Surface modification of nano-TiO2 with lanthanide-acetylacetonate complexes

The surface modification of nano-TiO2 was carried out with lanthanide-acetylacetonate complexes by adsorption method. The effects of lanthanide complexes content, lanthanide element type, adsorption temperature, solvent dosage, adsorption time and other conditions on the photodegradation activity of methyl orange by the modified catalyst were studied, and suitable modification conditions were obtained. The results show that the photocatalytic activity of the modified nano-TiO2 is much higher than that of the unmodified pure TiO2, and the lanthanide-acetylacetonate complexes is an excellent surface modifier.

Facile fabrication of TiO2/Bi5O7Br photocatalysts for visible-light-assisted removal of tetracycline and dye wastewaters

The emergence of persistent organic pollutants such as dyes and pharmaceuticals in the aquatic environment has created drastic concerns worldwide due to their toxicity and potential hazards to the environment. Accordingly, non-stoichiometric TiO2/Bi5O7Br nanocomposites were prepared by stirring method as a visible-light-effective photocatalyst for degradation of amoxicillin (AMX) and tetracycline (TC), as antibiotic pollutants, and Rhodamine B (RhB), methylene blue (MB), and malachite green (MG), as dye pollutants. The physiochemical properties of the samples were studied using FESEM, TEM/HRTEM, XRD, EDX, UV–vis DRS, FT-IR, XPS, BET, PL, photocurrent, and EIS analyses. The TiO2/Bi5O7Br (40%) photocatalyst performed superior to TiO2, Bi5O7Br, and TiO2/BiOBr (40%) in photodegradation of the studied contaminants. The degradation rate constants of AMX, TC, MG, RhB, and MB over the TiO2/Bi5O7Br (40%) photocatalyst were 18.2‒32.5-folds greater than pure TiO2, 1.6‒17.3 times higher than pure Bi5O7Br, and 1.4‒13 times larger than TiO2/BiOBr (40%), respectively. Quenching studies showed that superoxide anion radicals and holes had major roles in photocatalytic elimination of TC. Importantly, TiO2/Bi5O7Br (40%) nanocomposite showed robust reusability with high degree of TC removal after four successive photocatalytic recycles. This research introduces a cost-effective, efficient, and reusable visible-light-triggered binary system based on TiO2 for decontamination of medicinal and dye polluted wastewaters.

Investigation of environmental and therapeutic applications of holmium doped titanium dioxide (Ho-TiO2) nanocatalysts. Kinetic and thermodynamic study of the photocatalytic degradation of Safranin O dye

Titanium dioxide (TiO2) and Holmium doped Titanium dioxide(Ho-TiO2) nanoparticles (NPs) were synthesized through Sol Gel method. The synthesized NPs were characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), Energy dispersive X-ray analysis (EDX), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Photoluminescence spectroscopy. DNA binding, antibacterial, hemolytic and antioxidant assays of the synthesized nanoparticles were also carried out for finding their therapeutic applications. Successful doping of TiO2 with Ho reduced the band gap from 3.10 to 2.88 eV. SEM and XRD analysis showed that both TiO2 and Ho-TiO2 NPs exhibit tetragonal structure and as a result of doping the morphology of the particles improved and agglomeration reduced. PL emission intensity of TiO2 also reduced with doping.The holmium doped TiO2 were used for the first time against the degradation of Safranin O dye, DNA binding study and biocompatibility assay.The degradation of Safranin O dye over both the catalysts followed first order kinetics. The calculated activation energies for the photo degradation of given dye were found to be 51.7 and 35.2 kJ/mol using TiO2 and Ho-TiO2 NPs respectively. At 180 minutes time interval 84 and 87% dye degradation was observed using pure TiO2 and Ho-TiO2 NPs respectively. High percent degradation of dye was found at low concentration (20 ppm) and at optimal dosage (0.035 g) of both the catalysts. The rate of Safranin O dye degradation was found to increase with increase in temperature and pH of the medium. DNA binding study revealed that Ho-TiO2 NPs are more capable of binding to human DNA. Antibacterial activity study showed that Ho-TiO2 NPs were more efficient against both gram-negative and gram-positive bacterial strains as compared to pure TiO2. Hemolysis assay showed that TiO2 and Ho-TiO2 nanoparticles are non-biocompatible.Ho-TiO2 nanoparticles showed higher anti-oxidant activity as compared to bare TiO2.

Investigation of Environmental and Therapeutic Applications of Holmium doped Titanium dioxide (Ho-TiO2) nanocatalysts. Kinetic and Thermodynamic study of the Photocatalytic degradation of Safranin O dye

Titanium dioxide (TiO2) and Holmium doped Titanium dioxide(Ho-TiO2) nanoparticles (NPs) were synthesized through Sol Gel method. The synthesized NPs were characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), Energy dispersive X-ray analysis (EDX), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Photoluminescence spectroscopy. DNA binding, antibacterial, hemolytic and antioxidant assays of the synthesized nanoparticles were also carried out for finding their therapeutic applications. Successful doping of TiO2 with Ho reduced the band gap from 3.10 to 2.88 eV. SEM and XRD analysis showed that both TiO2 and Ho-TiO2 NPs exhibit tetragonal structure and as a result of doping the morphology of the particles improved and agglomeration reduced. PL emission intensity of TiO2 also reduced with doping.The holmium doped TiO2 were used for the first time against the degradation of safranin O dye, DNA binding study and biocompatibility assay.The degradation of Safranin Odye over both the catalysts followed first order kinetics. The calculated activation energies for the photo degradation of given dye were found to be 51.7 and 35.2kJ/mol using TiO2 and Ho-TiO2 NPs respectively. At 180 minutes time interval 84% and 87 % dye degradation was observed using pure TiO2 and Ho-TiO2 NPs respectively. High percent degradation of dye was found at low concentration (20ppm) and at optimal dosage (0.035g) of both the catalysts. The rate of Safranin O dye degradation was found to increase with increase in temperature and pH of the medium. DNA binding study revealed that Ho-TiO2 NPs are more capable of binding to human DNA. Antibacterial activity study showed that Ho-TiO2 NPs were more efficient against both gram-negative and gram-positive bacterial strains as compared to pure TiO2. Hemolysis assay showed that TiO2 and Ho-TiO2 nanoparticles are non-biocompatible.Ho-TiO2 nanoparticles showed higher anti-oxidant activity as compared to bare TiO2.

Photocatalytic Activity of Nanocoatings Based on Mixed Oxide V-TiO2 Nanoparticles with Controlled Composition and Size

V-TiO2 photocatalyst with 0 ≤ V ≤ 20 mol% was prepared via the sol–gel method based on mixed oxide titanium–vanadium nanoparticles with size and composition control. The mixed oxide vanadium–titanium oxo-alkoxy nanonoparticles were generated in a chemical micromixing reactor, coated on glass beads via liquid colloid deposition method and underwent to an appropriate thermal treatment forming crystallized nanocoatings. X-ray diffraction, Raman, thermogravimetric and differential thermal analyses confirmed anatase crystalline structure at vanadium content ≤ 10 mol%, with the cell parameters identical to those of pure TiO2. At a higher vanadium content of ~20 mol%, the material segregation began and orthorhombic phase of V2O5 appeared. The crystallization onset temperature of V-TiO2 smoothly changed with an increase in vanadium content. The best photocatalytic performance towards methylene blue decomposition in aqueous solutions under UVA and visible light illuminations was observed in V-TiO2 nanocoatings with, respectively, 2 mol% and 10 mol% vanadium.

Thermo-Optical Characterization of Cu- and Zr-Modified TiO2 Photocatalysts by Beam Deflection Spectrometry

Cu/Zr-modified TiO2 photocatalysts were prepared in the form of nanopowders and characterized by photothermal spectrometry, UV–Vis spectrophotometry and x-ray diffraction (XRD) to investigate the effect of Cu/Zr content on their thermo-optical and transport properties. Adding Cu (0.05%) caused a change in the light absorption range limit, which reduced from 3.25 eV for pure TiO2 to 2.85 eV for Cu-modified TiO2. The decrease in energy band gap was accompanied by a 19.5% decrease in the charge carrier lifetime, which is not favorable for photocatalysis. The decrease in charge carrier lifetime can be minimized by additional modification of TiO2 with Zr (1%), which showed insignificant effects on the energy band gap of the investigated materials. Furthermore, modification of TiO2 with Zr affected the material’s structure and increased its specific surface area, which improved the adsorption of degraded compounds as well as the absorption of light. Altogether, these effects resulted in higher photocatalytic degradation rate constants of the investigated TiO2-based photocatalyst. It was also found that modification of TiO2 with Cu and/or Zr increases both the material’s thermal diffusivity and conductivity due to changes in the band gap and structure of material. Beam deflection spectrometry (BDS) has demonstrated high potential in materials’ characterization which stems from its high sensitivity and precision.

Synthesis and Characterization of Sn/Ni Single Doped and Co–Doped Anatase/Rutile Mixed–Crystal Nanomaterials and Their Photocatalytic Performance under UV–Visible Light

Pure and Sn/Ni co–doped TiO2 nanomaterials with anatase/rutile mixed crystal were prepared and characterized. The results show that pure TiO2 is a mixed crystal structure composed of a large amount of anatase and a small amount of rutile. Sn doping promotes the phase transformation from anatase to rutile, while Ni doping inhibits the transformation. Both single doping and co–doping are beneficial to the inhibition of photoinduced charge recombination. Sn doping shows the best inhibitory effect on photogenerated charge recombination, and increases the utilization of visible light, displaying the highest photocatalytic activity. The decolorization degree of methylene blue (MB) by Sn–TiO2 is 79.5% after 150 min. The reaction rate constant of Sn–TiO2 is 0.01022 min−1, which is 5.6 times higher than pure TiO2 (0.00181 min–1).

Enriched Catalytic Activity of TiO2 Nanoparticles Supported by Activated Carbon for Noxious Pollutant Elimination

Cleaning wastewater has become one of the most serious issues for a number of scientists and researchers in recent years, as water is the most basic need for the daily life of humans. There has been a focus on the removal of noxious pollutants from wastewater effluents by using nanocatalysts owing to their unique physicochemical actions and stability. Herein we manufactured TiO2 nanoparticles supported by activated carbon (AC-TiO2) using a cost-effective sonochemical method. The band structures of the AC-TiO2 and TiO2 were modified from 3.2 to 3.1 eV, thus increasing the catalytic activity. The structural, optical and anatase crystal phase properties, with morphological confirmation, were studied by applying UV-DRS, PL, FESEM, XRD, along with HRTEM, respectively. The specific surface area, calculated by BET analysis, was found to be ~241 m2/gm and ~46 m2/gm for AC-TiO2 and TiO2. The degradation efficiency of the as-prepared nanocatalysts against the very toxic but rarely studied organic textile dye pollutant RO 84 was investigated and 97% efficiency were found for the AC-TiO2 as compared to pure TiO2, which is a highly appreciated finding in the catalytic dye degradation application domain. Such surface-modified nanocatalysts could be further implemented for the treatment of wastewaters/waste effluents released from chemical industries, laboratories and other sources.

Innovative Ag–TiO2 Nanofibers with Excellent Photocatalytic and Antibacterial Actions

Ag–TiO2 nanostructures were prepared by electrospinning, followed by calcination at 400 °C, and their photocatalytic and antibacterial actions were studied. Morphological characterization revealed the presence of one-dimensional uniform Ag–TiO2 nanostructured nanofibers, with a diameter from 65 to 100 nm, depending on the Ag loading, composed of small crystals interconnected with each other. Structural characterization indicated that Ag was successfully integrated as small nanocrystals without affecting much of the TiO2 crystal lattice. Moreover, the presence of nano Ag was found to contribute to reducing the band gap energy, which enables the activation by the absorption of visible light, while, at the same time, it delays the electron–hole recombination. Tests of their photocatalytic activity in methylene blue, amaranth, Congo red and orange II degradation revealed an increase by more than 20% in color removal efficiency at an almost double rate for the case of 0.1% Ag–TiO2 nanofibers with respect to pure TiO2. Moreover, the minimum inhibitory concentration was found as low as 2.5 mg/mL for E. coli and 5 mg/mL against S. aureus for the 5% Ag–TiO2 nanofibers. In general, the Ag–TiO2 nanostructured nanofibers were found to exhibit excellent structure and physical properties and to be suitable for efficient photocatalytic and antibacterial uses. Therefore, these can be suitable for further integration in various important applications.