Titania Content Research Articles

New insight into the role of crosslinkers and composition on selectivity and kinetics of antimony uptake by chitosan-titania composite beads

Role of composition and the nature of crosslinking on the properties of titania-chitosan beads have been investigated in detail. The investigations were done in order to explore the feasibility of design and synthesis of titania-chitosan beads with bespoke functionality based on the intended application. This would greatly enhance the potential for the industrial application of these biopolymer based beads. Beads of varying compositions (of titania and chitosan) were prepared and crosslinked using epichlorohydrin or glutaraldehyde. The physical characteristics and antimony binding properties of the resultant crosslinked titania-chitosan beads were investigated in detail. Influence of chitosan amount on swelling was seen to be more predominant in the glutaraldehyde crosslinked beads (TA-Cts-Glu). TA-Cts-Glu beads showed more swelling and better antimony (Sb(III) and Sb(V)) uptake as compared to the epichlorohydrin crosslinked beads (TA-CTS-Epi). While TA-Cts-Glu beads showed faster uptake kinetics compared to the TA-CTS-Epi beads, the latter showed selectivity towards Sb(III) against transition metal cations. Further, the beads exhibited differential uptake of Sb(V) and Sb(III). TA-Cts-Glu beads prepared with equal amounts of titania and chitosan showed the maximum Sb(V) uptake while the TA-Cts-Epi beads with higher chitosan to titania ratio showed the least. Sb(V) binding was enhanced by the crosslinked chitosan, while the Sb(III) uptake was aided predominantly by the titania content in the beads.

Titanium-Modified MIL-101(Cr) Derived Titanium-Chromium-Oxide as Highly Efficient Oxidative Desulfurization Catalyst

A titanium-chromium-oxide catalyst was prepared by a facile calcination of titanium-modified MIL-101(Cr). The resulting material, possessing a surface area of 60 m2 g−1 and a titania content of 50.0 wt%, can be directly used as the catalyst for oxidative desulfurization (ODS) reaction of dibenzothiophene (DBT). This novel ODS catalyst can remove 900 ppm sulfur-containing compounds in a reaction time of 30 min at 60 °C. The experimental results showed that the specific activity increased with the titanium content. The specific activity of the catalyst with 50%Ti reached 129 μmol/m2, which was much higher than that of reported Ti-based catalysts.

Effect of TiO2 in supported NiWS catalysts for the hydrodeoxygenation of guaiacol

A series of NiWS catalysts supported on TiO2, ZrO2 and TiO2-ZrO2 mixed oxides was tested in the hydrodeoxygenation of guaiacol. The TiO2/ZrO2 ratio in the mixed oxides was varied to elucidate the effect of the titania content on the catalyst activity. According to our results, high acidity values seem to favor the demethylation route with catechol as the main product, while a medium acid strength could probably be the active site for the scission of the Caromatic-OCH3 bond. Moreover, the production of completely deoxygenated compounds was directly related with the TiO2 percentage on the catalysts. In this sense, guaiacol needs to be converted by the demethoxylation route, in order to avoid the catechol formation, which is a coke precursor, and phenol production route is improved. A fair correlation between medium acid strength for the catalysts and the phenol formation was also found. The catalyst supported on TiO2 was found to be the most active per atom of metal, 62% higher than the NiW/TZ(80/20) catalysts. The content of titania on the support was relevant to obtain completely deoxygenated compounds, such as cyclohexane and benzene.

ROLE OF FRICTION ENERGY AND TRIBO-REDUCTION IN ABRASIVE WEAR OF ALUMINA–TITANIA COATINGS

This paper addresses friction energy-induced reduction of TiO2 during abrasive wear and friction of alumina–titania coatings with different TiO2 content. Alumina–13% titania and alumina–40% titania coatings were deposited by atmospheric plasma spray technique. An improvement in fracture toughness and better densification of coatings was observed with an increase in titania content. Alumina–40% titania coating showed lower friction coefficient and higher abrasive wear resistance than alumina–13% titania coating. An increase in friction energy was associated with enhanced reduction of TiO2 to Ti2O3 and an increase in the extent of gamma alumina to alpha alumina phase conversion. These observations along with structural and mechanical properties of coatings could explain differences in tribological response of these coatings. Friction energy parameter (FEP) was used to identify different regimes of wear and degradation mode of coatings.

Robust interface on ENR-50/TiO2 nanohybrid material based sol-gel technique: Insights into synthesis, characterization and applications in optical

In this work, the sol–gel technique was used to prepare a new organic–inorganic hybrid from Epoxidized Natural Rubber (ENR-50) and Titanium dioxide (TiO2) by blending different content of titania precursors (10, 30, and 50 wt%) with an ENR-50 matrix. A wide range of analyses was conducted to understand the nature of this hybrid and also to evaluate its potential uses in applications required high refractive index such as micro optical and optoelectronic devices. Results indicated that the ring-opening reaction of epoxide groups in ENR-50 increased with the increase of titania content in the hybrid resulting a strong bonding between titania and ENR-50 through TiOC bond, which was observed in FTIR spectrum at 1027–1028 cm−1. It is also observed a slight decrease in the intensity of the amorphous peak along with a new crystalline peak appeared at 2θ = 23 and 27° due to the crystalline nature of titania. The hybrids showed three thermal degradation steps in the range of temperature 76 to 769 °C due to the existence of the Ti moieties with the mixture of polymer chains, which in turn shifted the Tg at 24.3, 26.9 and 28.1 °C for the hybrid at 10, 30, and 50 wt% TiO2 compared to the Tg of ENR-50 at −18.4 °C respectively. The morphology of the ENR-50 showed clear changes during of the synthesis of ENR-50/TiO2 hybrids, these changes were proven by SEM, TEM, and AFM analyses. Uv–Vis results showed that the higher wavelength peak at 293 nm has shifted to 296, 298 and 300 nm for the hybrid at 10, 30, and 50 wt% TiO2 respectively due to the strong interaction between titania precursors and ENR-50 matrix. Furthermore, the hybrids showed good optical transparency in the visible light range.

Cellulose/Poly(vinylidene fluoride hexafluoropropylene) composite membrane with titania nanoparticles for lithium-ion batteries

In this work, porous Cellulose/Poly (vinylidene fluoride hexafluoropropylene) membrane with the incorporation of different amount of titania nanoparticles is prepared by non solvent induced phase inversion (NIPS) method followed by hydrolysis with lithium hydroxide for deacetylation of cellulose acetate. The composite membranes provide interconnected porous structure with high porosity. Titania incorporation and surface modification of Poly (vinylidene fluoride hexafluoropropylene) in the membrane are investigated by Fourier-transform infrared absorbance and transmission tests. The results show that the modified membrane exhibits excellent thermal stability at 200 °C with just only 1% shrinkage and contains high ion conductivity (1.68 mS cm−1). Moreover for window 2.5–4.5V, the ceramic nanoparticles embedded membrane with optimal titania content enables the battery to deliver 97.34% capacity retention after running 100 cycles at 1C rate and to maintain the capacity up to 72% even for 500 cycles after continuing different cycling test with Lithium cobalt oxide/Lithium cell assembly.

The effect of MgO addition on the properties of alumina-based ceramic cores prepared via sol–gel process

Alumina-based ceramic cores with MgO addition were prepared using sol–gel process. Prior to magnesia addition, the suitable amount of titania content was determined in the previous research, where it was found that the body with 15 wt% titania had the most suitable properties. The effect of magnesia addition on mechanical, physical, thermal, chemical, and microstructural properties of the cores was investigated through adding MgTi2O5 and sintering the bodies at two temperatures (1400 and 1500 °C) for two different soaking times (1 and 2 h). According to the results of flexural strength test, apparent porosity measurement, leaching test, and microstructural properties of the sintered bodies, the body which contained 15 wt% titania and 4 wt% magnesia had the least sintering shrinkage (~2%), suitable apparent porosity (~30%), acceptable flexural strength (40 MPa), good thermal expansion coefficient (~4.3 × 10−6 °C−1), and also exhibited a suitable leaching behavior.

Effect of the Compositions on the Biocompatibility of New Alumina-Zirconia-Titania Dental Ceramic Composites.

Dental implant biomaterials are expected to be in contact with living tissues, therefore their toxicity and osseointegration ability must be carefully assessed. In the current study, the wettability, cytotoxicity, and genotoxicity of different alumina–zirconia–titania composites were evaluated. The surface wettability determines the biological event cascade in the bioceramic/human living tissues interface. The measured water contact angle indicated that the wettability strongly depends on the ceramic composition. Notwithstanding the contact angle variability, the ceramic surfaces are hydrophilic. The cytotoxicity of human gingival fibroblast cells with materials, evaluated by an (3-(4,5 methylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) test, revealed an absence of any cytotoxic effect. A relationship was found between the cell viability and the wettability. It was subsequently deduced that the cell viability increases when the wettability increases. This effect is more pronounced when the titania content is higher. Finally, a comet test was applied as complementary biocompatibility test to detect any changes in fibroblast cell DNA. The results showed that the DNA damage is intimately related to the TiO2 content. Genotoxicity was mainly attributed to ceramic composites containing 10 wt.% TiO2. Our research revealed that the newly developed high performance alumina–zirconia–titania ceramic composites contain less than 10 wt.% TiO2, and display promising surface properties, making them suitable for dental implantology applications.

Vapour-phase conversion of methyl lactate into lactide over TiO2/SiO2 catalyst at the lowered pressure

Now polylactide (PLA) widely use as biodestructive packing material. Usually monomeric lactide produce from lactic acid. Also, methyl (ethyl) lactate could be used for lactide obtaining via its vapour-phase condensation on TiO2/SiO2 catalyst at 2600C in N2 carrier-gas flow. However, at that it is necessary to heat carrier-gas to the reaction temperature. In this communication the results on methyl lactate vapour condensation into lactide with the lowered pressure of 100-150 mbar, without carrier-gas, are presented. Supported TiO2/SiO2 catalyst with 5 wt.% titania content has been prepared by impregnation of silica with Ti(OC4H9)4. After calcination at 5000C prepared catalyst has amorphous mesoporous structure with 335 m2/g surface area and 0.83 сm3/g pore volume. The catalytic experiments were performed in such way. Liquid methyl lactate was dosed into the evaporator (2500C) and further in the flowing reactor (2600C) under pressure of 100 mbar that produced by vacuum pump. Load on a catalyst was varied from 25 to 55 mmol ML/(gcath). Cooled product was analyzed on Agilent 7820A chromatograph and NMR Bruker Avance-400 spectrometer. It was shown that TiO2/SiO2 catalyst provide 74% selectivity towards lactide at 50-53% methyl lactate conversion with lactide productivity of 7.8 mmol L/(gcath) at 2600C/100 mbar. The catalyst stable work is more 80 h. Main impurities are methyl lactoillactate, 1-methoxyethanol and 1,1-dimethoxyethane.

Effects of micro‐nano titania contents and maleic anhydride compatibilization on the mechanical performance of polylactide

AbstractThe first aim of this study was to compare influences of various contents of the micro‐ (200 nm) and nano (50 nm)‐sized titania (TiO2) particles especially on the mechanical performance of the polylactide (PLA) biopolymer. Micro‐ and nano‐composites were prepared by twin‐screw extruder melt mixing, while the specimens were shaped by compression molding. Scanning electron microscope analyses and mechanical tests revealed that due to the most efficient uniform distribution in the matrix, the best improvements in the strength, elastic modulus, and fracture toughness values could be obtained either by using 5 wt% micro‐TiO2 or by only 2 wt% nano‐TiO2 particles. The second purpose of this study was to investigate influences of using maleic anhydride (MA)‐grafted copolymer (PLA‐g‐MA) compatibilization on the performance of one nanocomposite composition. Due to the improved chemical interfacial adhesion, use of PLA‐g‐MA compatibilization for the specimen of PLA/2 wt% n‐TiO2 composition resulted in the highest improvements in the mechanical performance of neat PLA. The improvements were 14% in tensile strength, 20% in flexural modulus, and as much as 67% in fracture toughness. Thermal behavior of all specimens was also observed by differential scanning calorimetry and thermogravimetric analyses.

Geochemistry and geodynamic setting of Paleoproterozoic granites of Lesser Garhwal Himalaya, India

The granite and gneisses rocks are well exposed around Toneta, Tilwara and Chirbatiyakhal region in the Lesser Garhwal Himalaya have less studied which consider as Paleoproterozoic age. The granites from Toneta area are classified as K-rich peraluminous granite with low Na2O varies from 0.85 to 2.4 wt.% and high K2O content varies from 5.0 to 6.9 wt.%. The average Al2O3 (14.16 wt.%) in the granite is greater than the total alkalies (Na2O+K2O = Av. 7.62 wt.%), the Titania (TiO2) content is low ranging from 0.1 to 0.28 wt. %. In the Y + Nb – Rb, Y – Nb, Ta + Yb – Rb, and Yb – Ta discrimination diagram of Pearce et al. (1984) show that the Toneta granites mostly plots within the syn-collision granite fields. This is typical collisional granite.

Energy and electron transfer reactions on silica gel and titania\u2013silica mixed oxide surfaces

The energy and electron transfer reactions of anthracene co-adsorbed with an electron donor on silica gel and titania–silica mixed oxides have been studied by a combination of steady-state reflectance, emission spectroscopy, and nanosecond diffuse reflectance laser flash photolysis. Bimolecular rate constants for energy and electron transfer between anthracene and azulene have been measured; kinetic analysis of the decay of the anthracene triplet state and radical cation show that the kinetic parameters depend on the titania content of the sample and the azulene loading. The rate of energy and electron transfer reactions increases as a function of azulene loading and decreases with increasing titania content in titania–silica mixed oxides. These findings indicate that the observed rate of reaction is determined by the rate of diffusion of anthracene on the titania–silica surfaces, whereas, in contrast, the observed rate of reaction on silica gel is predominantly governed by the rate of diffusion of azulene.Graphic abstract

Development, Synthesis, and Study of Nanomaterials of Titania Doped by Zirconium for Selective Hydrogenation of 2-Methyl-3-Butyn-2-ol in a Microcapillary Reactor

An ordered mesoporous titanium–zirconium TixZr1–xO2 matrix for introducing catalytic nanoparticles was synthesized by self-assembly using titanium isopropoxide and zirconium oxychloride as precursors and amphiphilic triblock copolymer F127 as a template. The process of self-assembly occurs without the addition of an acid to preserve the morphology and structure of the catalytic nanoparticles. When controlling the initial molar ratios of the copolymer to metal precursors, titanium–zirconium nanocomposites with controlled texture and composition were obtained in a wide range of titania content, from 15 to 80 mol % TiO2. The structural and phase properties of the composites were studied by X-ray diffraction, low-temperature nitrogen adsorption, and transmission electron microscopy. Composites have an ordered mesoporous structure, a high specific surface area, a large pore volume, and a uniform pore size distribution. Catalytic coatings of 1 wt % Pd–Zn/TixZr1–xO2 (x = 1.0, 0.8, 0.5) on the inner surface of a capillary reactor were prepared by the dip-coating method using a colloidal solution of Pd–Zn nanoparticles. The developed catalytic coatings based on titanium–zirconium composites exhibit high activity and selectivity (> 96%) in the hydrogenation of 2-methyl-3-butyn-2-ol.

Electrodeposition of Ni–TiO2 Composite Coatings Using Electrolyte Based on a Deep Eutectic Solvent

Deep eutectic solvents are nowadays considered to be very promising analogues of room temperature ionic liquids. They can make a significant contribution to the development of novel efficient, economic and environmentally friendly processes, particularly, in surface engineering and electroplating. The electrodeposition of Ni–TiO2 composite coatings from an electrolyte based on a deep eutectic solvent, ethaline, was studied in this work. Titania particles were introduced into the plating bath in the form of Degussa P 25 nanopowder. The content of titania in electrodeposited composite coatings was shown to depend on the stirring rate, current density and TiO2 concentration in the electrolyte and can reach ca. 2.35 wt %. The microstructure and the surface morphology of the obtained composite layers were characterized. The formation of nanocrystalline nickel matrix was detected. The introduction of TiO2 particles into nickel-based coatings resulted in an increase in the microhardness of deposits. The data obtained via the electrochemical impedance spectra technique revealed an improvement in the corrosion resistance of coatings due to titania particles incorporation into deposits. The Ni–TiO2 composite coatings manifested a photocatalytic activity towards the reaction of photochemical degradation of methylene blue organic dye in water solution.

Microwave solvothermal carboxymethyl chitosan templated synthesis of TiO2/ZrO2 composites toward enhanced photocatalytic degradation of Rhodamine B

A series of TiO2/ZrO2 composites with various molar ratios of ZrO2:TiO2 were synthesized by a facile and mild microwave hydrothermal method with carboxymethyl chitosan (CMCS) as templates. The as-obtained products were characterized with wide-angle powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), UV–vis diffuse reflectance spectrophotometry (UV–vis-DRS), N2 adsorption-desorption isotherms (BET), and X-ray photoelectron spectrometer (XPS). The TiO2/ZrO2 composites with heterogeneous structure consisted of particles which showed a better regularity and uniform with about 800 nm in diameter, and showed a larger specific surface area and smaller energy band gap than pure ZrO2. Comparative experiments including varying the pH of the solution and the content of titania demonstrated that the 5% TiO2/ZrO2 composites (nTi:nZr = 5:100) at pH = 10.3 possessed the best photocatalytic property. Moreover, the possible reasons for these phenomena were clarified. Cyclic experiments proved that the resulting TiO2/ZrO2 composites as photocatalyst could be reused efficiently. Meanwhile, a possible mechanism of photocatalysis was proposed.

Effect of powder grain size and titania content on mechanical and tribological properties of plasma sprayed Al2O3-TiO2 ceramic coatings

Effect of powder grain size and titania content on mechanical and tribological properties of plasma sprayed Al2O3-TiO2 ceramic coatings

Modelling of adsorption/photodegradation phenomena on AC-TiO2 composite catalysts for water treatment detoxification

A numerical model has been established to get insight the mechanism of phenol removal from water through adsorption/photodegradation dual process over activated carbon titania composite catalysts (AC-TiO2). AC-TiO2 catalysts were obtained through a straightforward coating of a homemade AC with titania nanoparticles (TiO2-NPs), and their textural characterization revealed the presence of titania nanoparticles (TiO2-NPs) scattered at the external macroporosity of the microporous AC support material. A new mathematical approach were established to comprehensively take into account the bulk/por /surface diffusion rate of the pollutant before adsorption within the microporous catalyst, and then intrinsic photodegradation near the externally located and UV accessible TiO2-NPs. Under different experimental conditions and using catalysts of different titania contents, the simulated kinetics readily fit well the experimental profiles, suggesting the actual application of the model to describe the adsorption/photodegradation dual process driven by the composite catalysts.

Photocatalytic Properties of ZnO-TiO<sub>2</sub> Composite Films Prepared by Spray Pyrolysis

Thin films of ZnO, ZnO coated with TiO2 and ZnO modified with titania were prepared by using simple spray pyrolysis of zinc and titanium containing solutions. The photicatalytic activity of the obtained films was determined by degradation of MB solution under UV and simulated solar illumination. The photocatalytic activity of ZnO/TiO2 films depended on the content of titania, substrate surface roughness, surface area and deposition cycles. The highest activity under simulated solar light was detected for ZnO films containing 3 wt.% of TiO2.

Influence of the Titania Content on the Microstructure and Properties of Plasma Sprayed Alumina-Titania Coatings

The composite alumina-titania coatings have been widely used in industry fields to protect metallic components from wear, corrosion and thereby prolonging their service time. This paper presents an analysis of the microstructure and mechanical properties of Al2O3-TiO2 composite coatings, plasma sprayed on steel substrates from feedstocks containing various concentrations of the TiO2 powder. The coatings revealed lamellar microstructure, formed by the rapid solidification of molten droplets of the powder on previously deposited splats. The main phase identified in the coatings was γ-Al2O3 phase, the others were TiO2 and α-Al2O3, as well as amorphous phase. The results indicated significant improvement of hardness, Young’s modulus and fracture resistance of coatings with an increase in TiO2 from 3 wt. % to 13 wt. %. The friction coefficient was found to be the same for both coatings.

Preparation and characterization of hydroxyapatite/titania nanocomposite coatings on titanium by electrophoretic deposition

Hydroxyapatite (HA)/titania nanocomposite coatings with varied compositions were fabricated by electrophoretic deposition (EPD) method on titanium substrates. The EPD kinetics decreased more prominently with time in case of suspensions with higher amount of titania nanoparticles. The cracking induced by sintering decreased and finally completely disappeared by increasing the titania content in the suspensions (≥50 wt%). The adhesion strength of coatings also increased with titania content in suspensions. Cell culture experiments showed that the coating deposited from the suspension with 50 wt% of titania nanoparticles has the highest cell growth efficiency. Considering the results obtained by microstructural (crack formation), adhesion and cell culture analysis, the coating deposited from the suspension with 50 wt% of titania nanoparticles was regarded as the optimum. The optimum coating showed high bioactivity and its surface covered completely with thick apatite layer after soaking in simulated body fluid (SBF) for 1 week. The application of optimum coating on the titanium substrate considerably decreased its corrosion rate in SBF.