the particle size increases with water quantity, ethanol quantity and NaCl concentration increaing, but decreases with stirring speed acceleration.
Scanning electron microscopy study of protein immobilized on SIO2 Sol-gel surfaces
Assis, O.B.G.;
Brazilian Journal of Chemical Engineering , 2003, DOI: 10.1590/S0104-66322003000300014
Abstract: uniform attachment of enzymes to solid surfaces is essential in the development of bio and optical sensor devices. immobilization by adsorption according to hydrophilic or hydrophobic nature is dependent on the charges and defects of the support surfaces. sol-gel sio2 densified glass surfaces, frequently used as supports for protein immobilization, are evaluated via scanning electron microscopy. the model protein is globular enzyme lysozyme, deposited by adsorption on functionalized surfaces. formation of a protein layer is confirmed by ftir spectroscopy, and the sem images suggest discontinuous adsorption in areas where cracks predominate on the glass surface.
Scanning electron microscopy study of protein immobilized on SIO2 Sol-gel surfaces  [cached]
Assis O.B.G.
Brazilian Journal of Chemical Engineering , 2003,
Abstract: Uniform attachment of enzymes to solid surfaces is essential in the development of bio and optical sensor devices. Immobilization by adsorption according to hydrophilic or hydrophobic nature is dependent on the charges and defects of the support surfaces. Sol-gel SiO2 densified glass surfaces, frequently used as supports for protein immobilization, are evaluated via scanning electron microscopy. The model protein is globular enzyme lysozyme, deposited by adsorption on functionalized surfaces. Formation of a protein layer is confirmed by FTIR spectroscopy, and the SEM images suggest discontinuous adsorption in areas where cracks predominate on the glass surface.
STRUCTURE AND BIREFRINGENCE PROPERTIES OF SiO2-TIOPHENES XEROGELS SYNTHESIZED BY SOL-GEL-TEMPLATE  [PDF]
H. B SENIN,,KANCONO
Journal of Sustainability Science and Management , 2007,
Abstract: The ceramic tubular substrates of SiO2-thiophenes as a ceramic membrane were prepared successfully by the combining method of sol-gel-template process. The organic precursor of 2,5-bis(trimethoxsilyl) terthiophene was used as a template agent and tetraethoxysilane (TEOS) was used as organic or ingorganic silicon source. The gel formations of alkoxides are taken by condensation and polymerizations of TEOs with the catalyst ammonium fluoride, after mixing with the precursor. Characterizations were taken by NMR solid, SEM and XR-powder diffraction. The results showed that surface morphologies of its membranes are defect-free, and the bond-linking structure has been formed between silicate and template agent. The (SiO2) membrane prepared from TEOS has amorphous phase. The studies reveal that the silicone is mainly in tetrahedral coordination and combining with terthiophene units as a nanostructure to form lamellar structure. The optical birefringence properties of SiO2-thiophenes hybrid aerogels in the visible range strongly depend on amount of organic unit’s modifier. The higher transparency is observed for aerogels having higher content of alkoxysilane (TEOS), and than for the higher birefringence, normally observed for aerogels containing higher quantity of thiophenes units.
Design and Preparation of SiO2/TiO2/SiO2-TiO2 Antireflective Coatings with Excellent Abrasion-resistance and Transmittance via Sol-Gel Process
YE Long-Qiang, ZHANG Qing-Hua, ZHANG Yu-Lu, ZHANG Xin-Xiang, JIANG Bo
无机材料学报 , 2012, DOI: 10.3724/sp.j.1077.2012.11607
Abstract: Triple-layer broadband antireflective (AR) coatings with excellent abrasion-resistance and transmittance were designed using the theory of optical coating design. And the designed coatings were prepared on K9 glass via Sol-Gel process in this work. SiO2 and TiO2 sols were prepared using tetraethylorthosilicate (TEOS) and titanium tetraisopropoxide (TTIP) as precursors, respectively, and hydrochloric acid as catalyst. It is found that the average transmittance of the AR coatings over the entire visible region can reach 98.7%, which is 7.1% higher than that at the blank K9 glass. Moreover the transmittance of the AR coating does not obviously decrease after abrasion test, showing the excellent abrasion-resistance of the AR coatings. Hexamethyldisiloxane (HMDS) is further used to modify the surface of the AR coatings, which greatly improves the hydrophobicity of the coatings, and thus gives the AR coatings excellent environmental resistance.
Sb doping effects and oxygen adsorption in SnO2 thin films deposited via sol-gel
Geraldo, Viviany;Scalvi, Luis Vicente de Andrade;Morais, Evandro Augusto de;Santilli, Celso Valentim;Pulcinelli, Sandra Helena;
Materials Research , 2003, DOI: 10.1590/S1516-14392003000400004
Abstract: transparent electrically conducting antimony-doped sno2 thin films have been prepared by sol-gel dip-coating process from colloidal aqueous suspension. the effect of doping content on the structural, optical and electrical properties is analyzed. results from infrared optical transmission and reflection have shown that the higher the sb concentration the lower the transmission intensity and the higher the reflection signal. absorption intensity increases as well. results of x-ray reflectometry and electron microscopy have shown that the density of films fired at 400 °c after each dip is higher than that of multi-dipped films prepared with a single annealing. both the electrical characteristics in the dark and the increase in conductivity as function of illumination through different filters, at 190 k, evidence that the transport properties of these films are dominated by the presence of defects, including the trapping at grain boundary due to excess of oxygen.
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