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1.
Nanoparticles of SiO2 or TiO2 have been added in the preparation of heat-resisting concretes of two types. The major technical and chemical characteristics
have been determined. Features have been found in some of the technological operations in making the concretes of both types,
and also aspects of the physicomechanical properties. Higher chemical stability has been found for heat-resisting concrete
containing TiO2 nanoparticles in an NaOH solution. 相似文献
2.
Philomena Schlexer Hsin-Yi Tiffany Chen Gianfranco Pacchioni 《Catalysis Letters》2017,147(8):1871-1881
3.
Adsorption of thallium cations on RuO<Subscript>2</Subscript>–TiO<Subscript>2</Subscript> electrodes
S. Ferro M. Donatoni A. De Battisti V. N. Andreev 《Journal of Applied Electrochemistry》2007,37(11):1389-1394
The electrochemical ion-exchange properties of RuO2–TiO2 film electrodes with different composition have been studied in acidic and alkaline media. Thallium-cation uptake has been
observed only from the latter and its extent was found to be a function of electrode potential and composition. At potentials
near 0.0 V (RHE), the amount of adsorbed Tl+ exhibited a maximum, and decreased with increasing potential, reaching a broad minimum in the range 0.4–0.8 V. A further
increase in the electrode potential, above about 1.0 V, led to an increase of adsorbed thallium species, essentially due to
deposition of a few layers of Tl(III) hydroxide. In fact, the release of the latter species was found to be much slower than
that of thallium ions adsorbed at 0.0 V. For the latter, in turn, the double injection/ejection mechanism, currently accepted
to explain the charge-storage in oxide electrodes, seems to be confirmed. The high Γ values attained at 0.0 V indicate that
the large ionic radius of Tl+ does not prevent its diffusion through the thinner pore texture of the oxide coatings, possibly because of its poor hydration,
related with lower charge density at the ion surfaces. 相似文献
4.
In this study, degradation aspects and kinetics of organics in a decontamination process were considered in the degradation
experiments of advanced oxidation processes (AOP),i.e., UV, UV/H2O, and UV/H2O,/TiO2 systems. In the oxalic acid degradation with different H2O2 concentrations, it was found that oxalic acid was degraded with the first order reaction and the highest degradation rate
was observed at 0.1 M of hydrogen peroxide. Degradation rate of oxalic acid was much higher than that of citric acid, irrespective
of degradation methods, assuming that degradation aspects are related to chemical structures. Of methods, the TiO2 mediated photocatalysis showed the highest rate constant for oxalic acid and citric acid degradation. It was clearly showed
that advanced oxidation processes were effective means to degrade recalcitrant organic compounds existing in a decontamination
process. 相似文献
5.
N. V. Lebukhova V. S. Rudnev P. G. Chigrin K. S. Makarevich I. B. Lukiyanchuk N. F. Karpovich 《Catalysis in Industry》2011,3(3):294-300
Two methods were used to obtain a catalytically active oxide coating on the surface of titanium for the catalytic afterburning
of diesel soot: plasma electrochemical formation of an oxide film on the surface of titanium and extraction pyrolytic deposition
of the Li2Cu2(MoO4)3 compound. The Li2Cu2(MoO4)3/TiO2 + SiO2/Ti compositions synthesized by the single-step extraction pyrolytic treatment of the oxidized surface of titanium ensured
a high burning rate of soot of ∼300°C. The subsequent deposition of Li2Cu2(MoO4)3 lowers the activity of the catalyst, due probably to the growth of molybdate phase crystallites and the filling of open oxide
film pores. Double lithium-copper molybdate is able to reduce appreciably the concentration of CO in the oxidation products
of soot. The advantages of these methods are the possibility of forming high-cohesion durable coatings on surfaces of any
complexity, the simplicity of their implementation, and high productivity and low cost. The obtained results can be recommended
for use in developing methods for creating composite coatings on catalytic soot filters. 相似文献
6.
For high solar conversion efficiency of dye-sensitized solar cells [DSSCs], TiO2 nanofiber [TN] and Ag-doped TiO2 nanofiber [ATN] have been extended to be included in TiO2 films to increase the amount of dye loading for a higher short-circuit current. The ATN was used on affected DSSCs to increase
the open circuit voltage. This process had enhanced the exit in dye molecules which were rapidly split into electrons, and
the DSSCs with ATN stop the recombination of the electronic process. The conversion efficiency of TiO2 photoelectrode-based DSSCs was 4.74%; it was increased to 6.13% after adding 5 wt.% ATN into TiO2 films. The electron lifetime of DSSCs with ATN increased from 0.29 to 0.34 s and that electron recombination was reduced. 相似文献
7.
V. P. Kobyakov I. V. Novikov M. A. Sichinava 《International Journal of Self-Propagating High-Temperature Synthesis》2011,20(3):172-175
Explored was the combustion of Fe2O3/TiO2/Al thermit mixtures in steel tubes upon variation in green composition and with special emphasis on the dependence of combustion temperature T c and burning velocity U on reaction heat Q. Special attention was given to incompleteness of combustion for compositions with low Q. 相似文献
8.
TiO2-Al2O3 mixed oxides with different compositions ranging from 40wt-% to 95wt-% of TiO2 were prepared by sol-gel method and impregnated with different amounts of VO x . Supports and catalysts were characterized by X-ray diffraction (XRD), physisorption, temperature preprogrammed reduction (H2-TPR), and ammonia temperature programmed desorption (NH3-TPD). TiO2 content in the support had obvious effect on the crystal structure, texture characteristic, acid property, and catalytic activity in dehydrogenation of ethylbenzene (EB) with carbon dioxide. The highest catalytic activity was acquired when the TiO2 content was 50 wt-%. 相似文献
9.
Woo-Hee Kim Hyungjun Kim Han-Bo-Ram Lee 《Journal of Coatings Technology and Research》2017,14(1):177-183
Thin film optics, based on light interference characteristics, are attracting increasing interest because of their ability to enable a functional color coating for various applications in optical, electronic, and solar industries. Here, we report on the dependence of coloring characteristics on single-layer TiO2 thicknesses and alternating TiO2/Al2O3 multilayer structures prepared by atomic layer deposition (ALD) at a low growth temperature. The ALD TiO2 and Al2O3 thin films were studied at a low growth temperature of 80°C. Then, the coloring features in the single-layer TiO2 and alternating TiO2/Al2O3 multilayers using both the ALD processes were experimentally examined on a TiN/cut stainless steel sheet. The Essential Macleod software was used to estimate and compare the color coating results. The simulation results revealed that five different colors of the single TiO2 layers were shown experimentally, depending on the film thickness. For the purpose of highly uniform pink color coating, the film structures of TiO2/Al2O3 multilayers were designed in advance. It was experimentally demonstrated that the evaluated colors corresponded well with the simulated color spectrum results, exhibiting a uniform pink color with wide incident angles ranging from 0° to 75°. This article advances practical applications requiring highly uniform color coatings of surfaces in a variety of optical coating areas with complex topographical structures. 相似文献
10.
Wei Xie Xinyan Xiao Yichao Zhao Weiping Zhang 《Journal of Coatings Technology and Research》2017,14(5):1147-1158
TiO2/MoS2 composite was encapsulated by hydrophobic SiO2 nanoparticles using a sol–gel hydrothermal method with methyltriethoxysilane (MTES), titanium tetrachloride (TiCl4), and molybdenum disulfide (MoS2) as raw materials. Then, a novel dual functional composite film with hydrophobicity and photocatalytic activity was fabricated on a glass substrates via the combination of polydimethylsiloxane adhesives and hydrophobic SiO2@(TiO2/MoS2) composite particles. The influence of the mole ratios of MTES to TiO2/MoS2 (M:T) on the wettability and photocatalytic activity of the composite film was discussed. The surface morphology, chemical compositions, and hydrophobicity of the composite film on the glass substrate were investigated by scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and water contact angle (water CA) measurements. The results indicated that the composite film exhibited stable superhydrophobicity and excellent photocatalytic activity for degradation of methyl orange (MO) even after five continuous cycles of photocatalytic reaction when M/T was 7:1. The water CA and degradation efficiency for MO remained at 154° and 94%, respectively. Further, the composite film showed a good non-sticking characteristic with the water sliding angle (SA) at about 4°. The SiO2@(TiO2/MoS2) composite consisting of hydrophobic SiO2 nanoparticles and TiO2/MoS2 heterostructure could provide synergistic effects for maintaining long-term self-cleaning performance. 相似文献
11.
12.
Rasoul Khosravi Ahmad Zarei Mohsen Heidari Ali Ahmadfazeli Mehdi Vosughi Mehdi Fazlzadeh 《Korean Journal of Chemical Engineering》2018,35(4):1000-1008
This study considers the feasibility of uptake of cephalexin, an emerging contaminant, from aqueous solutions by using green local montmorillonite (GLM), montmorillonite coated with ZnO (ZnO/GLM) and montmorillonite coated with TiO2 (TiO2/GLM) in the presence of H2O2. Batch adsorption experiments were carried out as a function of pH, initial concentration of the cephalexin, adsorbent dosage, contact time, and temperature. Finally, the adsorbents were characterized by XRD, SEM and FTIR analyses. XRD patterns showed dramatic changes in the adsorbents after loading with the nanoparticles, confirming successful placing of the nanoparticles onto GLM. The GLM mineral surface after nanoparticle loading appears to be fully exposed and more porous with irregular shapes in particles diameters of 1-50 microns. FTIR analyses also confirmed dramatic changes in surface functional groups after modification with these nanoparticles. The results showed that the removal efficiency of cephalexin was better at lower pH values. Totally, the removal efficiency increased with increase in adsorbent dosage and contact time and decreased with concentration and temperature increase. The thermodynamics values of ΔG o and ΔH o revealed that the adsorption process was spontaneous and exothermic. In isotherm study, the maximum adsorption capacities (qm) were obtained to be 7.82, 17.09 and 49.26 mg/g for GLM, ZnO/GLM and TiO2/GLM, respectively. Temkin constant (B T ) showed that adsorption of cephalexin from solution was exothermic for all three adsorbents. 相似文献
13.
A. Mukherjee N. Krishnamurthy 《International Journal of Self-Propagating High-Temperature Synthesis》2010,19(4):237-243
The direct preparation of V-Ti solid solution alloy by coreduction of V2O5 and TiO2 with Al in an attritor mill was investigated. The reduction of V2O5 with Al is highly exothermic, whereas reduction of TiO2 with Al is not sufficiently exothermic for a self-sustaining reaction. A range of compositions of a mixture of V2O5 and TiO2 can be so chosen as to make the overall reduction of V2O5 and TiO2 with Al sufficiently exothermic for a self-sustaining reaction. Initial studies were done to identify the reaction products
obtained by reducing V2O5 with Al. The reaction yielded the intermetallic phase (Al3V), V, and Al2O3. SEM images indicated melting and solidification of the phases, leading to agglomeration. Further experiments involved mixing
appropriate amounts of TiO2 with V2O5 and reducing the mixture with Al. XRD data for products showed the presence of V, V5Al8, and Al2O3. X-Ray Florescence (XRF) analysis and energy dispersive analyzer (EDAX) of SEM sample images indicated the formation of V-Ti
solid solution. Microstructure of the milled charges taken out prior to reaction initiation indicated morphology change in
Al powder and agglomeration/segregation of reactants. As a result, the reaction of V2O5 with the excess Al at certain regions also promoted the formation of vanadium aluminide. 相似文献
14.
L. G. Gerasimova R. F. Okhrimenko M. V. Maslova 《Theoretical Foundations of Chemical Engineering》2007,41(5):620-622
The hydrolysis of titanium(IV) sulfate during boiling in the presence of silica gel particles is considered. The scenario of solid-phase formation involves the sedimentation of hydrated titanium(IV) onto reactive silica gel particles; and individual phases of silicon(IV) and titanium(IV) hydroxides are formed. The quantitative ratio between the phases of the hydrated composition dictates the properties of its thermolysis products. Composition-property diagrams are plotted to determine the optimum parameters at which the titanium silicate product has high pigment properties. 相似文献
15.
In this study, polymeric hindered amine light stabilizers (HALS)-functionalized silica coated rutile titanium dioxide (TiO2-SiO2) nanoparticles were prepared by encapsulating commercially available TiO2-SiO2 nanoparticles with methyl methacrylate (MMA) and 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (PMPM) copolymers via miniemulsion polymerization. The obtained functional (TiO2-SiO2/P(MMA-co-PMPM)) fillers have been added to polyurethane acrylate (PUA) oligomers to get UV-curable nanocomposite coatings. The functionalization of the TiO2-SiO2 nanoparticles with polymeric HALS has been confirmed by infrared spectra (IR), thermogravimetric (TG), and X-ray photoelectron spectroscopy (XPS) analyses. The scanning electron microscope (SEM) micrographs indicated that homogeneous dispersion of TiO2-SiO2/P(MMA-co-PMPM) composite nanoparticles resulted in improved transparency and mechanical properties of the UV-curable PUA coatings. Rhodamine B (Rh.B) photodegradation measurement confirmed the excellent UV-shielding performance of PUA nanocomposite coatings containing TiO2-SiO2/P(MMA-co-PMPM). The addition of TiO2-SiO2/P(MMA-co-PMPM) composite nanoparticles reduced the UV-curable PUA coatings degradation rate dramatically. The UV-aging resistance of PUA coatings was improved significantly. Over all, the combination of TiO2-SiO2 nanoparticles and polymeric HALS offers an attractive way to fabricate the multi-functional fillers, which can be used to improve the mechanical properties and UV-aging resistance of PUA coatings simultaneously. 相似文献
16.
Pharatree Jaita Anucha Watcharapasorn Sukanda Jiansirisomboon 《Nanoscale research letters》2012,7(1):24
Lead-free piezoelectric compositions of the (1-x)Bi0.5(Na0.40K0.10)TiO3-x(Ba0.7Sr0.3)TiO3 system (when x = 0, 0.05, 0.10, 0.15, and 0.20) were fabricated using a solid-state mixed oxide method and sintered between 1,050°C and
1,175°C for 2 h. The effect of (Ba0.7Sr0.3)TiO3 [BST] content on phase, microstructure, and electrical properties was investigated. The optimum sintering temperature was
1,125°C at which all compositions had densities of at least 98% of their theoretical values. X-ray diffraction patterns that
showed tetragonality were increased with the increasing BST. Scanning electron micrographs showed a slight reduction of grain
size when BST was added. The addition of BST was also found to improve the dielectric and piezoelectric properties of the
BNKT ceramic. A large room-temperature dielectric constant, ε
r
(1,609), and piezoelectric coefficient, d
33 (214 pC/N), were obtained at an optimal composition of x = 0.10. 相似文献
17.
Zhi-Yuan Yang Guang-Yu Shen Yun-Peng He Xiao-Xia Liu Shui-Jin Yang 《Journal of Porous Materials》2016,23(3):589-599
The composite semiconductor photocatalyst TiO2/SiO2 was prepared by template-hydrothermal method using carbon spheres as the template. The structural and optical properties of TiO2/SiO2 were characterized by XRD, SEM, BET, UV–Vis DRS, TG-DTA, PL techniques. The formation of hydroxyl radical on the surface of TiO2/SiO2 was studied with terephthalic acid as the probe molecule, combined with fluorescence technique. The results showed that the specific surface area of TiO2/SiO2 composite was 327.9 m2/g, and the specific surface area of TiO2/SiO2 was larger than that of pure TiO2. Photocatalytic degradation of rhodamine B showed that TiO2/SiO2 composite oxide under visible light illumination 40 min, the degradation rate was 98.6 % and the degradation rate of pure TiO2 was only 11.9 %. The apparent first-order rate constant of TiO2/SiO2 was 33 times that of pure TiO2 and more than 6 times that of P25 when the molar ratio of Ti to Si was 1:1 under visible light irradiation. Moreover, it’s also as much as 5 times that of pure TiO2 and is more than 1 times that of P25 under UV light irradiation 25 min. Based on the experimental results, ·O2 ? and h+ were suggested to be the major active species which was responsible for the degradation reaction. The increased photocatalytic activity of TiO2/SiO2 may be mainly attributed to effectively suppressing the recombination of hole/electron pairs. After the photocatalyst TiO2/SiO2 was reused 5 times, the degradation rate of rhodamine B could reach 89.2 % under visible light irradiation. Moreover, The composite semiconductor photocatalyst TiO2/SiO2 was selective towards the degradation of rhodamine B. 相似文献
18.
Inseok Jang Hui Jun Leong Seong-Geun Oh 《Korean Journal of Chemical Engineering》2016,33(5):1647-1652
Nanosized TiO2 particles were prepared through facile sol-gel reaction by using microwave-assisted method. To investigate the effects of surfactants on the formation of TiO2, various additives (PVP, Triton X-100 and P123) were employed. The diameter of synthesized titania spheres could be controlled from 105 to 380 nm. The TiO2 particles prepared with P123 triblock copolymer showed large surface area and high pore volume. It was attributed to the fact that the pore site, where the surfactant template initially existed, was generated upon calcination process. The characteristics of prepared TiO2 nanoparticles were analyzed by using FE-SEM, TEM, XRD, FT-IR and N2 adsorption-desorption. As an application of prepared composites for water treatment, their photocatalytic performances for the degradation of methylene blue dye were examined by using UV-vis spectrophotometer under room light irradiation. The prepared TiO2 particles with Triton X-100 and P123 exhibited higher performance for methylene blue photo-degradation than that of P25. It was attributed to the effects of large specific surface area and high porosity. 相似文献
19.
D. Zare-Hossein-abadi A. Ershad-Langroudi A. Rahimi S. Afsar 《Journal of Inorganic and Organometallic Polymers and Materials》2010,20(2):250-257
Transparent nanocrystalline TiO2 thin films with high photocatalytic activity and photo-induced wettability were successfully deposited on a glass slide.
Crystal phase transformations and particle size of TiO2 were investigated. Structural and morphological properties of the films were investigated. The photocatalytic activity of
the TiO2 films was evaluated. It is found that the photocatalytic activity of TiO2 thin films is significantly decreased by increasing the annealing temperature, which results in a decrease in BET surface
area and an increase in crystal size. In addition, increasing film thickness within a certain range significantly improves
the photocatalytic activity without causing crack formation of the TiO2 films. Photocatalytic oxidation and photo-induced wettability conversion on the films were investigated. It is found that
photo-induced hydrophilic conversion is observed even on the samples annealed at high temperature. The best photo-generated
activities are obtained by optimization of dip-coating cycles and annealing temperatures. 相似文献
20.
PSA [poly-(styrene-methyl acrylic acid)] latex particle has been taken into account as template material in SiO2 hollow spheres preparation. TiO2-doped SiO2 hollow spheres were obtained by using the appropriate amount of Ti(SO4)2 solution on SiO2 hollow spheres. The photodecomposition of the MB (methylene blue) was evaluated on these TiO2-doped SiO2 hollow spheres under UV light irradiation. The catalyst samples were characterized by XRD, UV-DRS, SEM and BET. A TiO2-doped SiO2 hollow sphere has shown higher surface area in comparison with pure TiO2 hollow spheres. The 40 wt% TiO2-doped SiO2 hollow sphere has been found as the most active catalyst compared with the others in the process of photodecomposition of
MB (methylene blue). The BET surface area of this sample was found to be 377.6 m2g−1. The photodegradation rate of MB using the TiO2-doped SiO2 catalyst was much higher than that of pure TiO2 hollow spheres. 相似文献