Photocatalytic degradation of alprazolam in water suspension of brookite type TiO2 nanopowders prepared using hydrothermal route (original) (raw)
Photocatalytic activity of nanocrystalline TiO2 (brookite, rutile and brookite-based) powders
The metastable phase of TiO2(B), one of the polymorphs of titanium dioxide (TiO2), was prepared by a hydrothermal treatment of a titanium glycolate complex ([Ti4(C2H2O3)4(C2H3O3)2(O2)4O2] 6-) at 473 K for 1-72 h in the presence of H2SO4. Characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed that the obtained samples were composed of single phase TiO2(B) and the particles had plate-like morphology. After post-synthetic hydrothermal crystal growth (PHCG) applied to the as-prepared sample, thicker plate-like shaped particles were obtained. The photocatalytic activities of the samples obtained by the hydrothermal treatment and after the subsequent PHCG were evaluated in terms of methanol decomposition.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2008
Nanocrystalline TiO 2 powders were synthesized by thermohydrolysis of TiCl 4 in HCl or NaCl aqueous solutions. Rutile, mixtures of brookite and rutile or mixtures of anatase, brookite and rutile were obtained depending on the acidity of the medium. Crystalline phases and composition of the mixtures were identified by using XRD analysis. Pure brookite nanoparticles, separated from the mixtures of brookite and rutile by simple peptization with water, were stable against transformation to rutile up to 750 • C. The prepared TiO 2 powders were characterized by thermal analysis, diffuse reflectance spectroscopy and BET surface area determinations. The band gap of bulky brookite was estimated 3.29 eV. 4-Nitrophenol photodegradation was used to evaluate the photocatalytic activity of the various samples. The highest activity corresponded to the powders consisting of more than one crystalline phase.
Catalysis Letters, 2000
Nanocrystalline brookite-type titanium(IV) oxide (TiO 2 ) powder was synthesized by solvothermal treatment of oxobis(2,4-pentanedionato-O,O')titanium in a 1,2-ethanediol-water system in the presence of sodium acetate followed by hydrothermal treatment at 373 K in order to remove organic moieties contaminating the powder. The powder was calcined at various temperatures to change its physical properties and then used for three types of photocatalytic reaction: mineralization of acetic acid (AcOH) in an aerated aqueous suspension of bare TiO 2 powder, evolution of molecular hydrogen from 2-propanol in an aqueous suspension of in situ platinized powder, and formation of molecular oxygen (O 2 ) from silver sulfate in a deaerated aqueous suspension of bare TiO 2 powder.
Materials Letters, 2006
Transparent nanocrystalline pure anatase titania (nano-TiO 2 ) was synthesized by hydrothermal process at 200 -C. Photocatalytic activity of the nano-TiO 2 as in the form of sol was tested for degradation of Methylene Blue (MB) and Reactive Red 120 (RR-120) in aqueous solutions. Structural and physico-chemical properties of the nano-TiO 2 were characterized using powder XRD, SEM, BET, FT-IR and elemental analyses. Complete photodegradation of RR-120 was successfully achieved by aid of the nano-TiO 2 whereas MB was not degraded, maybe because of reversible color change in nano-TiO 2 sol/MB mixture after the UV irradiation was stopped. Potocatalytic activity of the synthesized the nano-TiO 2 for degradation of RR-120 was compared with Degussa P-25 at optimum conditions determined for RR-120. It was found that the nano-TiO 2 can be repeatedly used with higher photocatalytic activity than Degussa P-25. D
Materials Science in Semiconductor Processing, 2012
TiO 2 nanoparticles were prepared using a surfactant (linoletic acid (LA) or polyethylene glycol-400 (PEG-400)) at various hydrolysis ratios (R¼ H 2 O/C 2 H 5 OH) by the hydrothermal method and studied for photocatalytic degradation of rhodamine B (RhB) under visible light irradiation. Special shapes of TiO 2 nanoparticles, such as cubic, hexagon, bipyramid, and bullet, were found from the use of PEG-400 during the preparation. The cause for the formation of these special shapes is also discussed here. Interestingly, the hydrolysis ratios affected the Brunauer-Emmett-Teller (BET) special surface areas of the TiO 2 nanoparticles. Owing to the effects of the surfactant PEG-400 on the microstructures, the resulting materials exhibited relatively higher photocatalytic activity than conventional TiO 2 nanoparticles in the presence of LA. Furthermore, P-TiO 2-8/10 (P is PEG-400 and 8/10 is H 2 O/C 2 H 5 OH molar ratio) nanoparticles had a similar photocatalytic activity to P25 and TiO 2-10/10.
Desalination, 2011
In the present study, titanium dioxide nanoparticles were synthesized by sol-gel method, from various precursors in some solvents under different synthesis conditions such as solvent percent, water percent, reflux temperature, reflux time, sol drying method and calcination temperature. Structure, size, band gap and specific surface area of nanoparticles were determined by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis reflectance spectroscopy (DRS) and BET analysis methods. The photocatalytic activity of TiO 2 was evaluated in the photodegradation of C.I. Acid Red 27 as a model contaminant from textile industry under UV-C light irradiation. Results indicate that structure and photocatalytic activities are functions of precursor type, solvent type and other synthesis conditions. TiO 2 nanoparticles synthesized in the presence of methanol as solvent and titanium (IV) isopropoxide as precursor under 3 h reflux at 80°C with sol thermal drying and calcination temperature of 450°C indicate high photocatalytic activity in comparison with TiO 2 -P25 (Degussa Co.).
Advances in Natural Sciences: Nanoscience and Nanotechnology, 2017
In the present work, nano-sized TiO 2 polymorphs (anatase, brookite, and rutile) were synthesized via hydrothermal treatment of an amorphous titania. Three polymorphs were characterized by XRD, Raman spectroscopy, SEM, UV-Vis DRS, and N 2 -sorption measurements. The photocatalytic degradation experiments were performed with low catalyst concentration, high organic loading under a 60 W UV-Vis solarium lamp irradiation. The photocatalytic degradation was monitored by UV-Vis spectroscopy and TOC measurements. Cinnamic acid, ibuprofen, phenol, diatrizoic acid and the dyes rhodamine B and rose bengal were used as model pollutants. The formation of intermediates was studied by ESI-TOF-MS measurements. The presence of active species was checked by quenching the activity by addition of scavengers. The photocatalytic activity decreased in the order: anatase ⩾ brookite > rutile, with growing recalcitrance of organic compounds. The differences in the activity are more pronounced in the degree of mineralization. The valence band holes and superoxide radicals were the major active species in the photocatalytic treatment with anatase and brookite, whereas hydroxyl radicals and superoxide radicals contributed mainly in the treatment with rutile explaining the lower activity of rutile. The complementary use of UV-Vis spectroscopy and TOC measurements was required to obtain a comprehensive realistic assessment on the photocatalytic performance of catalyst.
Journal of Colloid and Interface Science, 2015
TiO 2 photocatalysts with a mixture of different TiO 2 crystal polymorphs have customarily been synthesized hydrothermally at high temperatures using complicated and expensive equipment. In this study TiO 2 nanoparticles with a mixture of TiO 2 crystals were synthesized using a modified sol-gel method at low temperature. In order to form nanoparticles with different polymorphs a series of samples were obtained at pH 2, 4, 7 and 9. Raw samples were calcined at different temperatures ranging from 200 to 800°C to evaluate the effect of the calcination temperature on the physico-chemical properties of the samples. XRD results revealed that a mixture of anatase and brookite can be obtained in the as-synthesized samples and in those calcined up to 800°C depending on the pH used to obtain the final product. Indeed, a mixture of anatase brookite and rutile; or a sample with only rutile phase can be yielded through further calcination of the as-prepared samples at temperatures P600°C due to phase transformation. The photocatalytic performance of the samples with a mixture of anatase-brookite; anatasebrookite-rutile; and anatase-rutile (Degussa P25 TiO 2) was exquisitely investigated in the degradation of methylene blue solutions. The samples obtained at pH 2 and calcined at 200°C possessed the highest activity of all due to its superior properties. This study elucidates a facile method suitable for the synthesis of TiO 2 with different mixtures of TiO 2 polymorphs with desirable properties for various applications.
Applied Catalysis A: General, 2012
TiO 2 nanoparticles have been prepared by sol-gel precipitation and further hydrothermal treatment. In this way, the effect of the hydrothermal treatment on the structural properties and photocatalytic activity of sol-gel synthesized catalysts has been investigated. These catalysts have been produced by hydrolysis of a mixture of isopropanol-titanium tetraisopropoxide (iPrOH-TiiP). The prepared photocatalysts were characterized by means of X-ray diffraction (XRD), surface area analysis (BET), transmission microscopy (TEM), thermogravimetric analysis (TG), scanning electron microscopy (SEM) analysis, diffuse reflectance, sedimentability analysis and aggregate size study. Besides, the structural evolution with the temperature of the photocatalysts treated or not hydrothermally was studied. It was observed that the calcination produces approaching between the characteristics of both sets of photocatalysts. The photocatalytic activity of the obtained photocatalysts was investigated, using phenol as a model pollutant. The calcination temperature is the most remarkable factor that can affect the ultimate photocatalytic activity of the prepared photocatalysts. However, the hydrothermal treatment previous to calcination led to obtain photocatalysts which exhibit larger photocatalytic activity than their homologous photocatalysts without hydrothermal treatment. The obtained photocatalyst TiO 2 ht600 exhibits the same photocatalytic activity per surface area than the commercial TiO 2 Degussa P25 but with much faster sedimentability.
Adsorption Science & Technology, 2022
This paper investigates the use of A. vera extract as a natural capping agent for TiO 2 nanoparticles as well as a reducing agent for TiO 2 nanoparticles. XRD, ultraviolet diffuse reflectance (UV-DRS), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDXA) were used to characterize the material. In their X-ray diffraction patterns, the titanium dioxide nanoparticles were found to have a high degree of crystallinity, indicating that they were synthesized. Infrared (FT-IR) spectra were used to determine the chemical composition of the plant extract. The DRS spectra in the UV-visible range reveal a high absorption peak at 356 nm, which indicates the existence of TiO 2 nanoparticles in the sample. Shape of nanoparticles was revealed by SEM and TEM morphological investigations, which revealed their irregular and somewhat spherical nature. Only titanium and oxygen compounds were found in the EDX spectrum, indicating that they were present. This demonstrates that the NPs that were produced are devoid of contaminants. Using the produced nanoparticles as catalyst, we presented a photocatalytic degradation method for the dye methylene blue in this paper. The findings showed that 94 percent of the damage occurred within 120 minutes of being exposed to UV radiation.