Calcined TiO2 Research Articles

Synthesis, characterization and antifungal potential of titanium dioxide nanoparticles against fungal disease (Ustilago tritici) of wheat (Triticum aestivum L.)

Nanoparticles (NPs) preparation using a green as well as environmentally acceptable processes has achieved a lot of attention in recent decade. The current study compared the synthesis of titania (TiO2) nanoparticles synthesized from leaf extracts of two plant species (Trianthema portulacastrum, Chenopodium quinoa) and traditional approach by chemical preparation. The effects of no calcination on the physical characteristics of TiO2 NPs as well as their antifungal effects were examined and compared with the already reported calcinated TiO2 NPs. The produced TiO2 NPs were evaluated using high-tech techniques such as X-ray diffraction (XRD), scanning electron microscope, energy dispersive spectroscopy (EDX), and elemental mapping. TiO2 NPs prepared by sol-gel technique (T1) and prepared from extractions from leaves of T. portulacastrum (T2), and C. quinoa (T3) were either calcinated or non calcinated and tested against fungal disease (Ustilago tritici) of wheat for antifungal efficacy. The -peak (2θ) at 25.3 was confirmed by XRD to be connected with the anatase (101) form in both cases but before calcination, NPs were lacking the rutile and brookite peaks. The results showed that all types of TiO2 NPs examined had good antifungal activity against U. tritici, but those made from C. quinoa plant extract have good antifungal activity against disease. TiO2 NPs which are produced by the green methods (T2, T3) have the highest antifungal activity (58%, 57% respectively), while minimal activity (19%) was recorded when NPs were synthesized using the sol-gel method (T1) with 25 μl/mL. Non calcinated TiO2 NPs have less antifungal potential than calcined TiO2 NPs. It can be concluded that calcination may be preferred for efficient antifungal activity when using titania nanoparticles. The green technology may be used on a larger scale with less damaging TiO2 NP production and can be utilized against fungal disease on wheat crop to reduce crop losses worldwide.

High-temperature treated TiO2modified with 3-aminopropyltriethoxysilane as photoactive nanomaterials

AbstractA series of titanium dioxide (TiO2) modified with 3-aminopropyltriethoxysilane (APTES) was prepared by high-temperature calcination in an argon atmosphere in the temperature range from 800 to 1,000°C. The properties of the obtained samples were compared with those of pure TiO2annealed under the same conditions. Examining electron paramagnetic resonance (EPR) parameters at room temperature for APTES–TiO2showed an intense resonance line from defects related to conducting electrons withgefffrom 2.0028 to 2.0026 and 1.9052 for temperatures 800, 900, and 1,000°C, respectively, while for pure calcined TiO2, these ERP lines were not observed. With the increase in the calcination temperature to 900°C for APTES–TiO2samples, the EPR increases linearly. This has been combined with a relatively high anatase content and small crystallites. The EPR line intensity at RT calculated for 1 g of sample showed an almost linear relationship with the photoactivity in removing ORANGE II dyes from water.

TiO2 nanofibers fabricated by electrospinning technique and degradation of MO dye under UV light

Abstract Titanium dioxide (TiO2) nanofibers were synthesized by electrospinning to optimize the photocatalytic action efficiency. The synthesis of the fibers was carried out at four different wt% concentrations: 8, 9, 10 & 11% of polymer polyvinylpyrrolidone (PVP). The TiO2 fibers were further calcined at 700 °C to get powder form. The uncalcinated and calcined TiO2 nanofibers were characterized by using X-Ray diffraction (XRD), Raman spectroscopy, Scanning electron microscopy (SEM) and UV-Visible spectroscopy. Raman spectroscopy confirmed the rutile phase of the calcined TiO2nanofibers in powder form with a crystallite size of 34–38 nm. The surface morphology of the uncalcinated and calcined TiO2 nanofibers was examined by SEM and the fiber diameter found to be 360–540 nm. The optical bandgap of the calcined TiO2 nanofibers was found in the range of 3.29–3.24 eV. The photocatalytic activity of the TiO2 nanofibers as examined for uncalcinated and calcined nanofibers, methyl orange (MO) dye degraded up to 98 and 78%, respectively in 180 min under the exposure of UV light. Uncalcinated TiO2 nanofibers were found more suitable for degradation of MO dye as compared to calcined nanofibers.

Synthesis of Monolithic TiO2 Aerogels With Relatively Low Shrinkage and Improved Formability Assisted by CTAB

Monolithic TiO2 aerogels without severe shrink were obtained by the sol-gel method with the addition of the surfactant cetyltrimethylammonium bromide (CTAB) to control the hydrolysis and polycondensation process and acetonitrile solvent as the solvent to improve the crystallinity. After CO2 supercritical drying, the shrinkage ratio of monolithic TiO2 aerogels modified by CTAB decreased by up to ∼26.9%, compared with the pure TiO2 aerogel. Their apparent densities were all lower than 300 g/cm3. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform infrared spectroscopy (FTIR) and BET Specific Surface Area Analysis were used to analyze the as-synthesized samples. The results revealed that all the samples were anatase-TiO2 phase with nanoporous network structures. The specific surface areas reached 250.2 m2/g confirmed by the BET (Brunaur–Emmett–Teller method) analysis. However, TiO2 aerogels without the addition of CTAB showed evident agglomeration and collapse of the network in comparison with CTAB-added samples. To further study the structure-property relationship, the photocatalysis performance of as-synthesized and 300°C-calcined aerogels was carried out contrastively. Interestingly, the influences of the CTAB adding amount of as-synthesized and calcined TiO2 aerogels are negative and positive, respectively, which is probably due to the synergistic effect of CTAB hindrance and grain refinement. Potentially, This kind of TiO2 aerogels assisted by CATB with low density, small shrinkage, improved formability, high specific surface area and fine crystalline grain may be applied in various applications, such as electrochemistry, photocatalysis, etc.

Morphological Characterization of Selected Natural and Calcined TiO2 Photocatalysts Using SEM, XRD and BET

The present work characterized commercial TiO2 powder photo-catalysts (P25, AV01, S7001, PC100 & PC500) using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and Brauner, Emmer and Teller (BET) techniques to determine crystalline size(nm), particle size(nm) and specific surface area(m2/g) of natural and calcined TiO2 catalyst particles. TiO2 particulate layers were prepared by deposition from aqueous TiO2suspensions c=10g.L-1 on degreased microscopic glass of dimensions 75mm × 25mm calcined at 300°C for 2hrs. The calcined layers were scanned to obtain cross-sectional images and reveal particle size and catalyst morphology. The results indicate a crystalline/surface area ratio as follows; [(P25=28nm/50m2/g); (AV01=169nm/10m2/g); (S7001=9nm/250m2/g) ;(PC100=198nm/79.5m2/g) ;(PC500=173.6nm/91.3m2/g)]. Particle size of AV01 powder catalyst (100-150 nm) was larger compared to the other catalysts., catalyst P25, PC100, PC500 and S7001 appear to have almost similar particle sizes of between (50-100 nm). Comparing the observed particle sizes using the SEM technique with those calculated using XRD, it can be concluded that these values are very similar. X-Ray Diffraction patterns indicated that the crystalline structure AV01, S7001, PC100 and PC500 comprises of pure anatase phase. Catalyst P25 catalyst powder consisted of a crystal structure 74% anatase and 26% rutile content. Crystalline sizes were calculated by Scherer formula using a special programme Analytical X`pert.PRO + high score plus. It can be concluded that smaller crystalline size favours increased surface areas. An optimum balance between surface area and crystallinity is desirable to obtain maximum semi-conductor properties since the predominant electron/hole recombination depends on relative particle size/surface area ratios.

Assessment comparison of commercial TiO2 and TiO2 sol-gel on the degradation of caffeine using artificial radiation.

The presence of endocrine disrupting compounds in water receptor bodies, such as drugs, currently has in scientific field a great focus of studies focused on advanced water treatment techniques that enable the decontamination of water sources and public supply. In this context, this study focused on the characterization and evaluation of photocatalytic activity of catalysts calcined and uncalcined synthesized TiO2 and the commercial sol-gel route from caffeine degradation. The photocatalysts were characterized by N2 physisorption, X-ray diffraction, scanning electron microscopy (SEM/EDS), photoacoustic spectroscopy, and infrared spectroscopy (FTIR). They seek to evaluate the main textural, structural, chemical, and morphological differences that the method of synthesis can promote in obtaining a titanium oxide-based catalyst. Thus, the results of this study demonstrate that the synthesis method significantly influences the activity of the materials and that calcined TiO2 catalyst prepared using the sol-gel method has promising photocatalytic capabilities for the elimination of drugs such as caffeine when present in wastewater.

Deep Oxidative Desulfurization of Model fuels by Prepared Nano TiO2 with Phosphotungstic acid

In this study, nano TiO2 was prepared with titanium isopropoxide (TTIP) as a resource to titanium oxide. The catalyst was synthesized using phosphotungstic acid (PTA) and, stearyl trimethyl ammonium bromide (STAB) was used as the structure-directing material. Characterization of the product was done by the X-ray diffraction (XRD), X-ray fluorescent spectroscopy (XRF), nitrogen adsorption/desorption measurements, Atomic Force Microscope (AFM) and Fourier transform infrared (FTIR) spectra, were used to characterize the calcined TiO2 nanoparticles by STAB and PWA. The TiO2 nanomaterials were prepared in three crystalline forms (amorphous, anatase, anatase-rutile). The results showed that the nanoparticles of anatase TiO2 have good catalytic oxidative activity. This is because of the conversions of 100% within 90 sec from 300 ppm of dibenzothiophene. This is compared to conversion rates for anatase–rutile nanoparticles and amorphous nanoparticles which reached 52% and 31 %, respectively. The influence of the temperature of reaction, catalyst amount, H2O2 concentration, and initial DBT concentration on the oxidation of DBT was investigated.

Structural, optical and morphological properties of post-growth calcined TiO2 nanopowder for opto-electronic device application: Ex-situ studies

Nanocrystalline TiO2 powders have been selectively prepared by the simple combustion reaction method using urea as a fuel. The crystalline powder was obtained using a silica basin heated directly on a hot plate at 500 °C until self-ignition occurred. After combustion process, the calcined products were obtained by heating the as-prepared powders for 1 h in air atmosphere at various sintering temperatures [500–900 °C]. The obtained nanopowder materials were systematically characterized by X-day diffraction (XRD), micro-Raman, UV–visible absorption (UV–vis), and Fourier transform infrared (FT-IR) spectroscopics. Powder XRD pattern shows the good agreement rutile phase structured TiO2 and the sharp diffraction peaks indicates good for crystallinity. The size of a symmetry of the nanoparticles have been measured with aid of a scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), and Brunauer, Emmett and Teller (BET) surface studies. The crystallinity of the powders was found to increase with respect to calcination temperatures. The average specific surface area of the particle was probed using gas adsorption–desorption measurements. Raman spectroscopy experiment was performed to ascertain the nature of TiO2 powder quality. UV–vis absorption spectra results showed the changes in the absorption edges of TiO2 report to increasing the calcinations temperatures.

Preparation, characterization and photocatalytic performance of TiO2 prepared by using pressurized fluids in CO2 reduction and N2O decomposition

TiO2 photocatalyst was prepared unconventionally, using the sol–gel process controlled within the reverse micelles and the processing by pressurized hot fluids as an alternative to standard calcination. Conventional calcined TiO2 was prepared as well. Textural, microstructural and optical properties of prepared photocatalysts were characterized by using nitrogen physisorption, powder X-ray diffraction and DR UV–Vis spectroscopy. The photocatalytic properties of developed TiO2 catalysts were investigated in the photocatalytic reduction of CO2 and photocatalytic decomposition of N2O. It was revealed that TiO2 processed by pressurized hot fluids shows significantly improved textural properties and different crystallinity compared to its calcined analog. Yields of both reaction products (H2 and CH4) of CO2 photoreduction were higher for the extracted TiO2 photocatalyst. The same result was achieved in N2O photodecomposition. The maximum N2O conversion (83 % after 20 h of illumination) in inert gas was reached also over the TiO2 extracted photocatalyst, and it can be attributed to simultaneous N2O photocatalytic decomposition and N2O photolysis. Reaction kinetics of N2O-photoinduced decomposition was described well by the pseudo-first-rate law. The surface heterojunction of bicrystalline anatase–brookite phase corresponded to better catalytic activity of TiO2 processed by pressurized hot fluids in both reactions, in a consequence of reduced electron–hole pair recombination.

Elongated titania nanostructures as efficient photocatalysts for degradation of selected herbicides

Titanium dioxide nanotubes (TNT) were synthesized via hydrothermal method and calcined at various temperatures. The obtained calcined TiO2 nanomaterials with specific elongation orientation were characterized by transmission and scanning electron microscopy (TEM, SEM), X-ray diffraction (XRD), UV/Vis diffuse reflection spectroscopy (DRS), Laser Doppler electrophoresis (LDE) and their textural properties were evaluated. The photocatalytic activity of obtained nanopowders was evaluated considering photodegradation rate of herbicide clomazone, rarely studied herbicide. The influence of calcination temperature of catalysts with elongated morphology on their photocatalytic activity was evaluated. The best results were obtained with TNT annealed at 700°C, which can be assigned to the best balance between crystal structure, morphology and surface properties of nanoparticles induced by annealing. Also, the photocatalytic degradation rates of another two herbicides (picloram, and mecoprop) were compared, due to possibility that the efficiency of photocatalytic degradation is greatly influenced by the molecular structure. The mineralization degree of selected herbicides in the presence of TiO2 based photocatalysts was evaluated applying total organic carbon (TOC) measurements.

Room temperature synthesis of microemulsion mediated rutile TiO2nanoparticles showing remarkable photocatalytic activity

Abstract We report a simple low cost method at room temperature and normal pressure for the synthesis of mono-dispersed spherical rutile titania nanoparticles using the water in oil microemulsion process. The as-synthesized and calcined TiO2 nanoparticles were characterized by means of X-ray diffractometry, Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy and transmission electron microscopy. The effect of calcination temperature on the crystalline phase, particle size, specific surface area and surfactant concentration was studied in detail. As-synthesized rutile TiO2 nanoparticles showed remarkable photocatalytic activity for the degradation of methyl orange dye as a model pollutant. The reaction was found to follow first order kinetics. Chemical oxygen demand results show substantial degradation and mineralization of targeted dye.

TiO2 AND TiO<sub>2</sub>/ ACTIVE CARBON PHOTOCATALYSTS IMMOBILIZED ON TITANIUM PLATES

Study of TiO2 and TiO2 active carbon photocatalyst was done. Immobilization was carried out by sol-gel process using titanium diisopropokside bis-acetylacetonato as titanium precursor. The catalyst was characterized using XRD and SEM. The activity of catalyst was tested using 10 ppm of pentachlorophenol (PCP) as a model of organic waste. The test was done by irradiating PCP solution using UV lamp and varying the catalysts of TiO2, and TiO2/C of 8/2 and 5/5. About 5 mL of sample was taken out at interval time of 1, 2, 4, 6, 8 and 10 h iradiation followed by the measurement of PCP residue and chloride ions. From the characterization results it is known that calcined TiO2 andTiO2/C of 8/2 and 5/5 have anatase structure and active as a catalyst. The activity results using PCP as an organic waste showed that combination of TiO2 and active carbon would increase the activity of the catalyst, but at high percentage of active carbon the performance of the photocatalyst decreased. Keywords: catayist TiO2, catayist TiO2/active carbon, photocatalysis

Characterization of Pore Structure and Coordination of Titanium in TiO2 and SiO2–TiO2 Sol-Pillared Clays

Titania sol-pillared clay (TiO2 PILC) and silica–titania sol-pillared clay (SiO2–TiO2 PILC) were synthesized by the sol–gel method. Supercritical drying (SCD) and treatment with quaternary ammonium surfactants were used to tailor the pore structure of the resulting clay. It was found that SCD approach increased the external surface area of the PILCs dramatically and that treatment with surfactants could be used to tailor pore size because the mesopore formation in the galleries between the clay layers follows the templating mechanism as observed in the synthesis of MCM-41 materials. Highly mesoporous solids were thus obtained. In calcined TiO2 PILC, ultrafine crystallites in anatase phase, which are active for photocatalytic oxidation of organics, were observed. In SiO2–TiO2 PILCs and their derivatives, titanium was highly dispersed in the matrix of silica and no crystal phase was observed. The highly dispersed titanium sites are good catalytic centers for selective oxidation of organic compounds.