- Photocatalytic characteristics of nanometer-sized titania powders fabricated by a homogeneous-precipitation process
-
The photocatalytic characteristics of nanometer-sized TiO2 powder prepared by a homogeneous-precipitation process (HPP) were compared with those of a commercial powder to determine which powder was better able to remove metal ions, such as lead and copper, from aqueous equimolarmetal-ethylenediaminetetraacetic acid (EDTA) solution. In aqueouslead-EDTA solution, the TiO2 powder fabricated by HPPhad 3.5 times higher initial adsorption of lead ion and a 1.5 times faster rate for the complete elimination of lead ions than did the commercial powder. In an aqueous copper-EDTA solution, the TiO2 powder fabricated by HPP also showed higherinitial adsorption and a faster elimination rate for copper ions than did the commercial powder. Similarly, the photocatalyticproperties were enhanced as the specific surface area increased, and the TiO2 powder fabricated by HPP, which consisted of coagulated primary particles 20 nm in size, with chestnut-burr shapes, had a larger specific surface area (~180 m2/g) than that of the commercial powder (~55 m2/g).
- Lee, Kang Ryeol,Kim, Sun Jae,Song, Jae Sung,Lee, Ju Hyeon,Chung, Yun Joong,Park, Sung
-
-
Read Online
- Characterization of supported TiO2-based catalysts green-prepared and employed for photodegradation of malodorous DMDS
-
Titanium dioxide (TiO2)-based catalysts coated onto two supporting materials (Pyrex glass beads and porous polypropylene fibers) in laboratory have been prepared and characterized. A modified preparation process at low temperature involving the addition of distilled water, aqueous ammonia, and ferrous sulfate, respectively, was used to enhance the spontaneous precipitation of three TiO2-based catalysts. The Brunauer-Emmett- Teller surface area of three catalysts was ranged from 160.1 to 202.7 m 2/g. The surface morphology of three catalysts was identified by a scanning electron microscopy equipped with an X-ray energy dispersive spectrometer. The photocatalytic degradation of dimethyldisulfide was investigated using the supported TiO2-based catalysts. The original dimethyldisulfide almost was degraded within 2 h. A similar photocatalytic activity on degrading dimethyldisulfide was demonstrated in comparison with commercial catalysts. Simplicity, low cost, low energy consumption, and solvent-free are the advantages of this proposed method which can be used to photodecompose environmental organic pollutants effectively without heat treatment.
- Chuang, Li-Chin,Luo, Chin-Hsiang
-
-
Read Online
- Phase formation, crystal structure, and electrical conductivity of triple phosphates of alkali metals and titanium
-
For triple phosphates of composition A0.5A'0.5 Ti2(PO4)3 (A-A'=Li-Na, Na-K, K-Rb), phase formation is studied, the crystal structure is refined, and the electrical conductivity is measured. The compounds are classified with the NaZr 2(PO4)3 structure type (NZP, space group R 3? c). The phosphate frameworks are built of TiO6 octahedra and PO4 tetrahedra. Extraframework positions M1 are fully occupied by randomly distributed alkali cations. Positions M2 are vacant. Correlations are found between the structural distortion and electrical conductivity of the phosphates, on one hand, and the alkali cation size, on the other. Pleiades Publishing, Inc. 2006.
- Asabina,Pet'Kov,Boguslavskii,Malakho,Lazoryak
-
-
Read Online
- α-Diimine synthesis via titanium-mediated multicomponent diimination of alkynes with C-nitrosos
-
α-Diimines are commonly used as supporting ligands for a variety of transition metal-catalyzed processes, most notably in α-olefin polymerization. They are also precursors to valuable synthetic targets, such as chiral 1,2-diamines. Their synthesis is usually performed through acid-catalyzed condensation of amines with α-diketones. Despite the simplicity of this approach, accessing unsymmetrical α-diimines is challenging. Herein, we report the Ti-mediated intermolecular diimination of alkynes to afford a variety of symmetrical and unsymmetrical α-diimines through the reaction of diazatitanacyclohexadiene intermediates with C-nitrosos. These diazatitanacycles can be readily accessed in situ via the multicomponent coupling of TiNR imidos with alkynes and nitriles. The formation of α-diimines is achieved through formal [4 + 2]-cycloaddition of the C-nitroso to the Ti and γ-carbon of the diazatitanacyclohexadiene followed by two subsequent cycloreversion steps to eliminate nitrile and afford the α-diimine and a Ti oxo.
- Cheng, Yukun,Egger, Dominic T.,Frye, Connor W.,Kounalis, Errikos,Pearce, Adam J.,Tonks, Ian A.
-
p. 1469 - 1477
(2022/02/11)
-
- Photocatalytic degradation of methylene blue under UV and visible light by brookite-rutile bi-crystalline phase of TiO2
-
The phase junction of TiO2 nanoparticles plays an essential role in improving photocatalytic activity. Mixed phase brookite-rutile TiO2 nanoparticles with different phase compositions were synthesized through a hydrolysis method using nitric acid of different concentrations. The bi-crystalline phase was characterized by X-ray diffraction (XRD), Raman spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and Brunauer-Emmett-Teller (BET), UV-vis diffuse reflectance spectroscopy (DRS) and Photoluminescence (PL) analysis. Photoelectrochemical properties were investigated by transient photocurrent density (TPR) and electrochemical impedance spectroscopy (EIS). XRD and Raman results revealed that the brookite content increased in the sample when increasing the HNO3 concentration. The prepared mixed-phase TiO2 nanoparticles have mesopores with large surface areas ranging from 48.81 to 89.95 m2 g-1. UV-vis spectra showed a redshift of absorption edge from 398 nm to 408 nm with increasing brookite content. The optical band gaps which were obtained from the UV-vis spectra were decreased with increasing brookite content. Photoluminescence results showed that the sample prepared with 5.0 M nitric acid (BCTi-4) showed the lowest emission due to the electron-hole recombination. Furthermore, BCTi-4 revealed the highest photocurrent density of 6 μA cm-2 and the smallest Rct values of 3.30 kΩ. The photocatalytic properties of prepared samples were evaluated by the degradation of methylene blue under UV and visible light irradiation. The BCTi-4 exhibited the highest degradation rate that completely degraded methylene blue after 3 hours of UV irradiation and 36 hours under visible light irradiation. This was attributed to the synergetic effect of phase junction of brookite and rutile, which reduces the recombination of photoexcited electron-hole pairs and the optimal ratio of brookite and rutile. This journal is
- Kim, Min Gu,Lee, Ji Eun,Kim, Kang Seok,Kang, Jeong Min,Lee, Jeong Hoon,Kim, Kwang Ho,Cho, Min,Lee, Seung Geol
-
p. 3485 - 3497
(2021/03/03)
-
- Revealing the Role of the Intermediates during the Synthesis of BaTi5O11
-
BaTi5O11 has been extensively studied because of their microwave dielectrics properties. Traditionally, it is difficult to achieve this material as single-phase. Here, we report an effective method to obtain BaTi5O11 powder with nanometer-scale crystals, by solid-state reaction at moderate temperatures and using as precursors nanostructured particles consisting of BaTiO3 and TiO2. The main advantage is the intimate contact between the BaTiO3 and TiO2 that ensure, when the solid-state reaction takes place, the formation of complex solid compounds from three or more constituents. The formation mechanism of BaTi5O11 has been studied as a function of both the thermal treatment and the time reaction. The reaction was monitored by Raman spectroscopy combined with Confocal microscopy, the aim of this characterization technique is to provide the description of the general strategy and design principles to obtain BaTi5O11 powder. Consequently, this work is a challenging task for the compositional and structural study of complex inorganic nanoparticles.
- álvarez-Docio, Carmen María,Reinosa, Julián Jiménez,Canu, Giovanna,Buscaglia, María Teresa,Buscaglia, Vincenzo,Fernández, José Francisco
-
supporting information
p. 8120 - 8129
(2019/06/17)
-
- Transesterification Catalyst and Method for Producing Biodiesel Fuel Using Transesterification Catalyst
-
[Problem] To provide a catalyst for production of a biodiesel fuel, which is capable of producing a biodiesel fuel with high selectivity, at a high yield, and at a low cost even in the presence of a water content and a free fatty acid, and a biodiesel fuel production method using the catalyst. [Solution] Use of a titanium-containing mesoporous silica containing Ti and Si as skeleton constituent elements and having a pore diameter of 5 nm or greater as a transesterification catalyst enables a biodiesel fuel to be produced with high selectivity at a high yield through transesterification between an oil and an alcohol.
- -
-
-
- Ceramic structures for controlled release of biologically active substances
-
The present invention provides compositions for controlled drug delivery, dosage forms, and processes for producing dosage forms. In a composition aspect of the present invention, a composition including a drug and a ceramic structure is provided. The ceramic structure has either a hollow portion wherein the drug is included in the hollow portion or is a collection of smaller particles bound together.
- -
-
Page/Page column 6
(2008/06/13)
-