Photocatalytic Denitrification of Nitrate Using Fe-TiO2-Coated Clay Filters (original) (raw)
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TiO2 Immobilized on Fibrous Clay as Strategies to Photocatalytic Activity
Materials Research, 2020
TiO 2 immobilized in Sepiolite (TiO 2 /Sep) was successfully prepared by the sol-gel technique, with titanium isopropoxide as the precursor for the formation of TiO 2 in the anatase phase calcined at 400 °C. The prepared samples were characterized by X-ray diffraction, Fourier Transform Infrared spectroscopy, Scanning Electron Microscopy coupled to energy dispersive spectroscopy, and thermogravimetric analysis. The results showed that TiO 2 /Sep structure was identified in all characterizations, showing the specific peaks, bands, mass loss, and morphology after the impregnation process. Photocatalytic experiments were performed under UV irradiation with various photocatalyst concentrations and pH effects in the reaction. The prepared samples presented 72% photocatalytic efficiency for eosin (EA) dye discoloration after 150 min under UV light. This efficiency was attributed to the radicals generated from the TiO 2 and the high specific surface area, showing that TiO 2 /Sep is promising candidate in the degradation of organic pollutants.
Synthesis and characterisation of clay-supported titania photocatalysts
Journal of colloid and interface science, 2007
Titanium dioxide (TiO 2 ) has been extensively investigated as a photocatalyst for environmental remediation, as it is photostable, nontoxic, highly reactive and is a relatively inexpensive material [1], [2], [3], [4] and [5]. When TiO 2 is illuminated by UV light (λ less-than-or-equals, slant ...
Structural refinement and photocatalytic activity of Fe-doped anatase TiO2 nanoparticles
Colloidal iron-doped (0.0-3.0 mol%) TiO 2 nanoparticles have been synthesized using sol-gel method and characterized by thermogravimetric analysis, powder XRD, IR spectroscopy, Raman spectroscopy, and transmission electron microscopy (TEM). The characteristic features of nanocrystalline TiO 2 in tetragonal anatase phase were confirmed by powder XRD studies with Rietveld refinement. Rietveld refinement data gave 2.59, 3.21 value of R B for pure TiO 2 and 3.0 mol% Fe:TiO 2 nanoparticles, respectively. Raman bands at 639 cm −1 , 517 cm −1 , and 395 cm −1 further confirmed the pure anatase phase in all samples. TEM pictures revealed the non-spherical nanoparticles having sizes in between 7 and 14 nm. Surface area and pore volume for the samples were in the range of 150-87 m 2 /g and 0.35-0.21 cm 3 /g, respectively. The magnetic and optical properties of the nanoparticles were investigated by using SQUID magnetometer and UV-vis spectroscopy. The undoped titania nanoparticles were diamagnetic; whereas all doped titania samples were paramagnetic. The optical band gap of titania nanoparticles were found to decrease with the increase in iron content in host lattice. The photocatalytic performance of the iron-doped TiO 2 nanoparticles for the conversions of p-nitrobenzaldehyde to p-nitrobenzoic acid as well as photodegradation of Rhodamine 6G was also investigated.
ACS Omega
High-purity (98.8%, TiO 2) rutile nanoparticles were successfully synthesized using ilmenite sand as the initial titanium source. This novel synthesis method was cost-effective and straightforward due to the absence of the traditional gravity, magnetic, electrostatic separation, ball milling, and smelting processes. Synthesized TiO 2 nanoparticles were 99% pure. Also, highly corrosive environmentally hazardous acid leachate generated during the leaching process of ilmenite sand was effectively converted into a highly efficient visible light active photocatalyst. The prepared photocatalyst system consists of anatase-TiO 2 /rutile-TiO 2 /Fe 2 O 3 (TF-800), rutile-TiO 2 /Fe 2 TiO 5 (TFTO-800), and anatase-TiO 2 /Fe 3 O 4 (TF-450) nanocomposites, respectively. The pseudo-second-order adsorption rate of the TF-800 ternary nanocomposite was 0.126 g mg −1 min −1 in dark conditions, and a 0.044 min −1 visible light initial photodegradation rate was exhibited. The TFTO-800 binary nanocomposite adsorbed methylene blue (MB) following pseudo-second-order adsorption (0.224 g mg −1 min −1) in the dark, and the rate constant for photodegradation of MB in visible light was 0.006 min −1. The prepared TF-450 nanocomposite did not display excellent adsorptive and photocatalytic performances throughout the experiment period. The synthesized TF-800 and TFTO-800 were able to degrade 93.1 and 49.8% of a 100 mL, 10 ppm MB dye solution within 180 min, respectively.
Applied Catalysis A: General, 2010
Porous TiO 2-anatase thin films were obtained by sol-gel method using dip-coating procedure onto glassslides and silicon wafers in order to study the effect of the porous structure on the photocatalytic properties. Titania sols were synthesized using titanium isopropoxide (TISP) with two types of complexant molecules (acetyl-acetone (AcAc) or acetic acid (AcOH)) and different types of pore-generating agents as: Pluronic F127 (F127), cetyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), polyethylene glycol hexadecyl ether (Brij56, Brij58). The coatings were characterised by different techniques as grazing X-ray diffraction (GXRD), spectral ellipsometry, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Maximum thickness around 280 nm, and refractive index as low as 1.68 were obtained, indicating that the surfactants allow obtaining porous films. GXRD and TEM analysis confirm the presence of a porous structure but not ordered. TiO 2 films obtained from AcAc or AcOH with Brij58 and F127 sols present specific surface areas between 28 and 68 m 2 /g. Photocatalytic activity was studied through the degradation of methyl orange in aqueous solution under UV light exposure. Methyl orange degradation increases with the film thickness up to a maximum value of 470 nm, beyond which the efficiency does not further increase. The photocatalytic activity depends on different parameters, such as porosity, film thickness and total surface exposed to illumination.
Synthesis, structure and photocatalytic properties of Fe(III)-doped TiO2 prepared from TiCl3
Applied Catalysis B: Environmental, 2008
Iron(III)-doped titanium dioxide photocatalysts were prepared from aqueous titanium(III) chloride solution in the presence of dissolved FeCl 3 (0-10.0 at.% relative to TiCl 3 ) by co-precipitation method. The precipitate was completely oxidized in the aerated suspension, hydrothermally treated, washed and calcinated. The structure of the powders was characterized by thermoanalysis (TG-DTA), diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), nitrogen adsorption and transmission electron microscopy (TEM). The light absorption of the iron-containing powders is red shifted relative to the bare sample. The particle size and anatase content were found to significantly decrease at iron contents !6.0 at.% which is accompanied with the increase of their specific surface area. XANES measurements showed that the local structure of iron systematically changes with the variation of the dopant concentrations: at higher Fe-contents, hematite-or goethite-like environments were observed, consistent with the formation of separate X-ray amorphous Fe(III)-containing phases. The local structure of iron gradually transformed with decreasing dopant concentrations, possibly due to substitution of Fe(III) in the titania (TiO 2 ) crystal lattice. Energy dispersive X-ray analysis (EDX) and chemical analysis was used to characterize the iron content of the samples in the bulk and X-ray photoelectron spectroscopy (XPS) in the surface layer of the particles. The photocatalytic performance of the prepared photocatalysts was compared with the activity of Aldrich anatase under UV-vis and VIS irradiation in two different photoreactors. Maximum photocatalytic performance was found at 3.0 at.% iron concentration for UV-vis and at 1.2 at.% for VIS irradiation. Doping with iron(III) ions increased the photodegradation rate of phenol by a factor of three for UV-vis irradiation and by a factor of two for VIS irradiation, relative to the bare photocatalyst. #
Optimized Nanostructured TiO2 Photocatalysts
Frontiers in Materials, 2016
Titania is the most widely studied photocatalyst. In its mixed-phase configuration (anatase-rutile form)-as manifested in the commercially available P25 Degussa materialtitania was previously found to exhibit the best photocatalytic properties reported for the pure system. A great deal of published research by various workers in the field has not fully explained the underlying mechanism for the observed behavior of mixed-phase titania photocatalysts. One of the prevalent hypotheses in the literature that is tested in this work involves the presence of small, active clusters of interwoven anatase and rutile crystallites or "catalytic 'hot-spots'." Therefore, non-woven nanofibrous mats of titania were produced, and upon calcination, the mats consisted of nanostructured fibers with different anatase-rutile ratios. By assessing the photocatalytic and photoelectrochemical properties of these samples, the optimized photocatalyst was determined. This consisted of TiO2 nanostructures annealed at 500°C with an anatase/rutile content of 90/10. Since the performance of this material exceeded that of P25 complete structural characterization was employed to understand the catalytic mechanism involved. It was determined that the dominant factors controlling the photocatalytic behavior of the titania system are the relative particle size of the different phases of titania and the growth of rutile laths on anatase grains which allow for rapid electron transfer between the two phases. This explains how to optimize the response of the pure system.