Titania-Silica Mixed Oxides

Dutoit, D.C.M.; Schneider, M.; Baiker, Alfons

doi:10.1006/jcat.1995.1118

Cited by 360 publications

(173 citation statements)

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“…The absorption bands at 3430 and 1630 cm −1 or so, as observed in all spectra, are attributed to the stretching mode of hydroxyl. 20,21 The absorption peak of the carbonyl group at about 1690 cm −1 in EDTA shifts to 1630 cm −1 in the spectrum of the CS-EDTA nanoparticles and the core/shelltype Ag/CS nanoparticles, as the carboxyls in EDTA molecules are ionized and overlapped with bending vibration of hydroxyl. 22 At the same time, the amino band (at 1540 cm −1 ) in the spectrum of pure chitosan disappears in the CS-EDTA nanoparticles and the core/shell-type Ag/CS nanoparticles, suggesting that the amino groups are in their protonated state whose absorption peak (around 1620 cm ).…”

Section: Resultsmentioning

confidence: 99%

Preparation and Characterization of Core/Shell-type Ag/Chitosan Nanoparticles with Antibacterial Activity

Yue¹,

Wang²,

Kang³

et al. 2011

Bulletin of the Korean Chemical Society

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Making use of chitosan (CS) and ethylenediaminetetraacetic acid (EDTA) as a reaction system, CS-EDTA nanoparticles were synthesized through a facile counterion complex coacervation method. Ag + could enter porous CS nanoparticles synthesized with this method, allowing Ag nanoparticles within chitosan nanoparticles were synthesized by reducing silver nitrate with chitosan. Because of the noncovalent interaction between CS and EDTA, the EDTA could be easily removed via dialysis against water, and pure core/shell-type Ag/CS nanoparticles could be obtained. The nanoparticles showed higher antibacterial activity toward E. coli than the active precursor Ag nanoparticles and CS.

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Section: Resultsmentioning

confidence: 99%

Preparation and Characterization of Core/Shell-type Ag/Chitosan Nanoparticles with Antibacterial Activity

Yue¹,

Wang²,

Kang³

et al. 2011

Bulletin of the Korean Chemical Society

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“…It is observed that there was not obvious FT-IR difference for Ag/AgBr/SFN before and after photocatalytic reaction, which indicates that the magnetic photocatalyst was stable enough to some extent. The characteristic absorption bands at around 800 and 1100 cm À1 are attributed to the symmetric vibration and asymmetric stretching vibration of Si-O-Si, respectively (Dutoit et al, 1995). On the one hand, it reveals the existence of SiO 2 on the catalyst surface, though SiO 2 is generally regarded as an interlayer between Ag/ AgBr and magnetic core.…”

Section: Xrd Uv-vis Drs and Ft-ir Measurementmentioning

confidence: 99%

Degradation of Acid Orange 7 using magnetic AgBr under visible light: The roles of oxidizing species

et al. 2009

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a b s t r a c tAgBr was creatively immobilized on a magnetic substrate (SiO 2 -coated Fe 3 O 4 nanoparticle, SFN) to achieve magnetic separation after visible light-driven photocatalytic oxidation (PCO). The resulted Ag/ AgBr/SFN was characterized by TEM, vibrating sample magnetometer and other techniques. It is found that the average diameter of the Ag/AgBr/SFN particle is less than 20 nm. The typical superparamagnetic behavior of Ag/AgBr/SFN implies that the catalyst can be magnetically separated. The physicochemical features of the used Ag/AgBr/SFN after visible light irradiation were not dramatically changed by X-ray diffraction, UV-Vis diffuse reflectance spectra and Fourier transform-infrared analysis. SiO 2 interlayer was proven to slightly increase the degradation efficiency for an azo dye Acid Orange 7. UV-Vis spectra and HPLC analysis indicated that the dye was oxidized and decomposed. The photoactivity of Ag/AgBr/ SFN was partly maintained after successive PCO under visible light. In order to evaluate the roles of e À -h + pairs and reactive oxygen species, the quenching effect was examined by employing Ag/AgBr/ SFN and commercial TiO 2 (P-25) under visible light (k > 400 nm) and UV-A irradiation, respectively. Active h + and the resulting Å OH played the major roles for degradation. The effect of active h + and Å OH were proven to be highly dependent on the concentration of photocatalysts. The effect of Å OH was more obvious for P-25, while that of active h + was more predominant for Ag/AgBr/SFN.

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“…4 was seen in 3Al:1Si aerogels formulated with added Ti using the T25 Boehmite precursor, but not in the corresponding P2 formulations. This band is present in the T25 aerogels regardless of the pH of the initial T25 suspension, and might be influenced by the larger d spacing 5 of the T25 crystallites compared to P2, as determined by x-ray diffraction, or to lower associated free -OH in the T25 preparations.…”

Section: Ftir Characterizationmentioning

confidence: 86%

Tailoring of Boehmite-Derived Aluminosilicate Aerogel Structure and Properties: Influence of Ti Addition

et al. 2011

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Aluminosilicate aerogels offer potential for extremely low thermal conductivities at temperatures greater than 900˚C, beyond where silica aerogels reach their upper temperature limits. Aerogels have been synthesized at various Al:Si ratios, including mullite compositions, using Boehmite (AlOOH) as the Al source, and tetraethoxy orthosilicate as the Si precursor. The Boehmite-derived aerogels are found to form by a self-assembly process of AlOOH crystallites, with Si-O groups on the surface of an alumina skeleton. Morphology, surface area and pore size varies with the crystallite size of the starting Boehmite powder, as well as with synthesis parameters.Ternary systems, including Al-Si-Ti aerogels incorporating a soluble Ti precursor, are possible with careful control of pH. The addition of Ti influences sol viscosity, gelation time pore structure and pore size distribution, as well as phase formation on heat treatment.

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Titania-Silica Mixed Oxides

Cited by 360 publications

References 0 publications

Preparation and Characterization of Core/Shell-type Ag/Chitosan Nanoparticles with Antibacterial Activity

Preparation and Characterization of Core/Shell-type Ag/Chitosan Nanoparticles with Antibacterial Activity

Degradation of Acid Orange 7 using magnetic AgBr under visible light: The roles of oxidizing species

Tailoring of Boehmite-Derived Aluminosilicate Aerogel Structure and Properties: Influence of Ti Addition

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