Preparation of pure rutile and anatase TiO2 nanopowders using RF thermal plasma

Oh, Seung-Min; Ishigaki, Takamasa

doi:10.1016/j.tsf.2003.12.043

Cited by 96 publications

(54 citation statements)

References 21 publications

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“…The lower f A and lower photocatalysis characteristics are useful for application to skin care cream [10]. The f A in the synthesized nanopowder can be controlled by changing the O 2 concentration in nanopowder processing [13,26]. The most important feature to be emphasized in the obtained XRD spectra is that no Ti, Al or Al 2 O 3 peaks were detected in nanopowder for 80%SCL and 70%SCL.…”

Section: Chemical Composition Assessment Of Synthesized Al-doped Tio mentioning

confidence: 99%

“…Several studies have examined the synthesis of TiO 2 nanoparticles using a steady-state type of inductively coupled thermal plasma (ICTP). They have mainly investigated control of its particle size and phase constituent [13,14,18]. However, some issues persist: the difficulty in controlling the synthesized particle size, and also the lower production rate from the instability of ICTP sustainability during heavy-load feeding of feedstock.…”

Section: Introductionmentioning

confidence: 99%

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A method for large-scale synthesis of Al-doped TiO₂nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

Kodama¹,

Tanaka²,

Kita³

et al. 2014

J. Phys. D: Appl. Phys.

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Abstract.A unique large-scale synthesis method for Al-doped TiO 2 nanopowder was developed using 20-kW Ar-O 2 pulse-modulated induction thermal plasmas (PMITP) with time-controlled feedstock feeding (TCFF). This PMITP-TCFF method is characterized by intermittent feedstock powder feeding synchronized with modulated power of the PMITP. The method enables heavy-load feeding of raw material powder to the thermal plasmas for complete evaporation. Synthesized nanopowder was analyzed using different methods including FE-SEM, XRD, BF-TEM, TEM/EDX mapping, XPS, and spectrophotometry. Results showed that Al-doped TiO 2 nanopowder can be synthesized with mean diameters of 50-60 nm. The Al doping in TiO 2 was confirmed from the constituent structure in XRD spectra, the uniform presence of Al on the nanopowder in TEM/EDX mapping, the chemical shift in XPS spectra, and the absorption edge shift in the optical property. The production rate of Al-doped TiO 2 nanopowder was estimated as 400 g h −1 .

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Section: Chemical Composition Assessment Of Synthesized Al-doped Tio mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A method for large-scale synthesis of Al-doped TiO₂nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

Kodama¹,

Tanaka²,

Kita³

et al. 2014

J. Phys. D: Appl. Phys.

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“…Accordingly, the concentration of oxygen directly influences the formation of the crystalline phases. As shown in [15], a low concentration of oxygen obtained by controlling the oxygen flow in the high-frequency thermal plasma reactor facilitates the growth of the rutile phase during the synthesis of TiO 2 from titanium nitride. Characteristic Raman bands of the TiO 2 rutile were detected at 147, 236, 447, and 611 cm -1 in the powders synthesized at low oxygen flow rates.…”

Section: Resultsmentioning

confidence: 99%

“…It was shown in [14] that thermal processes in plasma are very efficient in the production of nanocrystalline materials on account their high temperature, high enthalpy, and high rate of hardening, which leads to homogeneous condensation of the gas phase. The reactor with a thermal rf plasma for the synthesis of pure rutile and anatase TiO 2 nanoparticles by oxidizing of titanium nitride powder were employed in [15]. However, this method requires the raw material of coarse-grained TiH 2 powder, thus complicating the process.…”

Section: Introductionmentioning

confidence: 99%

Influence of the oxygen concentration on the formation of crystalline phases of TiO2 during the low-pressure arc-discharge plasma synthesis

2016

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Abstract. The synthesis of titanium dioxide (TiO 2 ) nanoparticles with different percentage of anatase and rutile phases is investigated. The synthesis is performed by controlling the oxygen percentage in the gas mixture in the plasmachemical evaporation-condensation process employing a low-pressure arc discharge. In all our experiments, the pressure in the plasmachemical reactor and the average size of particles remain constant and are 60 Pa and 6 nm, respectively. The crystal structure of synthesized TiO 2 is studied using X-ray diffraction; the morphology of the particles is analyzed employing transmission electron microscopy. Using Xray phase analysis, it is established that the concentration of the TiO 2 anatase phase decreases upon a decrease in the oxygen concentration in the gas mixture. It is shown that the TiO 2 anatase phase is more efficient for photocatalytic decomposition of methylene blue than the rutile phase. IntroductionTitanium dioxide (TiO 2 ) is one of the most studied materials; it has many applications in industry and research, especially in photocatalysis [1,2]. A comprehensive review of the surface properties of TiO 2 , in which the interrelation between the structure and properties is emphasized, is given in [3]. The photoactivity of TiO 2 is pointed out in [4] as one of the most interesting and attractive properties. Experimental and theoretical investigations of the structural and electronic properties of TiO2 are described in [5]. TiO 2 can exist in a few stable crystalline forms the most widespread of which are anatase, rutile, and brookite [6]. The energy properties of TiO 2 polymorphs (relative to the rutile phase) was studied in [7], where it was found that they are lower by 0.71 kJ/mol for the brookite and are higher by 2.61 kJ/mol for the anatase. The brookite phase is stable only at very low temperatures and, therefore, is almost of no practical importance. The rutile and anatase phases usually coexist as mixed phases; that is why some efforts are necessary for obtaining the required pure phase. In recent years, the anatase phase of TiO 2 has aroused great interest owing to the technological applications in paints, pigments, and photocatalysis. It was reported that anatase has a higher photocatalytic activity than rutile [8]. Thus, the synthesis of TiO 2 with a preset crystalline phase on a large scale is of great practical importance. Although the chemical methods make it possible to obtain TiO 2 in large amounts [9], their structure, however, is mainly amorphous. It is shown in [10] that the presence of amorphous structure in TiO 2 reduces its photacatalytic activity and, consequently, the synthesis of nanocrystalline TiO 2 is an urgent problem. The results of chemical synthesis show that the time and the temperature of calcination greatly affect the TiO 2 nanopowder [11]. Although the phase transformations of TiO 2 during annealing of chemically synthesized TiO 2 have been studied by many researchers [12], the data on the temperatures in the reactions are controversial. Th...

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“…The Raman spectrum of the TiO2-coated a-silica tube by the OVD method is similar to the spectrum of the TiO2 nanopowders with 60 wt. % of anatase content [5,6].…”

Section: Characterizationmentioning

confidence: 99%

TiO2-Impregnated Porous Silica Tube and Its Application for Compact Air- and Water-Purification Units

et al. 2015

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A simple, convenient, reusable, and inexpensive air-and water-purification unit including a one-end sealed porous amorphous-silica (a-silica) tube coated with TiO2 photocatalyst layers has been developed. The porous a-silica layers were formed through outside vapor deposition (OVD). TiO2 photocatalyst layers were formed through impregnation and calcination onto a-silica layers. The resulting porous TiO2-impregnated a-silica tubes were evaluated for air-purification capacity using an acetaldehyde gas decomposition test. The tube (8.5 mm e.d. × 150 mm) demonstrated a 93% removal rate for high concentrations (ca. 300 ppm) of acetaldehyde gas at a single-pass condition with a 250 mL/min flow rate under UV irradiation. The tube also demonstrated a water purification capacity at a rate 2.0 times higher than a-silica tube without TiO2 impregnation. Therefore, the tubes have a great potential for developing compact and in-line VOC removal and water-purification units. OPEN ACCESSCatalysts 2015, 5 1499

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Preparation of pure rutile and anatase TiO2 nanopowders using RF thermal plasma

Cited by 96 publications

References 21 publications

A method for large-scale synthesis of Al-doped TiO₂nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

A method for large-scale synthesis of Al-doped TiO₂nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

Influence of the oxygen concentration on the formation of crystalline phases of TiO2 during the low-pressure arc-discharge plasma synthesis

TiO2-Impregnated Porous Silica Tube and Its Application for Compact Air- and Water-Purification Units

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Preparation of pure rutile and anatase TiO2 nanopowders using RF thermal plasma

Cited by 96 publications

References 21 publications

A method for large-scale synthesis of Al-doped TiO2nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

A method for large-scale synthesis of Al-doped TiO2nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

Influence of the oxygen concentration on the formation of crystalline phases of TiO2 during the low-pressure arc-discharge plasma synthesis

TiO2-Impregnated Porous Silica Tube and Its Application for Compact Air- and Water-Purification Units

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A method for large-scale synthesis of Al-doped TiO₂nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

A method for large-scale synthesis of Al-doped TiO₂nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding