Synthesis Of TiO2 Powders Research Articles

Flash combustion synthesis using two different fuels and characterization of LiF-doped TiO2 for the photocatalytic applications

The flash combustion method was used to prepare LiF-doped TiO2 photocatalysts materials using glycine or urea as a fuel with different weight percentage of LiF. The synthesized powders have been characterized by thermogravimetric analysis (TG), scanning electron microscope (SEM) with energy dispersive spectrometer (EDX) analyzer, the specific surface area measurement was performed by BET. The crystallization and the phase transformation anatase-rutile for the powders have been verified by XRD. SEM micrographs for these powders shows the presence of nanoparticles. To investigate the optical band gap of the synthesized samples, UV–Vis spectroscopy was conducted using the diffuse reflectance mode (DRS). The O2−/F− substitution and the presence of Ti3+ centers was confirmed by electron paramagnetic resonance (EPR) analysis. The photocatalytic activity of the TiO2-xLiF powders were evaluated through the photocatalytic degradation of Methylene blue (MB) in water under UV–visible light exposure. The results indicated that during the flash combustion synthesis, the nature of the fuel and the percentage of the doping element led to the presence of different polymorphs of TiO2 which influences the photocatalytic efficiency attributed to the synergistic effect between the two phases (anatase and rutile). The LiF-doped TiO2 powders synthesized by flash combustion in both cases (by using glycine or urea) showed high performance in MB degradation compared to commercial TiO2 and undoped synthesized TiO2 powders, with an optimal degradation of 99 % achieved with 2 wt % LiF-doped TiO2 using glycine as a fuel and after 6 h of UV–Vis irradiation.

SYNTHESIS OF TIO2 BY SOLVOTHERMAL METHOD AND ITS PHOTOCATALYTIC ACTIVITY TOWARDS BISEPTOL AND CONGO RED

The creation of ceramic membranes with additional functional properties, such as antibacterial and photocatalytic, is a popular and promising area of research in the field of water treatment. The article is devoted to the synthesis of titanium (IV) oxide powders by the solvothermal method for their further usage as a photocatalytic selective layer in ceramic membranes. The study of the peculiarities of the photocatalytic materials synthesis for the creation of photocatalytic and at the same time antimicrobial ceramic membranes on their basis is extremely relevant, because it will allow to develop a method of synthesis of photocatalysts active to various pollutants. Therefore, the aim of the work was the synthesis of TiO2 powders by solvothermal method at different ratios of the starting reagents, the study of their physicochemical properties and the study of their photocatalytic properties in relation to different pollutant – antibiotics and dyes. The obtained powders were characterized by diffraction analysis, infrared spectroscopy, low-temperature nitrogen adsorption-desorption and scanning electron microscopy. It is established that the ratio of the initial components significantly affects the final properties and characteristics of TiO2 powders. It was shown that the synthesis with a significant excess of the starting reagent (titanium isopropoxide) does not lead to the crystalline TiO2 sample, which was confirmed by diffraction analysis and infrared spectroscopy. The revealed porous structure of all TiO2 samples indicates a high specific surface area in them, which is also consistent with scanning electron microscopy studies. The highest photocatalytic activity is possessed by TiO2 samples, which are nanocomposites of anatase and rutile modifications. Such nanocomposites showed quite high activity towards antibiotics (Biseptol) and anionic dyes (Congo red).

Fabrication of DSSC photoanode based on TiO2 produced by caustic fusion of local ilmenite

Photoanode is an essential part in dye sensitized solar cells (DSSC). Semiconductor materials, such as TiO2, ZnO, and SnO2, are commonly used as photoanode material. In this study, DSSC photoanode was fabricated using TiO2 obtained from Bangka ilmenite concentrate by caustic fusion method followed by water leaching, acid leaching, and sol-gel reactions. The synthesized TiO2 powder has an anatase phase with a crystal size of 9.55 nm, band gap energy of 3.0 eV, spherical morphology with an average particle size of 0.53 μm, and a specific area of 138.39 m2/g. The synthesized TiO2 powder was found to have Fe impurities. The DSSC with TiO2 photoanode synthesized in this work produced current-voltage characteristics with photoconversion efficiency of 0.75%.

Plasma dynamic synthesis of highly defective fine titanium dioxide with tunable phase composition

Titanium dioxide is currently one of the most known promising photocatalysts. However, its use in the visible light range is limited due to its high energy gap. In this work, to solve the mentioned problem, it is proposed to obtain highly defect structures of titanium dioxide by means of a high-energy plasma dynamic synthesis method. It possible to synthesize TiO2 Titanium dioxide powders with a tunable ratio of rutile and anatase modifications, as well as a particle size distribution were synthesized, by optimizing the synthesis conditions, including the process energy and parameters of the gaseous medium. The formation of shock-wave structures in the pulsed synthesis process results in obtaining fine particles of rutile and anatase with a highly defective crystal structure. The final product was revealed to have an extended working absorption spectrum region and a reduced band gap (2.74 eV). A possibility of photocatalytic applications for the synthesized TiO2 powder was demonstrated in measurements of photocurrent density with time (j-t) under intermittent visible light irradiation.

New Formulation of TiO<sub>2</sub>- ZnO Slurry for Facial Foundation Sunscreen Cream Application

The objective of this research was to prepare ready-to-use TiO2 and ZnO in slurry form for ready-to-use in facial foundation sunscreen. Two types of TiO2 sources were prepared as TiO2 slurry namely commercial TiO2 powder and synthesized TiO2 powder. Preparation of formula 1, 35 g solution PEG-10 dimethicone, and added 20 g solution cyclomethicone after that 45 g TiO2 powder was added slowly to the prepared substance, stirring and heated to 60-70 °C, and stir until the substance mix well. Formula 2, 46 g solution cyclomethicone added 2.5 g stearic acid and 2 g aluminum hydroxide after that stirring and heated to 60-70 °C until the substance mixed well, and TiO2 powder 49.5 g was added slowly to the continuous stirred and heated. On the other hand, ZnO slurry was prepared in the same steps. The results show that formula 1was the best formulation. Due to it was not precipitation and good compatibility with an emulsifier, therefore, formula 1was chosen to study in various volumes. The texture and stability of the prepared slurry were similar to the commercial slurry. Two sunscreen formulas were differently formulated by containing prepared and commercial slurry and evaluated. There were no significant differences in results between prepared slurry and commercial slurry. To investigate the satisfaction of products, 30 volunteers were asked to use products for one week and answer the questionnaires. The product containing prepared slurry was satisfied by 93.33% of volunteers, whereas the product containing commercial slurry was satisfied by 76.66% of volunteers.

Physicochemical, optical, and photocatalytic properties of titanium dioxide modified with zinc oxide nanoparticles synthesized by a pulsed plasma chemical method

In this study, particles of titanium dioxide (TiO2) were modified with particles of zinc oxide (ZnO) using a pulsed plasma chemical method, with ZnO initially being obtained by an electrospark method. The particle size of the synthesized TiO2 powder modified with ZnO nanoparticles ranged from 30 to 100 nm. The morphology of the nanoparticles was found to be diverse, mainly represented by spheres, ovals, and parallelograms. The phase composition was a mixture of crystalline phases characteristic of TiO2 (rutile and anatase) and ZnO, with the predominant phase being anatase. The presence of Zn–O–Ti bond is typical for all samples of TiO2 powder modified with ZnO nanoparticles prepared using a pulsed plasma chemical synthesis, which indicates the formation of a solid solution. The optical and photocatalytic properties of the modified nanoparticles were also studied, as well as the band gap was determined. For some samples, a narrowing of the band gap was recorded. The samples showed high photocatalytic activity in the decomposition of methylene blue under the influence of ultraviolet and visible light in the wavelength range of 400–630 nm. Methylene blue degradation efficiency was 66% in visible light spectrum.

Characterization and A Preliminary Study of TiO<sub>2</sub> Synthesis from Lampung Iron Sand

The purpose of this study is to characterize Lampung iron sand and to conduct preliminary experiments on the TiO2 synthesis which can be used for the manufacturing of functional food packaging. The iron sand from South Lampung Regency, Lampung Province that will be utilized as raw material. The experiment was initiated by sieving the iron sand on 80, 100, 150, 200 and 325 mesh sieves. Analysis using X-Ray Fluorescence (XRF) to determine the element content and X-Ray Diffraction (XRD) to observe the mineralization of the iron sand was conducted. The experiment was carried out through the stages of leaching, precipitation, and calcination. Roasting was applied firstly by putting the iron sand into the muffle furnace for 5 hours at a temperature of 700°C. Followed by leaching using HCl for 48 hours and heated at 105°C with a stirring speed of 300 rpm. The leaching solution was filtered with filtrate and solid residue as products. The solid residue was then leached using 10% H2O2 solution. The leached filtrate was heated at 105°C for 40 minutes resulting TiO2 precipitates (powder). Further, the powder was calcined and characterized. Characterization of raw material using XRF shows the major elements of Fe, Ti, Mg, Si, Al and Ca. The highest Ti content is found in mesh 200 with 9.6%, while iron content is about 80.7%. While from the XRD analysis, it shows five mineral types namely magnetite (Fe3O4), Rhodonite (Mn, Fe, Mg, Ca) SiO3, Quart (SiO2), Ilmenite (FeOTiO2) and Rutile (TiO2). The preliminary experiment showed that the Ti content in the synthesized TiO2 powder is 21.2%. The purity of TiO2 is low due to the presence of Fe metal which is dissolved during leaching, so that prior to precipitation purification is needed to remove impurities such as iron and other metals.

Fabrication Of TiO₂ Nanoflowers Powder with Various Concentration Of CTAB

Nanostructures titanium dioxide (TiO₂) such as nanoflowers and nanorods have contribute in many application. Among TiO₂ nanostructures, TiO₂ nanoflowers gives high surface area that contribute in good binding properties and reducing internal stress and increasing strength of the ceramics.This paper presents fabrication of TiO₂ nanoflowers powder to overcome the cracking problem in ceramic industry. In this study, fabricated rutile- phased TiO₂ nanoflower powder has been successfully synthesized by using hydrothermal method and the surface morphology, structural properties, and the composition of TiO₂ nanoflower powder also identified. The fabricated TiO₂ are characterized using Field Emission Scanning Electron Microscopy (FESEM) to observe the surface morphology of TiO₂, X-ray Dispersion (XRD) was used to determine the crystallite phase and EDX for element composition in fabricated TiO₂ powder. The synthesized TiO₂ powder was obtained from the reaction between deionized water (DI), hydrochloric acid (HCl), Titanium Butoxide (TBOT) and Cetyltrimethylammonium Bromide (CTAB). The hydrothermal temperature is 150 C̊with fixed hydrothermal time of 10 hours. The parameters varied is the mass of surfactant used, CTAB. The hydrothermal method is proven suitable to fabricate semiconductor materials due to its advantages that parameters are easily modified and can be performed under closed system with low operational temperature. Increased amount of CTAB used make the gap between the nanorod become closer and stronger. The diffraction peaks of all sample hardly changed, but the intensity for each sample was enhanced as the mass of CTAB used increased. The structure also become well crystallined in rutile phase structure.

Facile Synthesis of TiO2 Nanoparticles of Different Crystalline Phases and Evaluation of Their Antibacterial Effect Under Dark Conditions Against E. coli

In this paper we report the antibacterial activity in the absence of UV–Vis irradiation of TiO2 nanoparticles, in amorphous, anatase and rutile phases, obtained by the sol–gel process, on Escherichia coli strains. The synthesized TiO2 powders were characterized using X-ray diffraction (XRD), IR spectroscopy and UV–Vis absorption, as well as scanning and transmission electron microscopies. The XRD results showed that the solids were amorphous up to a temperature of 350 °C and that when subjected to heat treatments of higher temperatures, anatase crystalline phases were obtained, at 450 °C, and rutile type at temperatures higher than 770 °C, with a sub-micron particle size (< 1 μm) and varying morphology. The inactivating effect on bacteria of synthesized TiO2 was analyzed by recording the effect of its presence on bacterial strains of E. coli. To this end, the synthesized TiO2 in its amorphous (am-TiO2), anatase (a-TiO2) or rutile (r-TiO2) phases, at different concentrations, was incorporated into the E. coli cultures, placing aluminum foil over the strains to simulate darkness. Although all the phases of the TiO2 synthesized present reasonable antibacterial activity, the highest efficiency is seen in the cultures treated with r-TiO2.

Effects of reagents on the formation of nanoparticulate titanium dioxide synthesized by sol-gel technique

Photocatalytic properties of titanium dioxide are generally enhanced through formation of nanometer-sized anatase Titanium dioxide (TiO2) phase but to achieve the desired chemical composition and particle size, appropriate selection of initial reagents are required. This study was conducted to examine the effects of the initial reagents, specifically titanium (IV) isopropoxide (TTIP), sub-micrometer-sized TiO2 dissolved in sulfuric acid (H2SO4), and TiO2 dissolved in H2SO4 with added polyacrylic acid, on the chemical compositions and particle sizes of the sol-gel synthesized TiO2 powder. Results indicated that synthesis of TiO2nano-particulates with the respective average sizes of 48 and 85 nm was achievable using TTIP or sub-micrometer-sized TiO2 dissolved in H2SO4 with added polyacrylic acid as initial reagents.. In the absence of polyacrylic acid, the formation of an additional secondary phase and the production of larger particles averaging 130 nm in size were observed. Results of the antibacterial test capability of the synthesized TiO2 also pointed out that powder synthesized from sub micrometer-sizedTiO2 dissolved in H2SO4 with polyacrylic acid added also proved that it is capable of reducing Staphylococcus aureus by more than 99.9%, suggesting that it could be a cost effective replacement for the more expensive TTIP reagent in the synthesis of the desired TiO2nano-particles.

Synthesis of TiO2 nanofiber for photocatalytic and antibacterial applications

Titanium dioxide (TiO2) nanofiber was successfully synthesized by electrospinning method. The synthesized TiO2 powder was characterized by using advanced techniques such as X-ray diffraction analysis (XRD) and Scanning electron microscope (SEM). The XRD pattern shows the formation of the anatase structure of synthesized TiO2 and the crystallite size was calculated using Debye-Scherer equation. SEM image shows the nanofibrous morphology of synthesized TiO2 nanomaterials. In the present work, the synthesized TiO2 nanofiber successfully decomposed the methylene blue dye under UV-light irradiation. The higher colour removal efficiency of 87.36% was achieved for the sample calcinated at 450 °C. Moreover, the antibacterial effect of the synthesized TiO2 nanofiber was screened by disc diffusion method using gram positive bacteria Bacillus cereus and gram negative bacteria Klebsiella pneumoniae. The maximum zone of inhibition (25 mm) in millimeter was observed by K. pneumoniae. Thus, concluded that they could act as promising materials for efficient photocatalytic rate and good antibacterial agent.

The role of fuel to oxidizer ratio in solution combustion synthesis of TiO2 and its influence on photocatalysis

Abstract

Tailoring luminescence properties of a sol–gel drivenTiO2 nanoparticles by ammonia treatment

Titanium dioxide (TiO2) nanopowders were prepared by the sol–gel process vie gelation at different pH values (6.8−12.5) in ammonia solution calcined at 500 °C for 2 h. The x-ray diffraction patterns showed that all samples exhibited a tetragonal anatase TiO2 phase. The crystallite sizes increases from 10 to 14 nm and band gap energy ranges from 3.2 and 3.3 eV as the solution pH is increased from 6.8 to 12.5. The lattice constants increased with increasing the synthesized pH value, which implies also a decrease of the micro-strain. The highest blue emission peak centered at around 416 nm was observed for the pH 12.5 compared with low pH values in the photoluminescence spectra of the synthesized TiO2 powders. Experimental results showed that TiO2 nanoparticles synthesized at pH 12.5 exhibited the optimal structural and luminescence properties.

Low Temperature Synthesis of High Energy Facets Exposed Sheet–like Anatase TiO2 Mesocrystals Show Reduced e−/h+ Pair Recombination Rates and Enhanced Photoactivity

AbstractHerein, we report low temperature synthesis of anatase TiO2 mesocrystals with {001} facets exposed sheet‐like morphology via fluorine‐free synthesis by the synergistic effect of microwave and ultrasound treatments. The synthesized TiO2 powder showed higher surface area and enhanced photocatalytic degradation of a model dye under white light irradiation. The sheet‐like anatase TiO2 mesocrystals resulted long‐lived charge carriers and separation that was confirmed from photoluminescence and photocurrent measurements. A five‐fold enhancement in the photocurrent was obtained for the mesocrystals compared to reference sample, which revealed that the orientation of nanocrystallites in sheet‐like morphology play a pivotal role in electron transport. The effect of charge carriers on photocatalytic activity was studied in detail and it followed the order, hydroxyl radicals&gt; holes&gt;electrons. Additionally, the TiO2 sol showed excellent stability. Further, the photoinactivation of Escherichia coli and Candida albicans was evaluated using zone of inhibition test under indoor irradiation and synthesized anatase TiO2 showed a clear zone of inhibition with diameter 37.2 mm and 40.0 mm, respectively whereas commercial TiO2 shows meager inactivation. The results indicate that our approach of combined microwave and sonication can serve as a facile approach for the synthesis of {001} facets exposed anatase sheet‐like TiO2 mesocrystals under halide‐free and low temperature conditions.

Anomalous behavior of visible light active TiO2 for the photocatalytic degradation of different Reactive dyes.

Nanocrystalline undoped, N-doped, N and metal codoped titania with different particle size, surface area, anatase phase content, crystallinity, band gap and zeta potential were synthesized by the sol-gel method. The photocatalytic activities of the synthesized TiO2 powders were compared by employing four different Reactive dyes. The order of photocatalytic activity observed for Reactive Red 198 dye (RR 198) was undoped = N,Cu codoped = N-doped > N,Fe codoped TiO2, Reactive Blue 4 dye (RB 4) was N,Cu codoped > N,Fe codoped > N-doped > undoped TiO2, Reactive Black 5 dye (RB 5) was N,Cu codoped* > undoped > N-doped > N,Fe codoped TiO2 and negligible degradation was observed for Reactive Orange 16 dye (RO 16). In this paper, the anomalous trend of the photocatalytic activity of various photocatalysts for the degradation of a particular class of dyes has been observed and accounted for based upon three parameters: mechanism of degradation, physicochemical properties of the catalyst and adsorption behavior based on the zeta potential. It was concluded that apart from these parameters, the substrate-specificity of the catalyst is also of equal importance in developing new catalysts for the photodegradation of dyes present in textile effluents.

Synthesis, characterization and photocatalytic properties of rod-shaped titanium dioxide

Rod-shaped titanium dioxide (TiO2) powder was successfully synthesized by simple inexpensive solution growth technique with and without the aid of biosurfactant-palmitic acid. The synthesized TiO2 powder was characterized using advanced techniques such as X-ray diffraction analysis, Scanning electron microscope (SEM) with Energy dispersive analysis, Fourier transform infra red spectroscopy (FT-IR), Photoluminescence and Micro Raman spectral studies. SEM observation of the synthesized TiO2 powder clearly shows rod-shaped particle formation which was influenced by palmitic acid. The Ti–O–Ti stretching band at 450–800 cm−1 was confirmed by FT-IR studies. The synthesized rod-shaped titanium dioxide strongly decomposes the Alizarin Red S dye under UV light irradiation. The maximum dye decolourization efficiency of 99.4 % was achieved by the addition of rod-shaped TiO2 powder.

Effect of initial water content and calcination temperature on photocatalytic properties of TiO2 nanopowders synthesized by the sol–gel process

The effects of initial water content and calcination temperature on sol–gel synthesized TiO2 powders were studied. Mother solutions had water/Ti-precursor mole ratios (R ratio) of 1, 5, 10, and 50. Dried aerogels were calcined for 3h at temperatures of 300, 400, and 500°C to obtain crystallized TiO2 nanopowders in the range of 15–30nm. FE-scanning electron microscopy and X-ray diffraction techniques were employed to investigate the morphological and structural properties of the nanopowders synthesized. Profound effect of gel viscosity was observed on the formation mechanism and extent of crystallinity in the powders. Methylene blue degradation test results suggest, photocatalytic performance is enhanced as initial water content and calcination temperature increased. Band-gap energy of the powders ranged from 3.09 to 3.27eV. Overall, this study shows that initial water content and calcination regime have a profound effect on the phase assembly, crystallite size, band-gap energy, and photocatalytic performance of sol–gel synthesized TiO2 nanopowders.

Structural characterization and optical property of TiO2 powders prepared by the sol–gel method

The structural characteristics and optical property of TiO2 powders with different phases are studied by various techniques in this paper. Butyl titanate and oxalic acid were used as Ti source and catalyst, respectively, for sol–gel synthesis of TiO2 powders. The synthesized products were characterized by X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, thermogravimetric analysis and photoluminescence techniques. X-ray diffraction patterns confirm TiO2 phase transformation from amorphous to anatase and rutile with the increase in calcination temperatures from 200°C to 700°C. Two exothermic peaks at 275°C and 485°C on the differential scanning calorimetry curve are responsible for the decomposition of the oxalate groups, which can enhance TiO2 phase transformation from amorphous to anatase and rutile. The crystalline sizes of the synthesized TiO2 powders are in the range of 20–65nm. The coherent phase boundary between (200) crystal plane of anatase and (11−2) crystal plane of rutile is determined first time, based on the Fourier transform analysis. The near band edge emission peaks of anatase at 396nm and rutile at 419nm, and four peaks of the different defects in TiO2 crystals can be identified on the photoluminescence spectra of the synthesized TiO2 powders. The activation energies for the grain growths of anatase and rutile were calculated, indicating that the surface chemistry may be a critical parameter to control grain growth. Based on the experimental results, the mechanism for the formation of anatase and rutile TiO2 is discussed.

Synthesis and physicochemical characteristics of titanium dioxide doped with selected metals

The paper details with of the preparation and physicochemical characterisation of nano- and microstructured TiO2 doped with Fe and Co produced by the sol-gel method using titanium alkoxide as the precursor of titania as well as iron or cobalt nitrates as dopant sources. Fe and Co doped TiO2 materials were successfully prepared with two different methods. The effect of the dopant type on the synthesis of TiO2 powders was investigated. The physicochemical properties of the studied samples were determined. The characterisation included determination of the dispersion and morphology of the systems (particle size distribution, SEM images), characteristics of porous structure (BET isotherms), crystalline structure (XRD), surface composition (EDS), as well as thermal stability (TG/DTA).

Photocatalytic efficiency of titania photocatalysts in saline waters

The photocatalytic efficiency of the recently synthesized TiO2 powder, named P160, of the degradation of dye Dye C.I. Reactive orange 16 in natural and artificial seawater was investigated in comparison to its efficiency in deionized water and the efficiency of a standard TiO2 powder Degusa P25. It was shown that the photocatalytic efficiency of P160 was slightly higher than that of P25, probably due to slightly higher specific surface area, higher pore volume and larger pores of the powder P160. The efficiency of both photocatalysts in natural and artificial seawater was significantly lower than that in deionized water. The overall rate of dye degradation for both types of photocatalysts is litle higher in artificial seawater than in natural seawater, which shows the influence of organic compounds naturally present in seawater on the photocatalysts activity. A saturation Langmuir-type relationship between the initial degradation rate and the initial dye concentration indicates that the adsorption plays a role in the photocatalytic reaction. The photodegradation rate constant k, which represents the maximum reaction rate, has similar values for P25 and P160 in all types of water due to the similar properties of the photocatalysts.