Coating of anatase titania on clinoptilolite by metal organic chemical vapor deposition method: enhanced mesoporosity and photocatalytic activity (original) (raw)
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TiO2/clinoptilolite composites for photocatalytic degradation of anionic and cationic contaminants
Journal of Materials Science, 2013
The present work aims to study the bulk and surface properties of the TiO 2 /clinoptilolite composite on the crystalline structure, superficial area, bandgap energy, zeta potential, particle size distribution, and chemical composition; in order to analyze the effect of the clinoptilolite proportion in the photocatalytic degradation of pollutants. TiO 2 /clinoptilolite composites were prepared by adding different mass proportions of clinoptilolite to a solgel bath containing TiCl 4 as the titania precursor. Surface charge studies explain the larger sensitivity to composite ratio observed in the photocatalytic degradation of anionic pollutants than in cationic dyes. An optimum TiO 2 /clinoptilolite ratio of 90/10 was found to be the most efficient in terms of lower tendency to agglomeration, largest surface area, and increased crystallite size. Improvement in composite surface area occurs only at low clinoptilolite wt% and seems to be caused by lower agglomeration of nanometric TiO 2 and acid-induced porosity in the zeolite.
Environmental Science & Technology, 2008
Hybrid structured photocatalysts based on sepiolite, an adsorbent, and TiO 2 were prepared by extrusion of ceramic dough and conformed as plates. The influence of the photocatalyst configuration was studied either by including TiO 2 in the extrusion process (incorporated materials) or by coating the sepiolite plates with a TiO 2 film (coated materials). The influence of the OHsurface concentration in the photocatalytic performance was studied by treating the ceramic plates at different temperatures. The samples were characterized by N 2 adsorption-desorption, MIP, SEM, XRD, and UV-vis-NIR spectroscopy and tested in the photocatalytic degradation of trichloroethylene (TCE) as a target VOC molecule. Most of the catalysts presented high photoactivity, but considerable differences were observed when the CO 2 selectivity was analyzed. The results demonstrate that there is a significant effect of the catalyst configuration on the selectivity of the process. An intimate contact between the sepiolite fibers and TiO 2 particles for incorporated materials with a corncob-like structure favored the migration of nondesirable reaction products such as COCl 2 and dichloroacetyl chloride (DCAC) to the adsorbent, reacting with OHgroups of the adsorbent and favoring the TCE mimeralization.
RSC Advances, 2021
TiO 2-supported clinoptilolite (TiO 2 /CP) was synthesized in the presence of F À ions. Various characterizations demonstrated that the particle size of loaded TiO 2 increased linearly with an increase in the temperature and concentration of F À ions. In particular, the additive F À ions were favored to produce the mutually independent co-exposed {001} and {101} facets of loaded TiO 2 , while TiO 2 /CPs synthesized in the absence of F À ions were dominated by the thermodynamically stable {101} facet. As photocatalysts for the removal of crystal violet or methyl orange dyes under UV-irradiation in aqueous solutions, TiO 2 / CPs (ACP6) synthesized in the presence of F À ions significantly improved the degradation efficiency, as compared to ACP3 obtained in the absence of F À ions. These results elucidated that the highly energetic {001} exposed facet, large particle size and fine dispersion of loaded TiO 2 in TiO 2 /CP accounts for its best photocatalytic performance. The effected mechanism of operational parameters on the degradation performances is proposed.
Separation and Purification Technology, 2017
Clinoptilolite supported rutile TiO 2 composites were synthesized for the enhancement of its photocatalytic performance in the degradation of the aqueous terephthalic acid solution under UVC illumination by the increase in its surface area and to simplify its recovery from the treated solution after use. The XRD spectra of the composites revealed the formation of pure rutile TiO 2 on the surface of the clinoptilolite. The SEM images showed the formation of the spherical TiO 2 clusters were composed of nano fibers on the surface of the clinoptilolite. For all composites synthesized, the dispersion of the TiO 2 particles on the clinoptilolite led to a surface area larger than that of the bare TiO 2 and clinoptilolite. The materials synthesized in the present study exhibited higher catalytic activity compared with the commercial Degussa P25 and anatase. Among the catalysts synthesized the TiO 2 /clinoptilolite with a weight ratio of 0.5 was found to be the most photoactive catalyst even though it contains a lesser amount of active TiO 2. The kinetic of the reactions for different catalyst was found to be consistent with the pseudofirst order kinetic model. The results of the Langmuir-Hinshelwood model showed the slight contribution of the adsorption on the degradation. The activity of the TiO 2 /clinoptilolite with a weight ratio of 0.5 decreased after repetitive use due to the accumulation of the TPA molecules on the surface of the catalyst.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2003
The degradation of 2-chlorophenol (2-CP) was investigated by a combination of TiO 2 -based photocatalysis and adsorption. Three combined systems were compared: (i) TiO 2 was intercalated into the interlamellar space of a hydrophilic montmorillonite by means of a heterocoagulation process (TiO 2 pillared montmorillonite, TPM); (ii) TiO 2 was hydrothermally crystallized on hexadecylpyridinium chloride-treated montmorillonite (HDPM-T); (iii) hexadecylpyridinium chloride-treated montmorillonite (HDPM) was used as adsorbent and Degussa P25 TiO 2 as photocatalyst (HDPM/TiO 2 ).
Chemical Industry and Chemical Engineering Quarterly, 2016
The titanium dioxide (TiO2) nanopowders were produced by sol-gel technique from tetrabutyl titanate as a precursor by varying some parameters of the sol-gel synthesis like the temperature (500 and 550 ?C) and the duration of the calcination (1.5, 2, and 2.5 h). X-ray powder diffraction (XRPD) results have shown that all synthesized nanopowders are dominantly in anatase phase, with the presence of a small amount of rutile in samples calcined at 550 ?C. According to the results obtained by Williamson-Hall method, the anatase crystallite size was increased with the duration of the calcination (from 24 to 29 nm in samples calcined at lower, and from 30 to 35 nm in samples calcined at higher temperature). The analysis of the shift and linewidth of the most intensive anatase Eg Raman mode confirmed the XRPD results. The analysis of pore structure from nitrogen sorption experimental data described all samples as mesoporous, with mean pore diameters in the range of 5-8 nm. Nanopowder proper...
International Journal of Engineering Research and Technology (IJERT), 2015
https://www.ijert.org/preparation-and-characterization-of-different-tio2-modified-montmorillonite-meso-microporous-materials-with-enhanced-photocatalytic-activity https://www.ijert.org/research/preparation-and-characterization-of-different-tio2-modified-montmorillonite-meso-microporous-materials-with-enhanced-photocatalytic-activity-IJERTV4IS090260.pdf A set of TiO2-modified montmorillonite meso-microporous materials, as photocatalysts, was successfully prepared in different ways and evaluated by the photodegradation of 4-nitrophenol (4-NP) in water, since it is a recalcitrant organic pollutant. The effects of photocatalysts' preparation methods on their textural, structural and catalytic properties were tested. To understand the relationship between the photocatalysts structure and performance, these were characterized by X-Ray Diffraction (XRD), UV-spectroscopy, Scanning Electron Microscopy/Energy Dispersive X-ray spectroscopy (SEM/EDX), Fourier Transform Infrared Spectroscopy (FTIR), X-ray fluorescence (XRF), specific surface area and porosity measurements. A high specific surface area (up to 231 m 2 /g), a meso-microporous structure and a high stability have been found for the TiCl4-M and TiCl3-M prepared photocatalysts. In addition, to improve the 4-NP degradation, various parameters' effect was studied such as the type of the photocatalyst, its amount loading, the pH of the 4-NP solution and the initial 4-NP concentration. Then, the 4-NP degradation rate has reached 99% only when Anatase Titanium dioxide was supported on montmorillonite, at pH=5, with 0.2 g/100 mL of photocatalyst (TiCl4-M or TiCl3-M) amount and a 4-NP concentration equal to 20 mg.L-1 .
2012
Several types of titania-based photocatalysts were prepared by the thermal decomposition of metatitanic acid. The obtained photocatalysts were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and thermal analysis. The photoreduction of potassium dichromate was used as a model reaction in order to evaluate the photocatalytic activity of the prepared catalysts. The influence of methanol on the rate of photoreduction was also investigated. It was determined that the most active catalyst is obtained during annealing of metatitanic acid at 400 °C and contains 69.3% of rutile and 30.7% of anatase. Cr(VI) adsorption is best described by the Langmuir adsorption isotherm. Titania catalyst modified with copper, cobalt, zinc or tungsten additives has larger adsorption capacity for Cr(VI), but smaller photoreduction rate as compared to pure TiO 2 .
Journal of Solid State Chemistry, 2009
Mesoporous TiO 2 -CeO 2 nanopowders responding to visible wavelength were synthesized by using a surfactant assisted sol-gel technique. They were obtained using metal alkoxide precursors modified with acetylacetone (ACA) and laurylamine hydrochloride (LAHC) as surfactant. The samples were characterized by XRD, nitrogen adsorption isotherm, SEM, TEM, and selected area electron diffraction (SAED), respectively. The 95 mol% TiO 2 -5 mol% CeO 2 system yielded single anatase phase, however, further addition of the CeO 2 formed cubic CeO 2 structure while anatase TiO 2 decreased. Additions of 5 and 10 mol% CeO 2 increased the surface area, but those of 25, 50, and 75 mol% CeO 2 did not affect it very much. By using this mixed metal oxides system, TiO 2 can be modified to respond to the visible wavelength. The mixed metal oxides had catalytic activity (evaluating the formation rate of I 3 À ) about 2-3 times higher than pure CeO 2 , while nanosize anatase type TiO 2 materials had no catalytic activity under visible light. The catalytic activity was almost proportional to the specific surface area. The formation rate of I 3 À was much improved by changing the calcination temperature and calcination period. Highest catalytic activity in this study was obtained for the 50 mol% TiO 2 -50 mol% CeO 2 nanopowders calcined at 250 1C for 24 h. r 2004 Elsevier Inc. All rights reserved.