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Introduction. Detonation spraying is an effective method for applying high-quality coatings to various materials, widely used in industry to improve wear resistance and corrosion resistance of surfaces. This article examines the influence of key process parameters, such as gun-to-substrate distance and nozzle velocity, on the structure and properties of the resulting coatings. Materials and methods of research. The Ti–TiO2 coatings on hot-rolled carbon steel are studied. The spray distance and the speed of nozzle passage are varied while the rest spraying parameters are fixed. The obtained coatings were studied using scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. Results and discussion. It is found that the phase composition of the coating changes depending on the detonation spray conditions. The fraction of rutile exceeds the fraction of anatase in the obtained samples except for the samples obtained with the fastest nozzle passage. The rutile fraction monotonically decreases with an increase in the spray distance with fixed values of the rest parameters of spraying process. It is found a nonmonotonic changing the rutile fraction with an increase in the speed of nozzle passage and found its optimal values. Two new theoretical models for the spray process based on differential equations are proposed, the solutions of which sufficiently describe the dependencies of the rutile fraction on the distance and speed of the nozzle, respectively. Conclusion. It has been demonstrated that the theoretical values of the parameters, calculated using the formulated equations, are in good agreement with the experimentally measured values

Abstract Titanium dioxide nanoparticles, renowned for their abundance, non-toxicity, and stability, have emerged as indispensable components in various fields such as air purification, healthcare, and industrial processes. Their applications as photocatalysts and antibacterial agents are particularly prominent. The synthesis methods significantly influence the properties and subsequent applications of these nanoparticles. While several techniques exist, the biological approach using plant extracts offers advantages such as simplicity, biocompatibility, and cost-effectiveness. This study focused on the green synthesis of titanium dioxide nanoparticles utilizing spinach leaf extract. Within the scope of this investigation, the green synthesis of titanium dioxide nanoparticles through spinach leaf extract were synthesized and optimized, followed by a comprehensive examination of their morphological, structural, and chemical attributes with UV-visible spectroscopy, FTIR spectroscopy, XRD, FESEM, and EDX. The minimum inhibitory concentration (MIC) against E. coli and S. aureus was determined to evaluate their antibacterial potential. Optimal synthesis conditions were identified at 50 °C, using a 1/30 concentration and 20 ml of spinach leaf extract. Spherical anatase nanoparticles, ranging from 10 to 40 nm, were produced under these conditions. The change in the color of the extract, absorption at 247 nm, change and increase of the peak at 800 − 400 wavelengths, and the maximum intensity of X-ray diffraction at the angle of 25.367 with the crystal plane 101 were indications of the synthesis of these nanoparticles. Notably, the synthesized nanoparticles exhibited antibacterial activity with MIC values of 0.5 mg/ml against E. coli and 2 mg/ml against S. aureus. This research presents a novel, eco-friendly approach to synthesizing titanium dioxide nanoparticles with promising antibacterial properties.

High crystalline preferred oriented low strain anatase utilizing a novel and unique approach employing the powder X-ray diffraction (XRD) technique is the prime focus of the investigation. This process effectively enhanced controlled crystalline phase growth with 86.70 % anatase and 13.30 % rutile confirmed through Rietveld refinement in the WPPF method. The prominent crystalline phase providing insights into lattice parameters a = b = 3.7882 Å, c = 9.5143 Å, α=β=γ= 90.0° where lattice strain 0.280 %, lattice volume 136.533 Å3, specific surface area 84.69 m2/g, dislocation density 2.94 × 10–3 nm−2, morphology index 0.722, preference growth -0.087 and packing efficiency 70.13 %. The most intense diffraction was attributed to the (101) plane at 2θ= 25.288° The average crystallite size through various models was 18.45 nm (Scherrer equation), 34.08 nm (Williamson-Hall plot), 22.12 nm (Monshi-Scherrer model), 18.49 nm (Sahadat-Scherrer model), 22.44 nm (Size-strain plot model) and 17.87 nm (Halder-Wagner model) confirming the formation of nano-sized anatase phase of titanium dioxide nanoparticles. The standard powder nanocrystals exhibit a crystallinity of 67.87 %, underscoring the efficacy of the highly oriented anatase with desirable structural and diffraction properties. `This reduction in crystal structure defects and strain, alongside a smaller lattice volume improved stability and high crystalline anatase predominant (101) was observed at low temperatures.

ASCOT (an acronym derived from Ag-Silver, Copper Oxide, Titanium Oxide) is a user-friendly web tool for digital construction of electrically neutral, energy-minimized spherical nanoparticles (NPs) of Ag, CuO, and TiO2 (both Anatase and Rutile forms) in vacuum, integrated into the Enalos Cloud Platform (https://www.enaloscloud.novamechanics.com/sabydoma/ascot/). ASCOT calculates critical atomistic descriptors such as average potential energy per atom, average coordination number, common neighbour parameter (used for structural classification in simulations of crystalline phases), and hexatic order parameter (which measures how closely the local environment around a particle resembles perfect hexatic symmetry) for both core (over 4 Å from the surface) and shell (within 4 Å of the surface) regions of the NPs. These atomistic descriptors assist in predicting the most stable NP size based on lowest per atom energy and serve as inputs for developing machine learning models to predict the toxicity of these nanomaterials. ASCOT's automated backend requires minimal user input in order to construct the digital NPs: inputs needed are the material type (Ag, CuO, TiO2-Anatase, TiO2-Rutile), target diameter, a Force-Field from a pre-validated list, and the energy minimization parameters, with the tool providing a set of default values for novice users.

Background and Objectives: Nanostructured dispersed semiconductor structures are of some interest as functional materials for modern chemoresistive sensing and photocatalytic chemistry. Among the promising semiconductor materials for such applications is, in particular, titanium dioxide in the modification of anatase. Despite a significant number of experimental and theoretical works devoted to the consideration of electrophysical properties of anatase nanophase and various structures based on it, the features of degradation of electrical conductivity of such systems with time are not fully investigated. The aim of this work was to analyze the behavior of the fluctuation component of the voltage drop on partially conducting systems of interelectrode bridges made of anatase nanoparticles under conditions of direct current flow in the quasi-stationary regime (with a slow increase in the voltage drop) and as it approaches the threshold of flow, characterized by a rapid increase in the voltage drop. Materials and Methods: Experimental studies of the charge transfer fluctuations in disperse structures near the percolation threshold were carried out using specially prepared samples consisting of densely packed titanium oxide nanoparticles (TiO2). The technique is based on the registration of time dependences of the voltage drop across the structures when a constant current flows through the system of anatase bridges. The behavior of fluctuation components during the measurement cycles was analyzed using moving estimates of the Hurst exponent of sample structural functions of intensity fluctuations. In addition to the sample values of the Hurst exponent, the sample normalized autocorrelation functions of the fluctuation component were calculated. To interpret the observed features, we propose a qualitative phenomenologicalmodel that considers the influence of random sequences of acts of blocking and soft breakdown of local conduction channels in the studied structures on the degradation of the effective ohmic conductivity of the structures. Results: It has been established that when approaching the threshold of percolation due to the depletion of the ensemble of free charge carriers (electrons) in bridges, there are qualitative changes in the dynamics of voltage drop fluctuations on bridge systems (in particular, a significant increase in the Hurst exponent of structural functions of voltage drop fluctuations, correlating with a sharp decline in the effective ohmic conductivity of the structures under study). “Soft” breakdowns of previously blocked local conduction channels may be due to the Poole – Frenkel effect, leading to the escape of trapped electrons into the conduction zone due to thermal fluctuations when the depth of traps decreases under the influence of an external electric field. Conclusion: The results obtained are of some interest from the point of view of further development of fundamental ideas about charge transfer mechanisms in dispersed semiconductor materials used in chemoresistive sensing and catalytic chemistry.

Water pollution has emerged as a significant worldwide issue, with organic pollutants being a key contributor. Titanium dioxide (TiO2) has demonstrated promising photocatalytic performance in removing organic pollutants under ultraviolet (UV) irradiation. However, the wide band gap (3.2 eV) of TiO2 results in low absorption capacity of visible light, hindering its overall efficiency in degrading organic pollutants. To address the limitation, this research aimed to synthesize visible light-driven TiO2 photocatalyst with different polymorphs (anatase and rutile) and investigate the effect of various doping combination (Nb, B and Nb,B) and concentrations (0.25, 0.50, 0.75 and 1.00 mol%) on the photodegradation efficiency towards methylene blue (MB) dye solution. Anatase phase was obtained when TiO2-based nanopowders were calcined at 400 °C, while the rutile phase was formed at 900 °C based on XRD analyses. Additionally, the morphology analyses revealed that the particle size of anatase is much smaller than that of rutile. The presence of dopants further reduced the particle size of both anatase and rutile phases. Based on UV-Vis absorbance spectra analyses, the anatase Nb,B-TiO2 with 0.50 mol% of dopant concentration exhibited the best photocatalytic performance towards MB. Moreover, the anatse phase of 0.50 mol% Nb,B-TiO2 showed the narrowest band gap of 2.74 eV compared to the TiO2 (3.4 eV), representing a reduction of 19.41 %, according to UV-Vis analyses. These outcomes suggest the potential application of anatase phase of 0.50 mol% Nb,B-TiO2 in treating organic pollutants in wastewater under visible light conditions in future. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

The primary goal of this research outline is the conversion of titanium isopropoxide (TTIP) at 50.0 °C to form a high crystalline preferred oriented predominant (101) with a low crystal strain of 90.0 % anatase-TiO2 phase. With the interval of time, the peptizing agent (IP) reacts to an acidic aqueous medium and preferential growth of anatase-TiO2 has been identified. Exhaustive recombination in X-ray diffraction (XRD) analysis ensures the crystal strain, lattice volume, lattice parameters, d-spacing and crystallite size. UV–vis-NIR showed maximum absorption of 320.0 nm with 0.78 a.u. at blue shift for decreasing nano-size and smaller bandgap 3.0313 eV of larger dimensions anatase-TiO2. The preferred orientation also revealed by nanobeam diffraction (NBD) of TEM enables qualitative lattice type and highly crystal orientated predominant (101) plane 5.60 nm−1 in a diffraction pattern imposed on 200.0 kv parallel electron bean from LaB6 filament.

Photocatalytically active ceramic flat sheet membranes based on a nanostructured titanium dioxide (TiO2) coating were produced for photocatalytic water treatment. The nano-TiO2 layer was produced by a novel combination of magnetron sputtering of a thin titanium layer on silicon carbide (SiC) membranes, followed by electrochemical oxidation (anodization) and subsequent heat treatment (HT). Characterization by Raman spectra and field emission scanning electron microscopy proved the presence of a nanostructured anatase layer on the membranes. The influence of the titanium layer thickness on the TiO2 formation process and the photocatalytic properties were investigated using anodization curves, by using cyclovoltammetry measurements, and by quantifying the generated hydroxyl radicals (OH•) under UV-A irradiation in water. Promising photocatalytic activity and permeability of the nano-TiO2-coated membranes could be demonstrated. A titanium layer of at least 2 μm was necessary for significant photocatalytic effects. The membrane sample with a 10 μm Ti/TiO2 layer had the highest photocatalytic activity showing a formation rate of 1.26 × 10−6 mmol OH• s−1. Furthermore, the membranes were tested several times, and a decrease in radical formation was observed. Assuming that these can be attributed to adsorption processes of the reactants, initial experiments were carried out to reactivate the photocatalyzer. HIGHLIGHTS TiO2-coated membranes for photocatalytic wastewater treatment are promising to overcome the drawbacks of photocatalysis.; A novel coating method for ceramic flat sheet membranes with nanostructured TiO2 is described.; Nano-TiO2 coating is adhesive, permeable, has a high reaction surface, and shows favorable photocatalytic activity.; A decreasing photocatalytic effect with repeated membrane use is discussed.;

Introduction. The use of building materials with photocatalytically active additives is considered as a promising solution to environmental and economic problems of the urban environment. In the field of building materials science the necessity of studying the microstructure of self-cleaning building materials and the influence of impurities on the efficiency of self-cleaning of materials with photocatalytically active additives is determined.Materials and methods. Red gypsum (production waste with photocatalytically active impurities), cement, building gypsum, microsilica, synthesized photocatalytically active titanium oxide – silicon oxide additive, and iron-based pigments were used. Tablet specimens of gypsum-cement-pozzolanic binder with various photocatalytically active components were made: photocatalyst additive, pigments, photocatalytically active oxide impurities. The microstructure of the specimens and the distribution of titanium and iron elements were studied using scanning electron microscopy. The efficiency of self-cleaning was determined by the change in the contact angle of a water drop on a surface coated with oleic acid.Results. The efficiency of self-cleaning of specimens with added and impurity photocatalytically active components was determined. The influence of added impurities on the structure of the material and the influence of the type and concentration of impurities on the efficiency of self-cleaning were revealed.Conclusions. Titanium oxide photocatalyst additive at a concentration of 4.4 % provides high self-cleaning efficiency, evenly distributed throughout the material without affecting the structure of the forming binder stone. Pigment (iron (III) oxide) provides sufficient self-cleaning efficiency at a concentration of 2–9 %, at concentrations of more than 2 % it is distributed unevenly, providing a small increase in self-cleaning efficiency indicators. With the joint introduction of titanium and iron oxides, deterioration in self-purification is observed due to the high degree of recombination of electron – hole pairs. Red gypsum with impurity oxides of titanium and iron has shown a high efficiency of self-cleaning, has a uniform distribution of impurities that do not have a clear effect on the structure of the material.

Polymorphous nanotitania samples were prepared from titanium butoxide (TTB) as a precursor using sol-gel processing in ethanol as a solvent, without and with monoethanolamine (MEA). The experiments used 5.25 mL TTB and MEA with varied volumes of 0.5, 1.0, 1.5, and 2.0 mL. The sample without MEA was specified as sample A, and the samples produced using MEA were specified as samples B, C, D, and E, respectively. All samples were calcined at 500 °C for 4 h and then collected data by X-ray Diffraction (XRD), the Brunauer-Emmett-Teller (BET) method used to analyze Surface Area Analyzer (SAA), Transmission Electron Microscopy (TEM), Raman Spectroscopy, and UV-Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS). The results of XRD characterization indicate that samples A and B form anatase phase, while samples C and D are composed of anatase, brookite, and rutile phases, and sample E is consisted of anatase and brookite phases with weight percentages of (94.53 ± 1.72) % and (5.47 ± 0.36) %, respectively. The presence of the three phases of titania is also confirmed by Raman spectroscopy analysis, which showed anatase peaks at 146, 197, 398, and 513 cm-1, brookite peaks at 245 and 402 cm-1, and rutile peaks at 319, 436, and 612 cm-1. According to XRD, the samples have the particle size in the range of 14-19 nm. A representative sample (sample C) was also characterized using TEM, revealing a particle size of 16.0 ± 0.3 nm. This representative sample revealed the largest surface area of 172.2 m2/g, as seen by BET, and the lowest energy gap of 3.03 eV.

The two largest deposits of Russia – Yaregskoye and Pizhemskoye belong to the same genetic type; hydrothermal-metamorphic indigenous deposits. They are located in the same Timan structure at a distance of no more than 230 km from each other. According to the total approved reserves and forecast resources of titanium dioxide, they are approaching 60% of the all-Russian and will form the basis of industrial titanium raw materials used in Russia in the near future. In the interests of technological mineralogy, morphological features, internal structure, chemical composition of grains of the two main titanium mineral phases ‒ leucoxene and pseudorutile, TiO2 polymorphs, as well as the composition of mineral microinclusions in these phases have been studied in detail. The compositions of all mineral phases in polished preparations of leucoxene and pseudorutile were analyzed by SEM-EDS method at the Institute of Geology and Geochronology of the Precambrian of the RAS, 147 chemical analyses were obtained at the point (3 µk) and many images of polished grains of anatase, leucoxene and pseudorutile were scanned over the area (20×20 µk). In the leucoxene grains themselves, 12 mineral phases were diagnosed and characterized in the form of inclusions: pseudorutile, rutile, anatase, quartz, hydromuscovite-illite, kaolinite, siderite, zircon, xenotime, pyrite, florencite, monazite and kularite. TiO2 polymorphs are verified by Raman spectroscopy and X-ray diffraction analysis. New evidence has been obtained that the transformation of ilmenite into leucoxene occurs hydrothermally through intermediate phases ‒ Fe-rutile and pseudorutile; the enlargement of rutile crystals in the leucoxene grain itself is shown; the presence of secondary crystals of siderite, florencite and others inside the studied grains.

This study investigates the synthesis of TiO2 using the rind of Aloe vera (L.) Burm extract as a green-capping agent. It was discovered that adding the studied extract up to 10 % (TOAv10) increased the surface area and pore volume while maintaining the spherical shape of the nanoparticles. Overall, the TOAv4 sample has the highest photocatalytic activity compared to other samples and a good photocatalytic activity compared to TiO2 prepared without extract. The current findings provide an environmentally friendly and low-cost protocol for the synthesis of TiO2 nanoparticles in the application of wastewater treatment.

The processing of anatase ores by sulphuric acid digestion is well known for its low titanium dissolution yields, which makes the process economically and technically unfeasible. Anatase is considered much less reactive than other forms of titanium such as ilmenite and rutile. Generally, to enhance its dissolution, thermal processes along with acid and/or alkaline leaching processes are necessary. Studies of direct sulphuric acid digestion are few and the reported yields of titanium dissolution are 2 and 15% iron oxide—the main impurity. It also contained silica, aluminum, phosphorus, calcium, and rare earth elements (REE) in concentrations that varied from 1.61% to 6.01%.

Early biofilm formation could be inhibited by applying a thin biocompatible copper coating to reduce periprosthetic infections. In this study, we deposited crystalline Cu-doped TiO2 films using one-step DC magnetron sputtering in an oxygen atmosphere on a biased Ti6Al4V alloy without external heating. The bias voltage varied from −25 V to −100 V, and the resultant substrate temperature was measured. The deposited coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness, scratch and hydrophilicity tests, potentiodynamic polarization measurements, and antibacterial assays against S. aureus and E. coli. The findings demonstrated that when a higher negative bias is applied, the substrate temperature drops, and the anatase to rutile transformation is initiated without indicating obvious Cu-containing phases. The SEM images of the films showed spherical agglomerates with homogeneously distributed Cu with decreasing Cu content as the bias value increased. Higher bias results in the grain refinement of the thinning coatings with more lattice microstrain and more defects, together with an increase in water contact angles and hardness values. Samples biased at −75 V exhibited the highest adhesive strength between coatings and substrate, whereas the specimen biased at −50 V demonstrated higher corrosion resistance. Cu-containing TiO2 coatings with pure anatase phase composition and Cu concentrations of 2.62 wt.% demonstrated excellent bactericidal activity against both S. aureus and E. coli. The layers containing 2.34 wt.% Cu exhibited very good antibacterial properties against S. aureus, only. According to these findings, the produced copper-doped TiO2 coatings have high bactericidal qualities in vitro and may be used to prepare orthopaedic and dental implants in the future.

The use of multiple wavelengths to excite Titanium Dioxide Raman scattering in the near-infrared was investigated for optical nanothermometry. Indeed, Raman spectroscopy can be a very interesting technique for this purpose, as it offers non-disruptive contactless measurements with a high spatial resolution, down to a few µm. A method based on the ratio between the anti-Stokes and Stokes peaks of Anatase Titanium Dioxide was proposed and tested at three different wavelengths, 785, 800 and 980 nm, falling into the first biological transparency window (BTW-I). Using a temperature-controller stage, the temperature response of the sample was measured between 20 and 50 °C, allowing the thermal sensitivity for this range to be estimated. The use of sufficiently high laser power results in the generation of local heating. A proof of concept of the proposed thermometric method was performed by determining the extent of local heating induced by increasing laser power. By exciting with an 800 nm laser at low power intensities, a temperature equal to room temperature (RT) was found, while a maximum temperature increase of 15 °C was detected using the anti-Stokes/Stokes method.

We investigated the polaron-assisted nonadiabatic dynamics in protonated TiO2, as well as the polaron-H2O coupling and its effects on the relaxation of photogenerated electrons. We observed that different polaron hopping regimes result in varied nonadiabatic couplings and relaxations of excited electrons from the conduction band minimum to the gap states of protonated TiO2, with a weak dependence on the actual trapping site of the polaron. Surface-adsorbed H2O molecules can attract polarons toward the adsorbed Ti sites, with the coupling between H2O and the polaron being inversely proportional to their distance. Our findings suggest that the lifetime of the photogenerated charge carriers can be extended by reducing the polaron-H2O distances, with expected benefits to the efficiency of the reduced TiO2 samples for photocatalytic applications.

Titanium slag is a by-product of iron extraction from Ilmenite ore. Titanium slag has a high TiO₂ content, so it is a suitable material for preparing TiO₂. This study investigated the influence of the slag particle size on the ability to synthesise TiO₂ by the hydrothermal alkalisation method. Three groups of titanium slag powder with average particle sizes from 18 μm to 108 μm were alkalised with a 10M NaOH solution to separate TiO₂ by the hydrothermal method. The mixing ratio by mass between the slag and the 10M NaOH solution is 1:1.5. The hydrothermal reaction was carried out at 180 °C for 7 hours. The products were analysed for their mineral, chemical, and microstructural properties using X-ray diffraction, X-ray fluorescence, scanning electron microscopy with energy-dispersive detector. The results show that the particle size significantly influences the efficiency of the TiO₂ chemical extraction from the titanium slag. The formed TiO₂ is of high purity, and the main mineral composition is anatase. The anatase polymorph of TiO₂ has the potential application as a photocatalyst and an antibacterial material.

Abstract This study aimed to prepare antifouling and highly mechanical strengthening membranes for brackish and underground water desalination. It was designed from cellulose acetate (CA) loaded anatase. Anatase was prepared from tetra-iso-propylorthotitanate and carboxymethyl cellulose. Different concentrations of anatase (0.2, 0.3, 0.5, 0.6, 0.7, and 0.8)% were loaded onto CA during the inversion phase preparation of the membranes. The prepared membranes were characterized using Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM & EDX), mechanical properties, swelling ratio, porosity determination, and ion release. The analysis confirmed the formation of anatase on the surface and inside the macro-voids of the membrane. Furthermore, anatase loading improved the CA membrane’s mechanical properties and decreased its swelling and porosity rate. Also, CA-loaded anatase membranes displayed a significant antibacterial potential against Gram-positive and Gram-negative bacteria. The results showed that the salt rejection of the CA/anatase films as-prepared varies considerably with the addition of nanomaterial, rising from 46%:92% with the prepared membranes under the 10-bar operation condition and 5 g/L NaCl input concentration. It can be concluded that the prepared CA-loaded anatase membranes have high mechanical properties that are safe, economical, available, and can stop membrane biofouling.

This research aims to evaluate the efficacy of Mouromtseff’s numbers in assessing the thermal transfer performance of titanium oxide (TiO2) nanosized dispersions in convective heat transfer through a pipe. New experimental coefficients of convective heat transfer, thermophysical and rheological characterisation are carried out for TiO2-based nanodispersions in an aqueous propylene glycol 30 vol% mixture at various nanoadditive mass loadings (from 0.25 to 2.0 wt%). Different Mouromtseff’s number formulations, including the Dittus–Boelter and Simons expressions, were obtained from experimental data of thermophysical properties, enabling concise analyses on the prospective improvement of heat transfer in cooling and heating systems. The morphology, particle size, and crystallinity of the anatase TiO2 nanopowder were confirmed, and the stability of the nanofluids with various surfactants was evaluated, with PSS at a 1:4 mass ratio being optimal. Slight increments in thermal conductivity (up to 1.5%) and density (up to 1.3%) with nanoparticle loading were observed, while isobaric heat capacity presents a decreasing trend (less than 13%). Dynamic viscosity increases with higher nanoadditive concentrations, 8.8% for the 2.0 wt% A-TiO2/PG:W 30:70 + PSS 1:4 nanofluid. The employed Dittus–Boelter and Simons expressions correctly predict a worsening of the convective heat transfer, but the percentages diverge slightly from experimental data.

Titania nanoparticles (NPs) find wide application in photocatalysis, photovoltaics, gas sensing, lithium batteries, etc. One of the most important synthetic challenges is maintaining control over the polymorph composition of the prepared nanomaterial. In the present work, TiO2 NPs corresponding to anatase, rutile, or an anatase/rutile/brookite mixture were obtained at 80 °C by an inverse microemulsion method in a ternary system of water/cetyltrimethylammonium bromide/1-hexanol in a weight ratio of 17:28:55. The only synthesis variables were the preparation of the aqueous component and the nature of the Ti precursor (Ti(IV) ethoxide, isopropoxide, butoxide, or chloride). The materials were characterized with X-ray diffraction, scanning/transmission electron microscopy, N2 adsorption–desorption isotherms, FTIR and Raman vibrational spectroscopies, and diffuse reflectance spectroscopy. The synthesis products differed significantly not only in phase composition, but also in crystallinity, textural properties, and adsorption properties towards water. All TiO2 NPs were active in the photocatalytic decomposition of rhodamine B, a model dye pollutant of wastewater streams. The mixed-phase anatase/rutile/brookite nanopowders obtained from alkoxy precursors showed the best photocatalytic performance, comparable to or better than the P25 reference. The exceptionally high photoactivity was attributed to the advantageous electronic effects known to accompany multiphase titania composition, namely high specific surface area and strong surface hydration. Among the single-phase materials, anatase samples showed better photoactivity than rutile ones, and this effect was associated, primarily, with the much higher specific surface area of anatase photocatalysts.

Thin films of pristine titanium dioxide (TiO2) and doped with different concentrations (0–8) at.% of nickel (Ni) were synthesized onto transparent glass substrates using the spray pyrolysis deposition technique. Field emission scanning electron microscopy revealed the porous and agglomerated surface morphology of the films. X-ray diffractometer demonstrated the anatase crystal structure with a nominal increment of (101) peak. The shifting of peak position revealed the expansion of the unit cell volume from 134.64 to 137.54 (Å)3 whereas crystallite size increased from 34 to 63 nm. Using the Fizeau fringes technique, the thickness of the films was determined between 165 and 190 nm. UV–Vis measurements were employed to examine the optical characteristics of the films. The red shift was observed for 2 at.% Ni content (3.38 eV) while the blue shift was observed for (4–8) at.% Ni content. The wavelength-dependent refractive index and dielectric constant showed anomalous dispersion in the absorption band, representing the transparency of the films. The 4-point probe measurement showed a decreasing trend of resistivity with increasing temperature, whereas the resistivity increased with Ni content. Activation energy indicated a higher amount of adsorbed oxygen in the films due to the high amount of Ni content.

TiO2 is one of the most important metal oxides which are widely applied in various fields, and the modifications of synthesis process and in-depth characterization are growing up day by day. Nano Anatase and Rutile phases of TiO2 were synthesized from titanium iso-butoxide following an easy approach where no toxic chemicals were utilized. Nano-TiO2 (Rutile phase) was synthesized from the thermal conversion of the nano-Anatase phase (which was obtained at room temperature) at 700 °C temperature for 2 h. Anatase and Rutile phases were confirmed by the X-ray diffraction (XRD) data and matched with the standard database. Different crystallographic parameters such as lattice parameters, and preference growth were calculated from the XRD data. Different methods were utilized to estimate the crystallite size of the Anatase and Rutile phase of TiO2 by using the Scherrer equation, Williamson-Hall plot, Monshi-Scherrer Model, Size-strain plot method, Halder- Wagner Model, and Sahadat-Scherrer Model. All the models presented crystallite size in the accepted region, and linear regression coefficients were also taken into consideration. In addition to the crystallite size, various intrinsic parameters such as stress, strain and energy density were also computed from the mentioned models based on XRD.

Recently, TiO2(B) has been extensively used in catalytic and energy fields owing to its exceptional crystal structure. But being a metastable state, TiO2(B) is transformed easily into other stable crystalline forms like anatase or rutile phase, and the low crystallinity limits the application of the material in catalysis. A combination of TiO2(B) with anatase, which is benefitted by a homojunction, is proven to be blessed with high activity. Herein, hydrogen production via photocatalytic water-splitting is presented using Cu modified biphasic titania nanotubes achieved by a facile hydrothermal procedure. The systems are well characterized using SEM, TEM, XRD analysis, N2 adsorption study, FTIR, DR-UV, Raman, Photoluminescence, and X-ray photoelectron spectral analysis. The homo-junction developed in titania due to anatase –TiO2 (B), as well as the heterojunction created by the co-catalyst, tune the photocatalytic activity of TiO2 nanotubes positively, as evident from the enhanced hydrogen production over the system.

TiO2-Al2O3 supports with different incorporation methods of titania were synthesized via three methods: impregnation (TA-I), co-precipitation (TA-CP), and co-precipitation–hydrothermal treatment (TA-HT). And the NiMoP catalysts prepared on the corresponding supports were evaluated for hydrodesulfurization (HDS) reactions. The results demonstrated that the Ti atoms in TA-I are attached to alumina through hydroxyl groups, while the Ti atoms in TA-CP and TA-HT can be dispersed in the alumina skeleton. Variations in the incorporation modes of TiO2 affect the support properties, consequently influencing the nature of the active metal on the supports. The Ti atoms dispersed in the Al2O3 skeleton allow an increase in the basic hydroxyl groups. Meanwhile, TiO2 in TA-CP and TA-HT can absorb hydrogen molecules and be partially reduced. Furthermore, metal species supported on the TA-CP and TA-HT are more easily reduced and better dispersed. For the NiMoP catalysts prepared with TA-CP and TA-HT, the Ti element promotes the sulfidation degree of Mo, besides shortening the average (Ni)MoS2 slab. The catalysts prepared with TA-CP exhibited superior activity for 4,6-DMDBT hydrodesulfurization. This can be ascribed not only to the relatively high sulfidation degree of Mo and proportion of the NiMoS active phase but also to the well-dispersed (Ni)MoS2 slabs. Moreover, the Ti4+ ions dispersed in the Al2O3 skeleton can be partially reduced to act as electron donors, enhancing the metallic character of the S layers in MoS2, which facilitates the improvement of the hydrogenation desulfurization activity.

Abstract The photoelectrochemical properties of titanium dioxide (TiO2) nanoparticles are directly related to the presence of certain facets. The synthesis of such particles is challenged using volatile and sensitive precursors utilizing shape capping agents. In this study, an easier two‐step synthesis technique for the preparation of well‐specified morphology TiO2 nanocrystals from TiO2 powder is demonstrated. The facet‐dependent Fermi level and flat band potential of the prepared particles are calculated and their photoelectrochemical properties are investigated by Cu2+ and Pb2+ photo/electrodeposition. From Cu2+ electrodeposition, it is shown that the presence of {100} and {001} facets in cubic morphology facilitates the electrodeposition with progressive nucleation mechanisms, while the presence of {101} facet in octahedral geometry follows instantaneous nucleation mechanisms. The activity of electroreduction is also related to the flat‐band potential which shows the highest activity in Pb2+ electrodeposition for octahedron nanostructure due to the alignment of the reduction potential to the edge of the flat band. Photodeposition of Cu2+ and Pb2+ ions shows identical trends to electrodeposition indicating the facets influence in ion adsorption and structure of the bandgap of morphological TiO2. The findings emphasize the importance of facet‐dependent surface adsorption and bandgap structure designing faceted TiO2 nanoparticles for tailored applications.

The work reported here compared between two photocatalytic degradation strategies of 2-chlorophenol (2-CP). The first strategy utilized titanium dioxide (TiO2) immobilized on activated carbons (AC) to produce TiO2/AC photocatalysts of various TiO2 loadings. Various immobilization techniques were used: chemical vapour deposition (CVD), direct air hydrolysis (DAH), high-temperature impregnation (HTI). In the first strategy, characterization, adsorption and photocatalytic degradation of 2-CP using TiO2/AC revealed that: 1) deposition of anatase TiO2 occurred in the micro pores of AC; 2) adsorption capacity decreased with increasing anatase TiO2 loading on TiO2/AC; 3) adsorption kinetics followed pseudo first order kinetics where 40 % of 2-CP was adsorbed; 4) photocatalytic degradation caused removal of all 2-CP and 80 % of total organic carbon (TOC), while no chloride ion (Cl−) was produced. In the second strategy, naked TiO2 (anatase) and mixtures of (anatase and AC) were involved to investigate the effect of presence of AC on degradation ability of anatase TiO2 towards 2-CP. The results showed that: 1) naked TiO2 (anatase) caused better degradation of 2-CP than TiO2/AC (Cl− was liberated; complete degradation of 2-CP occurred; some TOC remained in the suspension); 2) presence of AC with anatase TiO2 in the reaction mixture negatively affected Cl− production, but positively affected 2-CP and TOC disappearance; 3) when all 2-CP was adsorbed on AC, production of Cl− was inhibited but continued at a reduced rate. This might indicat that both dissolved and adsorbed 2-CP contributed to the degradation process.

Dyes are produced as water pollutants in the textile, plastic, and dye industries. Many efforts have been made to remove dyes from industrial wastewater. In this area, Photocatalytic performance under Vis-lights is a useful and effective method. In this study, a series of highly efficient Sn-doped TiO2 photocatalysts were successfully developed using a simple heat treatment process. Three concentrations of SnCl2 powder (3%, 5%, and 7 %) were used for the preparation of materials. The characterizations of resulting materials were distinguished by scanning electron microscopy (SEM), diffusion reflection spectroscopy (DRS), and X-ray diffraction spectroscopy (EDX). Also, methyl orange dye was served to indicate the photocatalytic activity of Sn-doped material under visible light irradiation. The results indicated that both doped and also pure TiO2 have a uniform size. Anatase was the only identified phase in all the products, whether doped or un-doped. The resulting Sn-doped materials have demonstrated a band gap value range of 3.14 to 2.68 eV in comparison with pure TiO2 which shows a value of 3.2 eV. The photocatalytic evaluations indicated that the samples prepared in the presence of 3, 5, and 7% SnCl2 have degradation efficiencies of 85%, 85%, and 90%, respectively within 120 min, which are much higher than that of un-doped TiO2. The enhancement in the efficiency was attributed to the gap changes in anatase by the incorporation of Sn ions into the TiO2 lattice structure. Compared to pure TiO2, which has a band gap of 3.2 eV, the band gap values for doped TiO2 ranged from 3.14 to 2.68 eV.

BACKGROUND Rutile, anatase and brookite are TiO2 polymorphs. In the rutile in-situ U-Pb dating, rutile was determined primarily on electron microprobe data and cathodoluminescence images, while these methods sometimes could not effectively distinguish rutile, anatase and brookite. If there are a small number of the TiO2 polymorphs in the sample, the obtained age may be a mixed age with no significant geological significance. Therefore, the identification of TiO2 polymorphs is very important. OBJECTIVES To identify TiO2 polymorphs from the bauxite deposit in central Guangxi. METHODS TiO2 minerals in bauxite from central Guangxi were used as the research object, and laser Raman spectroscopy was applied to the identification of TiO2 isomorphic minerals. RESULTS Four groups of laser Raman spectral lines with different characteristics were identified. The first three groups have laser Raman spectral peaks of anatase, rutile and brookite, respectively. The fourth group has two kinds of laser Raman spectral characteristic lines, one has both anatase characteristic peaks of 144, 198, 397, 513, 636cm-1 and rutile characteristic peaks of 442, 607cm-1, the other has both anatase characteristic peak of 144cm-1 and brookite characteristic peak of 153, 247, 325, 636cm-1. CONCLUSIONS The TiO2 polymorphs of the bauxite deposit includs rutile, anatase, brookite and intermediate minerals that undergo phase transformation. The study indicates that the bauxite deposit in central Guangxi may have undergone a later regional metamorphism, leading to the transformation of TiO2 polymorphs. The laser Raman spectroscopy provides a new method for the identification of TiO2 polymorphs andrutile for in-situ U-Pb dating.

The main objective of this study was to investigate the photodegradation of azo dye Cibacron Brilliant Yellow 3G-P using Anatase, Degussa-P25 and ZnO. These semi-conductors were characterized using XRD, BET and TEM-EDX. The variation of the amount of semi-conductors significantly affect the rate of color removal. The decolorization rate increased as the catalyst dosage was increased. Other parameters were also studied, such as stirring speed, pH, and initial dye concentration. It was found that the rate of decolorization increases with the increase of stirring speed. Decolorization of about 30, 60 and 80% was respectively achieved in the case of Anatase, Degussa-P25 and ZnO at low stirring speed (50rpm). At pH = 3, the degradation rate was found to be higher than the alkaline pH, about 95.58 and 85.71% of color has been decolorized with Anatase and Degussa-P25 respectively. While using ZnO, the color removal reached maximum in acidic and alkaline solutions, more than 95% of dye was decolorized. The concentrations dye solutions less than 80ppm led to the removal rate of about 95% in the case of ZnO, while it was only about 8–15% in the case of TiO2 with the concentration more than 20 ppm. HIGHLIGHTS Decolourization and photocatalytic degradation of Cibacron Brilliant Yellow 3G-P under UV light radiation.; Anatase displayed higher photocatalytic efficiency than Degussa-P25 and ZnO.; The photocatalytic degradation efficiency of Anatase and Degussa-P25 was observed to be higher at pH = 3.;

The phase composition and morphology of boron-containing TiO2 nanoparticles obtained by the sol-gel method were investigated. The solution of titanium aqua complex [Ti (OH2)6]3+‧3Cl- was used as a precursor. Borate acid Н3ВО3 (promoter of the formation of rutile) was used as a modified reagent. A single-phase rutile TiO2 was obtained at a concentration of borate acid in the reaction mixture, which causes the formation of a 0.5В-TiO2 sample. The particles of 0.5В-TiO2 samples were in the villi-form, with a diameter of 0.8-1.2 nm, and a length of 16-24 nm. With an increase of the Н3ВО3 concentration in the reaction mixture, synthesized oxide materials (samples of 1.0В-TiO2 and 1.5В-TiO2) contain 70 % and 57% of anatase respectively, in addition to rutile phase. Titanium-borate monodentate molecules Ti(OH)3OB(OH)2‧2Н2О were formed during the synthesis of the 0.5B-TiO2 rutile sample. The interatomic distance of Ti-O in these particles is commensurate with the average length of the Ti-O – bond of TiO6 rutile octahedra. During the polycondensation process, the distance of the Ti-O molecule-promoter was reproduced as a pattern in the following octahedra of rutile crystals. Two types of titanium-borate molecules are formed in the reaction medium, during the synthesis of 1.0В-TiO2 and 1.5В-TiO2 samples. Molecules with a bidentate mononuclear structure Ті(ОН)2О2ВОН‧2Н2О in which the interatomic distance of Ti-O is commensurate with the average length of the Ti-O –bond in the anatase octahedra was formed. Therefore, titanium-borate molecules of the second type act as a promoter of the formation of the TiO2 anatase phase.

Abstract The TiO2 nanotube arrays were prepared by anodization, and the crystal structure was changed by calcination at different temperatures. The photocatalytic performance of the samples was measured by the degradation of rhodamine B under visible light. The TiO2 nanotubes calcined at 600 °C showed higher photocatalytic activity than other samples. The prepared catalyst is characterized by a variety of techniques, including X-ray diffraction, scanning electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy, Raman, photoluminescence spectroscopy and electrochemical testing. The reasons for improving the catalytic activity were studied from the aspects of crystal structure, surface morphology, and photoelectric properties, and the catalytic mechanism was studied. The results show that the TiO2 nanotubes calcined at 600°C contain two phases of anatase and rutile. Compared with pure phase TiO2, the charge transfer resistance is reduced and the electron-hole reorganization is well suppressed. In addition, it affects the band structure and improves the absorption of visible light. At the same time, studies have found that the main active substances in the catalytic process are h+ and •OH.

Abstract Despite the recent success of CdS/Sb2Se3 heterojunction devices, cadmium toxicity, parasitic absorption from the relatively narrow CdS band gap (2.4 eV) and multiple reports of inter‐diffusion at the interface forming Cd(S,Se) and Sb2(S,Se)3 phases, present significant limitations to this device architecture. Among the options for alternative partner layers in antimony chalcogenide solar cells, the wide band gap, non‐toxic titanium dioxide (TiO2) has demonstrated the most promise. It is generally accepted that the anatase phase of the polymorphic TiO2 is preferred, although there is currently an absence of analysis with regard to phase influence on device performance. This work reports approaches to distinguish between TiO2 phases using both surface and bulk characterization methods. A device fabricated with a radio frequency (RF) magnetron sputtered rutile‐TiO2 window layer (FTO/TiO2/Sb2Se3/P3HT/Au) achieved an efficiency of 6.88% and near‐record short–circuit current density (Jsc) of 32.44 mA cm−2, which is comparable to established solution based TiO2 fabrication methods that produced a highly anatase‐TiO2 partner layer and a 6.91% efficiency device. The sputtered method introduces reproducibility challenges via the enhancement of interfacial charge barriers in multi‐phase TiO2 films with a rutile surface and anatase bulk. This is shown to introduce severe S‐shaped current–voltage (J–V) distortion and a drastic fill–factor (FF) reduction in these devices.

The inclusion of particles in a polymeric substrate to achieve certain properties is a well-known practice. In the case of textile substrates, this practice may deeply affect the structure of the produced yarns, as even a filament with no textile applications can be obtained. In this manuscript, titanium dioxide (TiO2) particles were incorporated into polyester (PET) chips and the influence of these fillers on the properties of yarn and fabric, and the ultraviolet protection factor (UPF) was assessed. For this purpose, rutile and anatase crystalline forms of TiO2, as well as the size of the particles, were evaluated. Moreover, parameters such as mechanical properties, orientation of the macromolecules and thermal behavior were analyzed to ensure that the textile grade is maintained throughout the production process. The results showed that the inclusion of micro- and nanoparticles of TiO2 decreases the molecular weight and tenacity of PET. Also, although orientation and crystallinity varied during the textile process, the resulting heatset fabrics did not present important differences in those parameters. Finally, the attainment of textile-grade PET-TiO2 fabrics with UPF indexes of 50+ with both rutile and anatase and micro- and nano-sized TiO2 forms was demonstrated.

Various surface modification strategies are being developed to endow dental titanium implant surfaces with micro- and nano-structures to improve their biocompatibility, and first of all their osseointegration. These modifications have the potential to address clinical concerns by stimulating different biological processes. This study aims to evaluate the biological responses of ananatase-modified blasted/etched titanium (SLA-anatase) surfaces compared to blasted/acid etched (SLA) and machined titanium surfaces. Using unipolar pulsed direct current (DC) sputtering, a nanocrystalline anatase layer was fabricated. In vitro experiments have shown that SLA-anatase discs can effectively promote osteoblast adhesion and proliferation, which are regarded as important features of a successful dental implant with bone contact. Furthermore, anatase surface modification has been shown to partially enhance osteoblast mineralization in vitro, while not significantly affecting bacterial colonization. Consequently, the recently created anatase coating holds significant potential as a promising candidate for future advancements in dental implant surface modification for improving the initial stages of osseointegration.

This review provides a detailed exploration of titanium dioxide (TiO2) photocatalysts, emphasizing structural phases, heterophase junctions, and their impact on efficiency. Key points include diverse synthesis methods, with a focus on the sol-gel route and variants like low-temperature hydrothermal synthesis (LTHT). The review delves into the influence of acid-base donors on gelation, dissects crucial drying techniques for TiO2 aerogel or xerogel catalysts, and meticulously examines mechanisms underlying photocatalytic activity. It highlights the role of physicochemical properties in charge diffusion, carrier recombination, and the impact of scavengers in photo-oxidation/reduction. Additionally, TiO2 doping techniques and heterostructures and their potential for enhancing efficiency are briefly discussed, all within the context of environmental applications.

Abstract Titanium dioxide (TiO2) has been used in numerous paintings since its creation in the early 1920s. However, due to this relatively recent adoption by the art world, we have limited knowledge about the nature and risk of degradation in museum environments. This study expands on the existing understanding of TiO2 facilitated degradation of linseed oil, by examining the effect of visible light and crystallographic phase (either anatase or rutile) on the reactivity of TiO2. The present approach is based on a combination of experimental chemical characterization with computational calculation through Density Functional Theory (DFT) modeling of the TiO2-oil system. Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FT-IR) enabled the identification of characteristic degradation products during UV and visible light aging of both rutile and anatase based paints in comparison to BaSO4 and linseed oil controls. In addition, cratering and cracking of the paint surface in TiO2 based paints, aged under visible and UV–vis illumination, were observed through Scanning Electron Microscopy (SEM). Finally, Density Functional Theory (DFT) modeling of interactions between anatase TiO2 and oleic acid, a fatty acid component of linseed oil, to form a charge transfer complex explains one possible mechanism for the visible light activity observed in artificial aging. Visible light excitation of this complex sensitizes TiO2 by injecting an electron into the conduction band of TiO2 to generate reactive oxygen species and subsequent degradation of the oil binder by various mechanisms (e.g., formation of an oleic acid cation radical and other oxidation products). Graphical Abstract

Red mud (RM) a solid waste generated by the bauxite smelting industry, is a rich source of metal resources, especially Ti, and its recycling can bring significant environmental and economic benefits. In this study, precious metal Ti was efficiently recovered from red mud using a coupled acid leaching and boiling route for the effective separation of low-value metals. The red mud which contained mainly 10.69% Si, 12.1% Al, 15.2% Ca, 10.99% Fe, and 4.37% Ti, was recovered in five steps. First, a nitric acid solution was used to leach the metals in multiple stages, resulting in an acidic leach solution with high concentrations of Fe, Al, Ti, and Ca ions 2.7 g/L, 4.7 g/L, 5.43 g/L, and 1.8 g/L, respectively. Then, a small amount of sucrose was added as a catalyst to recover Ti from the leach solution under hydrothermal conditions, resulting in the targeted recovery of 98.6% of Ti in the form of high-purity anatase while Fe, Al, and Ca remained in the solution. Next, the Fe in solution was separated as hematite products at a temperature of 110°C and a reaction time of 4 h. Similarly, the Al in the solution was separated and precipitated as boehmite by heating it at 260°C for a reaction time of 20 h. Finally, the remaining Ca in solution was recovered by simple pH regulation. Economic accounting assessment showed that the method yields $101.06 for 1 t of red mud treated, excluding labor costs. This study provides a novel approach to recover precious metals from metal wastes through the whole process resource recovery of solid waste red mud.

The inherent single narrow emission peak and fast anion exchange process of cesium lead halide perovskite CsPbX3 (X = Cl, Br, I) nanocrystals severely limited its application in white light-emitting diodes. Previous studies have shown that composite structures can passivate surface defects of NCs and improve the stability of perovskite materials, but complex post-treatment processes commonly lead to dissolution of NCs. In this study, CsPb(Cl/Br)3 NCs was in-situ grown in TiO2 hollow shells doped with Eu3+ ions by a modified thermal injection method to prepare CsPb(Cl/Br)3/TiO2:Eu3+ composites with direct excitation of white light without additional treatment. Among them, the well-crystalline TiO2 shells acted as both a substrate for the dopant, avoiding the direct doping of Eu3+ into the interior of NCs to affect the crystal structure of the perovskite materials, and also as a protection layer to isolate the contact between PL quenching molecules and NCs, which significantly improves the stability. Further, the WLED prepared using the composites had bright white light emission, luminous efficiency of 87.39 lm/W, and long-time operating stability, which provided new options for the development of perovskite devices.

Stimulated by the extraordinary power conversion efficiency (PCE) of hybrid organic-inorganic perovskites (HOIP) based solar cells (SCs), the derivative studies on inorganic perovskites (IOP) based SCs have been intensely investigated. In order to overcome the disadvantages of CsPbBr3, most prominently the unfavorable larger band gap (2.3eV), a grating layer of mesoporous anatase TiO2(mp-TiO2) has been inserted into the conventional configuration of SCs. The grating layer acts as the electron transfer layer (ETL) and light absorption strengthening layer at the same time. Due to the combined effects, the increased contacting area increased the fill factor (FF) and enhanced light trapping in the grating layer increased the short-current density, the average PCE of IOP based SCs has increased from 5.67% to 7.58%, which is a ca. 34% increase relatively. Furthermore, research on traditional HOIP-based SCs is also conducted. Interestingly, the increasing PCE mechanism is quite different from their inorganic counterparts, which should be attributed to the strain effect of different film structures. Thus, the strain-induced defect charge-state transitions of MAPbI3 by the grating layer increased the open-circuit voltage (Voc); and similarly, the increased contacting area also increased the FF, resulting in a 13% increase for PCE.

Titania is an established photocatalytic material. The dispersion of titania nanoparticles on kaolinite particles as carrier and support precursor, TiO2-kao, has been studied to avoid losses in photocatalytic efficiency once fired by single-fired porcelain tile route. The photocatalyst was prepared using the hydrolytic sol-gel route. A commercial titania, P25, was used as a reference TiO2. The samples were fast fired at 800, 1015, 1100, and 1185 °C. Degradation of methylene blue was used to assess the photocatalytic performance. TiO2-kao and P25 applied to unglazed plates fired at 800 °C yielded ∼65% degradation, ∼50% due to photocatalysis, and ∼15% due to photolysis. P25 samples retained ∼10% of their photoactivity after firing at 1185 °C, TiO2-kao retained 80%. TiO2-kao on glazed tiles fired at 1185 °C retained 30% photoactivity. The photocatalytic losses in the glazed sample were due to the reduction in contact area caused by particle encapsulation in the glass layer.

Abstract In order to investigate the stimulating effect of TiO2 nanoparticles on the growth rate and the increase of some metabolites in the microalgae Spirulina platensis, the anatase and rutile forms of the TiO2 nanoparticle were compared to the bulk form, in the presence or absence of citrate, on the microalga. The highest chlorophyll, carotenoid, phycocyanin (PC), allophycocyanin (APC), and phycoerythrin (PE) were observed on 3rd day. The highest PC and APC/PE were obtained by rutile and anatase, respectively. Rutile NPs could stimulate the increase of dry biomass and maximum specific growth rate (µm) better than anatase and even the bulk form. Carbohydrate production was stimulated by bulk and rutile. Low concentrations of nanoparticles often had a better effect in increasing PC, APC, and PE pigments. The addition of citrate without TiO2 stimulated the production of astheaxanthin, lipid, protein, and ROS. The simultaneous treatment by citrate-TiO2 was able to reduce the negative effect of nanoparticles on dry weight, but totally, its effect was dependent on the form of TiO2 and stress time. Antioxidant activity was stimulated by the bulk form and caused a decrease in Malondialdehyde (MDA), but an increase in MDA was observed by nanoparticles. The highest ROS was observed in the treatment with rutile (with citrate) on the 3rd day. In general, the stimulating effect of TiO2 on the improvement of indices or its negative effects on S.platensis microalga depended on the form and concentration of TiO2, the presence or absence of citrate, and the duration of treatments. IntroductionThe titanium element, in some cases, improves plant metabolic processes (Gohari et al., 2022; Carvajal and Alcaraz 1998). TiO2 nanoparticles in different forms have many applications in industry, and it is possible to find their way into aquatic ecosystems (Yang et al., 2015). The two forms of anatase and rutile have different surfaces, structural, and toxicity properties (Parrino et al., 2021). Some studies have shown that anatase has more cytotoxicity and photocatalytic activity than the rutile form (Clément et al., 2013). Of course, some sources mention TiO2 with low toxicity (Parrino et al., 2021). However, the effects of TiO2 nanoparticles depend on the type of organism under investigation, nanoparticle concentration, physicochemical and morphological characteristics such as its size and crystal structure. S. platensis, a spiral filamentous blue-green microalgae, has attracted the attention of researchers due to its numerous economic applications, including as a fertilizer and enhancer in agriculture, and has valuable minerals, vitamins, and nutritional compounds (Godlewska et al., 2019; Deng and Chow, 2010). Citric acid is required for various biological processes (Mudunkotuwa and Grassian, 2010). The citrate-nanometal complex can facilitate the entry of NPs along with citrate into the cell (Rupasinghe, 2011); hence the citrate form of nanometals has been recommended for the growth of plants (Chandrika et al., 2021). Some studies on plants have also shown that citrate reduces the adverse effects of nanoparticles (Tirani et al., 2018). Citrate can be adsorbed on the oxides of nanoparticles through Van der Waals bonds and prevent particles from aggregation (Park and Shumaker-Parry 2014; Rupasinghe 2011; Mudunkotuwa and Grassian, 2010).The aim of researchThe goal of this research was a comparative evaluation of the possible stimulating or adverse effects of bulk forms and nanoparticles of TiO2 (anatase and rutile), with or without citrate (in concentrations of 12.5, 25, 50, 100 and 200 mg. L-1) on the growth, biomass and intracellular compounds of microalgae S. platensis in 5 days. Materials and Methods Zarrouk nutrient medium was used for the growth of microalgae. Anatase nanoparticles 10-25 nm (Purity 99.9%, Specific surface area, SSA 200-240 m2 g-1), rutile nanoparticles 30 nm, (Purity 99.9%, SSA 35-60 m2 g-1) and bulk sample (diameter

The results of this study indicate that titanium dioxide nanoparticles (nano-TiO2) possess adsorptive, photocatalytic, bactericidal, virucidal and fungicidal properties, which are used in antibacterial coating, for air and water disinfection. In parallel with studies of the physicochemical characteristics of titanium dioxide, its toxicological assessment was carried out to prevent possible harmful effects on humans and the biosphere objects, followed by an assessment of the nano-TiO2 hazard class. To enhance these useful properties of nano-TiO2, nanopowders of titanium dioxide and a composite of titanium dioxide were synthesized with a silver (nano-TiO2 /Ag) by way of chemical precipitation of metatitanic acid adding silver nitrate to the composite at 500-600°C. It was stated that the synthesized nanostructures have the following characteristics: anatase crystal structure of TiO2 (anatase, rutile, brookite – natural crystalline modifications of TiO2), the size of Ag nanoparticles is 35-40 nm, TiO2 – 13-20 nm. Nanocomposite has surface defects of the crystal lattice (oxygen vacancies, impurities, excess electrons or holes), silver nanoparticles are localized on the surface of anatase TiO2, which increases adsorptive, photocatalytic, biological and specifically antibacterial properties of the composite material nano-TiO2/Ag. According to the parameters of acute intraperitoneal toxicity, the studied nanocomposite anatase nano-TiO2/Ag was classified as a moderately dangerous substance (material). Nano-TiO2 and TiO2/Ag nanocomposites do not cause local irritation to the skin, yet have a mildly irritating effect on the mucous membrane of the eye, and are also characterized by a weak sensitization effect.

Abstract In the present report, green synthesis of titanium dioxide nanoparticles (TiO2 NPs) was performed by upcycling mangosteen (Garcinia mangostana) pericarp extract (methanol and ethyl acetate extracts). Field emission scanning electron microscopy images revealed an aggregated structure with a highly porous network of TiO2 NPs. TiO2 NPs synthesized with ethyl acetate extract (EtOAc-TiO2 NPs) exhibited more monodispersity and possessed smoother surfaces than the control TiO2 NPs (Con-TiO2 NPs) and TiO2 NPs synthesized with methanol extract (MeOH-TiO2 NPs). High-resolution X-ray diffraction patterns clearly confirmed that TiO2 NPs had a crystalline nature. A mixture of anatase and rutile was observed in Con-TiO2 NPs and MeOH-TiO2 NPs, while EtOAc-TiO2 NPs had only anatase with the smallest size (12.50 ± 1.81 nm). Ethyl acetate extract contained the highest amount of α-mangostin; thus, the surface of TiO2 NPs was functionalized with ethyl acetate extract. The functionalized TiO2 NPs synthesized with ethyl acetate extract (EtOAc-TiO2-αm) showed the highest 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH) radical scavenging activity. In vitro cell viability on mouse fibroblast cells (NIH3T3) indicated that the newly synthesized TiO2 NPs did not show any significant cytotoxicity. Therefore, the TiO2 NPs in the present report have the potential to be used in cosmetic applications such as sunscreens.

In this work, a complete beneficiation technical route combining physical and chemical methods, namely a roasting-flotation-leaching scheme, is proposed to produce a qualified grade Ti-concentrate from altered Vanadium titanomagnetite (VTM) ore. Based on the character of the ore sample, it is recommended to recover the Ti-bearing minerals, ilmenite and anatase, as composite mineral. Pretreatment experiments indicate that the oxidation roasting (800 °C) and acid washing methods increase the flotation indexes significantly. Flotation condition tests show that the optimal conditions are a grinding fineness of −0.045 mm 83%, sulfuric acid dosage of 2000 g/t, water glass dosage of 1500 g/t, oxalic acid dosage of 200 g/t, and EM328 dosage of 1500 g/t. An open flotation circuit test obtains a flotation concentrate with a TiO2 grade and recovery of 38.30% and 25.99%, respectively. A leaching exploration test shows that the TiO2 grade of the flotation concentrate can be improved to 53.90%. XRD analyses reveal that the ilmenite in the VTM ore is converted into anatase and rutile during the roasting process at 600–800 °C, but pseudobrookite begins to form at 900 °C. Compared to the flotation concentrate, it is confirmed that the content of Ti-bearing minerals is increased significantly in the leaching residue.

The thermal conductivity of epoxy nanocomposites filled with self-assembled hybrid nanoparticles composed of multilayered graphene nanoplatelets and anatase nanoparticles was described using an analytical model based on the effective medium approximation with a reasonable amount of input data. The proposed effective thickness approach allowed for the simplification of the thermal conductivity simulations in hybrid graphene@anatase TiO2 nanosheets by including the phenomenological thermal boundary resistance. The sensitivity of the modeled thermal conductivity to the geometrical and material parameters of filling particles and the host polymer matrix, filler’s mass concentration, self-assembling degree, and Kapitza thermal boundary resistances at emerging interfaces was numerically evaluated. A fair agreement of the calculated and measured room-temperature thermal conductivity was obtained.

Although TiO2 nanotubes is a promising electrode as supercapacitors due to its high energy density, easy synthesis and chemical stability, there are draw backs such as low conductivity and capacitance. Many studies concentrated on improving its electrochemical performance itself but little attention was payed to the reason of capacitance differences caused by its different crystal structures. Herein, we prepare amorphous and anatase TiO2 nanotubes and hydrogenated them by a simple electrochemical hydrogenation method to improve their conductivity and capacitance. And then study and compare their morphology and structure differences by SEM, TEM, XRD and BET. The results show that the pore size distribution, internal structure order and internal carrier concentration are the main reasons for their electrochemical performance differences. The microporous structure less than 2 nm in amorphous nanotubes act as a trap of electrolyte ions at current density larger than 0.1 μA cm−2, leading to small charge and discharge capacitance. The long-range ordered crystal structure of anatase is more favorable for the orderly diffusion of carriers, reducing the inelastic scattering of carrier diffusion process and the electron hole-complexing probability, making anatase nanotubes exhibit higher coulomb efficiency and cycle stability than that of amorphous ones.

The dioxide titanium (TiO2) is attracting a great attention as semiconductor photocatalyst because of its high photoreactivity, non-toxicity, corrosion resistance, photostability, cheapness. It can be used in wide range of applications: air and water purification, hydrogen (H2) generation, CO2 reduction, in photovoltaic application and others. The efforts of scientists were applied to use solar light for dioxide titanium photocatalysis and to enhance the photocatalytic efficiency. In this article we review the properties difference of anatase and rutile modifications of TiO2. The anatase has a higher photoefficiency. The higher photoefficiency of anatase is due to longer lifetime of charge carriers (lifetime of e-/h+ in anatase on 3 order higher than in rutile). But anatase has higher band gap energy (3.2 eV or 388 nm) in comparison with rutile (3.0 eV or 414 nm). Thus, anatase becomes photosensitive in ultraviolet (UV) diapason of light, meanwhile rutile - in violet spectrum of visible light. It is desirable to obtain TiO2 semiconductor with properties combining best ones from anatase and rutile: higher photoreactivity and smaller band gap. It can be made by using external factors such as electric or magnetic fields, doping and etc.

To prevent implant-associated infections, surface modifications need to be developed that prevent bacterial colonisation and biofilm formation. In the present study, titanium surfaces were processed by nanosecond-pulsed laser ablation to generate a variety of different structures (anatase, rutile, Osteon, as well as Osteon additionally coated with silver and clove nanoparticles). Analysis of adhesion and biofilm formation of the oral pioneer bacterium Streptococcus oralis could demonstrate antibacterial properties of anatase surfaces. For clinical translation, the effect should be enhanced by further adaption and combined with the osseointegrative Osteon structure

Abstract Titanium dioxide is a widely studied material with well-known applications for anatase and rutile phases. Moreover, brookite, another polymorph, which is more difficult to obtain, has caught scientific community interest, especially for photocatalysis applications. Among many methodologies for TiO2 synthesis, the hydrothermal method stands out, with the possibility of controlling different parameters that lead to a specific phase composition, allowing selective polymorphic obtainment. This method was used to synthesize TiO2 with different anatase/brookite ratios, by the use of different synthesis conditions as pH of the suspension, sodium salt concentration, and temperature, resulting in anatase-brookite photocatalyst with brookite composition ranging from 0 to 35%. The materials were characterized by X-ray diffraction, infrared spectroscopy, Raman spectroscopy, particle size measurement, and scanning electron microscopy. Photocatalysts with the highest brookite amount showed the best photocatalytic results for Remazol golden yellow (RNL) dye decolorization. Moreover, the short-range disorder also played an important role in photocatalytic behavior.