Anatase TiO2 Powder Research Articles

Synthesis of anatase powder by ilmenite digestion followed by selective thermal decomposition and leaching

This study investigates an innovative method for producing TiO2 from ilmenite ore through selective thermal decomposition and leaching. The focus lies on understanding the impact of co-existing sulfates on the decomposition temperature of TiOSO4. Insights into the decomposition mechanisms and parameters governing selective leaching efficiency are also presented. Ilmenite concentrate was digested with concentrated sulfuric acid, yielding titanium and iron sulfates. The digested cake was then calcined at different temperatures to induce thermal decomposition. Thermodynamic calculations were employed to model the decomposition reactions and investigate the influence of iron sulfates on TiOSO4 decomposition. Both thermodynamic evaluation and experimental results demonstrate that co-existing iron sulfates play a catalytic role in lowering the decomposition temperature of TiOSO4 from approximately 700°C to below 500°C, facilitating its conversion to TiO2. The calcined powder underwent selective leaching, first with water to remove soluble sulfates, followed by dilute acid to obtain a TiO2 precipitate. The precipitate was analyzed by different techniques.The XRD analysis confirmed the successful conversion of TiOSO4 to Anatase TiO2 during calcination and leaching. The SEM images show that the Anatase TiO2 powder displays a near-spherical morphology, with a particle size ranging from 50 to 200 nm. FTIR, DTA, and DTG analyses supported the thermodynamic calculations and XRD results, offering insights into the phase transformations during thermal decomposition and leaching. The thermodynamic evaluation and experimental results demonstrate that co-existing iron sulfates play a catalytic role in lowering the decomposition temperature of TiOSO4. By using the proposed method, anatase powder was successfully produced with minor impurities of iron, SiO2, and other metal oxides.

The Aqueous Aluminium-Ion Battery: Optimising the Electrode Compression Ratio through Image-Based Modelling

The aqueous Al-ion battery potentially has improved safety and environmental advantages over the incumbent lithium-ion technology [1,2]. Using 3D carbon-felt matrix electrodes, the performance of these batteries can be optimised. Typically, the electrodes are compressed to improve electrical conductivity by improving contact between adjacent fibres, which also closes the electrolyte pores, reducing the ionic diffusivity [3]. In this work, we set out to understand the role of electrode compression on the interplay between these key performance parameters for the aq. Al-ion battery.Synchrotron X-ray computed tomography was used to examine the 3D morphology of the carbon felt electrodes under 11 different compression ratios [4]. A bespoke in-situ tensile/compression rig was used to measure displacement and loading for three electrode types: raw carbon felt, positive electrodes loaded with a copper hexacyanoferrate ink and negative electrodes loaded with TiO2 anatase powder. Data was acquired using two voxel sizes (330nm, and 540nm) to compare the effects of spatial resolution and imaged volume size on subsequent image analysis. The tomograms were reconstructed using Paganin phase retrieval, to improve the contrast of the weakly attenuating carbon, and a filtered back projection algorithm. A U-net convolutional neural network was trained on uncompressed, fully compressed and partially compressed (three volumes) data, and then used to fully segment all tomograms.A high-throughput, image-based model was then used to analyse how compression affects the porosity, tortuosity, volume-specific area, ionic diffusivity, and electrical conduction of the electrodes. A finite differences-based model was used to solve the equilibrium partial differential equations directly on the voxel datasets, with no additional regularisation [5]. The heterogeneity of the electrode samples is quantified by comparing the effect of representative elementary volume on the value of the computed parameters [6]. Finally, aq. Al-ion batteries are manufactured using the predicted optimal compression ratio and compared to the simulated results.This is the first in-situ study of the compression effect on the aqueous aluminium-ion battery, and the largest XCT-based modelling study known to the authors (99 XCT tomograms). This work aims to improve the understanding of the effect of manufacturing parameters on the aqueous Al-ion battery and other similar batteries, and ultimately, its performance.[1] Melzack, N. "Advancing battery design based on environmental impacts using an aqueous Al-ion cell as a case study." Scientific Reports 12, no. 1 (2022): 8911.[2] Melzack, Nicole, R. G. A. Wills, and Andrew Cruden. "Cleaner energy storage: Cradle-to-gate life cycle assessment of aluminum-ion batteries with an aqueous electrolyte." Frontiers in Energy Research 9 (2021): 699919.[3] Mckerracher, R. D., A. Holland, A. Cruden, and R. G. A. Wills. "Comparison of carbon materials as cathodes for the aluminium-ion battery." Carbon 144 (2019): 333-341.[4] Reinhard, Christina, Michael Drakopoulos, Sharif I. Ahmed, Hans Deyhle, Andrew James, Christopher M. Charlesworth, Martin Burt et al. "Beamline K11 DIAD: A new instrument for dual imaging and diffraction at Diamond Light Source." Journal of Synchrotron Radiation 28, no. 6 (2021): 1985-1995.[5] Le Houx, James, and Denis Kramer. "Openimpala: Open source image based parallisable linear algebra solver." SoftwareX 15 (2021): 100729.[6] Le Houx, James, Siul Ruiz, Daniel McKay Fletcher, Sharif Ahmed, and Tiina Roose. "Statistical Effective Diffusivity Estimation in Porous Media Using an Integrated On-site Imaging Workflow for Synchrotron Users." Transport in Porous Media 150, no. 1 (2023): 71-88.

Facile Synthesis of Pre-Lithiated LiTiO2 Nanoparticles for Quick Charge and Long Lifespan Anode in Lithium-Ion Batteries.

Titanium dioxide (TiO2) has been widely used as an alternative anodic material for lithium-ion batteries (LIBs) due to its ultrahigh capacity retention and long cycle lifespan. However, the restriction of lithium insertion, intrinsically poor electronic conductivity, and sluggish lithium ionic kinetics of bulk TiO2 hinder their specific capacity and rate performance. Herein, LiTiO2 nanoparticles (NPs) are synthesized via a facile ball milling method by the reaction of anatase TiO2 with LiH. The as-prepared LiTiO2 NPs have strong structural stability and a "zero strain" effect during the repeated intercalation/deintercalation, even at low potential. As anodic materials for LIBs, LiTiO2 NPs exhibit a superior rate performance of ∼100 mA h g-1 at 10C (3350 mA g-1) with a capacity retention of 100% after 1000 cycles, which is 5 times higher than that of the original commercial anatase TiO2 powder. The higher specific capacity of LiTiO2 NPs is attributed to the increased conversion of Ti3+ to Ti2+ on the porous surface of LiTiO2 NPs, which provides a more capacitive contribution. This study not only provides a new fabrication approach toward Ti-based anodes for ultrafast LIBs but also underscores the potential importance of embedding lithium into transition metal oxides as a strategy for boosting their electrochemical performance.

Hydrogenation shrinks the colossal permittivity of Sb/Co co-doped TiO2 nanoparticles-structural and optical investigations

Pristine and (Sb/Co)-codoped TiO2 anatase powders were synthesized by hydrothermal method and some of the samples were hydrogenated. The samples were characterized by the traditional techniques: X-rays, optical diffuse reflection spectroscopy (DRS), and ac-electrical measurements. It was observed that the (Sb/Co) codoping induces the growth of the anatase. The optical absorption investigation was clarified by the generation of an intermediate band in the bandgap of TiO2. The catalysis power of the Co2+ ions to the adsorbed H2-dissociation strongly supports the optical absorption strength. The Sb5+/Co2+ codoping could generate weak colossal permittivity, which was lowered by ∼50% with hydrogenation. Such important results was studied and explained.

Photoactivity Enhancement of TiO2 Nanoparticle-decorated ZnO as a Photocatalyst in Methylene Blue Degradation

Zinc Oxide (ZnO) and Titanium Dioxide (TiO2) are metal oxides that are commonly used as photocatalysts material due to photoactivity characteristics. ZnO has a better reduction potential, and high electron mobility, but has a lower contact surface area than TiO2. On the other side, TiO2 has a better photoactivity to degrade pollutants referring to high surface area but has lower electron mobility compared to that ZnO. The combination of these two metal oxides is estimated can produce a better photocatalytic activity due to the advantages of each characteristic. Therefore, in this research, the ZnO-TiO2 (1:1) was prepared and investigated. ZnO nanoparticle was synthesized by the sol-gel method using zinc acetate dihydrate as a precursor, before calcining process, anatase TiO2 powder was added to form the composite. Structural, morphological, and optical characteristics of composite powders were analyzed by using XRD, TEM, UV-Vis Spectroscopy, and PL Spectroscopy. The concentration degradation of methylene blue in a solution containing composite material was observed to determine the photocatalytic activity under UV light irradiation for 30 minutes. The XRD spectrum shows the anatase phase of TiO2 and hexagonal wurtzite of ZnO crystal structure. Based on TEM imaging ZnO nanoparticles were attaching to TiO2 surfaces estimated due to van der walls bond. The ZnO/TiO2 shows a better photoactivity up to 20 minutes reaction with a higher degradation constant rate that indicates faster methylene blue degradation.

Plasma–induced rapid crystallization and surface engraving of amorphous TiOx(OH)y to enhance adsorption and photocatalytic activity

Herein, we highlight a facile, green, and controlled technique commonly known as plasma-liquid interaction for crystal growth, defect engineering, and surface modification of amorphous titanium oxide. Using a novel two-step procedure combining hydrolysis and plasma treatment, we have fabricated defect-enriched anatase TiO2 powder. Rapid crystallization of amorphous titanium oxide is observed due to the interaction of plasma-generated reactive species with the solvated material. However, prolonged treatment time decreases the material's crystallinity due to excess generation of oxygen vacancy defects (OVD) in the TiO2 lattice. The plasma treatment also engraves the material’s surface forming the porous structure, increasing the specific surface area to ∼46 %. At a higher treatment time, TiO2 nanoparticles are grown on the material’s surface. The dye adsorption of the material is quite rapid, and the performance depends on the material’s surface condition. This rapid adsorption speeds up the photo-degradation performance (up to ∼96 %) of the material. The presence of OVD increases the photocatalytic activity of the material. However, an excess amount of OVD quenches the activity. A comparative study between ambient air and argon plasma-assisted material modification for optimized adsorption and photocatalytic performance has been carried out.

Grain growth and phase transformation of nano-sized titanium dioxide powder during heat treatment and spark plasma sintering

The control of nanostructures is crucial for enhancing the thermoelectric properties of materials. In this work, the grain growth and phase transformation of different nano-sized titanium dioxide (TiO2) powders were investigated during heat treatment and spark plasma sintering. First, the thermal behaviors of TiO2 powders with different particle sizes during heat treatment, such as grain growth, phase transformation, and adsorption properties, were studied. The results showed that the phase transformation of 7 nm anatase TiO2 occurred more easily, and the rutile phase content increased with increasing heat treatment temperature. The grain growth of 7 nm anatase TiO2 occurred at low temperature (i.e., 873 K), even the grain size increased by 13-fold at 1123 K (i.e., the phase transformation temperature). Thermogravimetry results suggested that the 7 nm anatase TiO2 powder had a greater adsorption characteristic owing to its large specific surface area. Moreover, TiO2 compacts with and without graphite were fabricated using spark plasma sintering. The results indicated that a lower sintering temperature was beneficial for maintaining the nanostructure, whereas the addition of graphite powder promoted grain growth. Furthermore, the thermal conductivity was reduced owing to the nanostructure, and the phonon thermal conductivity accounted for a dominant proportion of the total thermal conductivity. Consequently, the lowest thermal conductivity was 1.1 Wm−1K−1 at 973 K for the nanostructured compact sintered at 1073 K, which is approximately 50% lower than that of the microstructured compact sintered at 1273 K.

Spectral dependence of UV light penetration into powder TiO2 anatase

The penetration depth of UV monochromatic light into deposited TiO2 anatase powder was investigated. The light penetration depth was considered in units of numbers of surface hole, Ns, and electron, NO2, centers activated during irradiation. The numbers of hole centers Ns were obtained from photostimulated oxygen isotope exchange reaction registered by means of mass spectrometry. The numbers of electron centers NO2 were obtained from subsequent thermo-programmed desorption spectroscopy of photoadsorbed oxygen O2-. It was shown that the depth D of UV light penetration into UV absorbing TiO2 powder coat depends on the wavelength and intensity I0 of incident UV light and obeys to the equation DI0=1kefflg(I0/Im) obtained from the Beer–Lambert–Bouguer law with effective extinction coefficient keff and minimal value of light intensity Im, below which the photoactivation is considered negligible. Commonly, the value Im has an order of a few microwatts/cm2 for activation of electron and hole type centers except for a case of 334 nm falling into the band of the first direct band-to-band transition of anatase, where relatively high threshold value Im=0.063 mW/cm2 for photoactivation of hole centers was revealed. Effective extinction coefficient keff may be considered proportional to the absorption coefficient of TiO2 in the region of fundamental absorption, whereas, in the non-fundamental absorption region, keff exceeds significantly that of TiO2 due to, probably, dominating scattering processes. At small intensities of the incident light, there is a strong sensitivity of the penetration depth (and activated surface) to the intensity.

A Simple Method for Low-temperature Sintering of Titania

A low-temperature sintering process was used to produce pellets at different temperatures using TiO2 anatase (Vetec) and P25 (Evonik) commercial powders. The initial powder was mixed with 75% acetic acid aqueous solution and pressed under 375 MPa. The temperature was applied after the pelletization in a conventional furnace for 4 hours. The best sintering temperature for anatase was 800°C, which is higher than typical cold sintering temperatures but below conventional ones. However, the optimal temperature was 450 °C for P25 due to its density and SEM results. The sintered pellets' maximum densities were 70% (anatase, 800oC) and 66% (P25, 450oC). It was not possible to measure the anatase pellets treated under 800oC because they disintegrated in water. This work studied the effects of the applied pressure, solvent concentration, particle size, and sintering temperature on the properties of sintered pellets, such as integrity, density, and presence of porous. It also evaluated the electrochemical activity measured by cyclic voltammetry (CV), which indicated that the sintered TiO2 pellets are porous with a partial capacitive response.

Effect of a long-term exposure of anatase TiO2 powder doped with surface-located Sb3+ ions to UV radiation on its photocatalytic activity

Ultraviolet photocatalytic experiments on the kinetics of decolorization of methyl orange and the 121Sb Mössbauer characterization of the title catalyst were performed. The stereochemically active electronic lone pair of Sb3+ was found to completely deactivate the neighboring oxygen vacancy as a recombination center towards the photogenerated electrons and holes.

In Situ Investigation of Charge Performance in Anatase TiO2 Powder for Methane Conversion by Vis-NIR Spectroscopy.

The intrinsic behavior of photogenerated charges and reactions with chemicals are key for a photocatalytic process. To observe these basic steps is of great importance. Here we present a reliable and robust system to monitor these basic steps in powder photocatalysts, and more importantly to elucidate the key issue in photocatalytic methane conversion over the benchmark catalyst TiO2. Under constant excitation, the absorption signal across the NIR region was demonstrated to be dominated by photoexcited electrons, the absorption of photoexcited holes increases toward shorter wavelengths in the visible region, and the overall shapes of the photoinduced absorption spectra obtained using the system demonstrated in the present work are consistent with widely accepted transient absorption results. Next, in situ measurements provide direct experimental evidence that the initial step of methane activation over TiO2 involves oxidation by photoexcited holes. It is calculated that 90 ± 6% of photoexcited electrons are scavenged by O2 (in dry air), 61 ± 9% of photoexcited holes are scavenged by methane (10% in argon), and a similar amount of photoexcited electrons can be scavenged by O2 even when the O2 concentration is reduced by a factor of 10. The present results suggest that O2 is much more easily activated in comparison to methane over anatase TiO2, which rationalizes the much higher methane/O2 ratio frequently used in practice in comparison to that required stoichiometrically for photocatalytic production of value-added chemicals via methane oxidation with oxygen. In addition, methanol (a preferable product of methane oxidation) is much more readily oxidized than methane over anatase TiO2.

Binding of collagen gene products with titanium oxide.

Titanium is the only metal to which osteoblasts can adhere and on which they can grow and form bone tissue in vivo, resulting in a strong bond between the implant and living bone. This discovery provides the basis for the universal medical application of Ti. However, the biochemical mechanism of bond formation is still unknown. We aimed to elucidate the mechanism of bond formation between collagen, which constitutes the main organic component of bone, and TiO2, of which the entire surface of pure Ti is composed. We analysed the binding between the soluble collagen and TiO2 by chromatography with a column packed with Ti beads of 45 µm, and we explored the association between collagen fibrils and TiO2 (anatase) powders of 0.2 µm. We ran the column of chromatography under various elution conditions. We demonstrated that there is a unique binding affinity between Ti and collagen. This binding capacity was not changed even in the presence of the dissociative solvent 2M urea, but it decreased after heat denaturation of collagen, suggesting the contribution of the triple-helical structure. We propose a possible role of periodically occurring polar amino acids and the collagen molecules in the binding with TiO2.

Kinetic Studies of Methylene Blue Degradation using CaTiO3 Photocatalyst from Chicken Eggshells

This study details the kinetic of photodegradation of methylene blue in aqueous medium using CaTiO3 photocatalyst. The CaTiO3 catalyst was prepared by sol-gel reaction using CaCO3 derived from chicken eggshell and anatase TiO2 powder. The CaTiO3 particles were prepared using a mixture of starting materials in of (1:1); (1:3); (2:5) and (2:7) CaCO3/TiO2 molar ratio at T = 900°C. The physical and microstructural properties of CaTiO3 microstructural were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), Fourier Transform Infrared (FTIR) and UV/vis spectrometer. As prepared CaTiO3 particles with various composition of CaCO3/TiO2 were then applied for removal of dye molecules under simulated UV irradiation. The effect of initial dye concentration, catalyst composition, and degradation time on the adsorption property of CaTiO3 was systematically investigated. The results reveal that methylene blue (MB) molecules are efficiently adsorbed and degraded within 120 min using CaTiO3 catalysts. Considering the low-cost preparation process and considerably high photocatalytic performance obtained in this work, CaTiO3 can further be used as an efficient photocatalyst for organic pollutant removal from industrial wastewater.

Preparation of Anatase Titanium Dioxide Nanoparticle Powders Submitting Reactive Oxygen Species (ROS) under Dark Conditions

Recently, under the circumstances of pandemic of COVID-19 much attention has been paid to titanium dioxide TiO2 as bactericidal agent; however, conventional TiO2 requires ultraviolet radiation or visible light to exercise its photocatalytic properties and its induced antimicrobial activity. In order to expand its applications directed at wide civil life, antibacterial TiO2 being usable under dark conditions has been demanded. The present paper describes the powder characterization of newly developed potassium K and phosphorous P co-doped nanometer-size anatase TiO2 powders using X-ray diffraction (XRD), scanning and transmission electron microscopies (SEM & TEM), Brunauer-Emmett-Teller method (BET), fourier-transform infrared spectroscopy (FT-IR), X-ray absorption fine structure (XAFS), electron spin resonance (ESR) and chemiluminescence (CL). It was found for the first time that thus prepared anatase TiO2 could submit much reactive oxygen species (ROS) even in the dark, which has close relation with bactericidal activity in light interception.

Enhanced visible light photocatalytic activity of Fe2O3 modified TiO2 prepared by atomic layer deposition

In this work, commercial anatase TiO2 powders were modified using ultrathin Fe2O3 layer by atomic layer deposition (ALD). The ultrathin Fe2O3 coating having small bandgap of 2.20 eV can increase the visible light absorption of TiO2 supports, at the meantime, Fe2O3/TiO2 heterojunction can effectively improve the lifetime of photogenerated electron–hole pairs. Results of ALD Fe2O3 modified TiO2 catalyst, therefore, showed great visible light driven catalytic degradation of methyl orange compared to pristine TiO2. A 400 cycles of ALD Fe2O3 (~ 2.6 nm) coated TiO2 powders exhibit the highest degradation efficiency of 97.4% in 90 min, much higher than pristine TiO2 powders of only 12.5%. Moreover, an ultrathin ALD Al2O3 (~ 2 nm) was able to improve the stability of Fe2O3-TiO2 catalyst. These results demonstrate that ALD surface modification with ultrathin coating is an extremely powerful route for the applications in constructing efficient and stable photocatalysts.

Carbon-containing-titania coated stainless steel prepared by high voltage powder spray coating and its adhesion phenomena

Nowadays, many studies involve coating materials on stainless steel prepared by various methods, and many approaches have been taken to improve the abrasion resistance of the coatings. Here, the attachment of carbon/titania (C/TiO2) on stainless steel and the evaluation of its coating adhesion is reported. The commercially available epoxy resin was used as the source of carbon, and the transformation from epoxy resin to pyrolytic carbon was performed. It is proposed that the incorporation of an inorganic particle will improve the adhesion properties through the reduction of the carbon shrinkage. C/TiO2 was prepared from the mixture of commercialized epoxy resin (Oxyplast PR12®) and anatase TiO2 powder, followed by spraying the mixture onto stainless steel (AISI 304) surface using high voltage powder spray coating (HVPSC). The sprayed powders on stainless steel underwent pyrolysis at several temperatures from 300 to 700 °C for an hour to determine the optimum temperature for excellent adhesion. The physical properties of C/TiO2 coated samples were characterized by Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), surface profiler meter and X-ray photoelectron (XPS) spectroscopy. The FTIR analysis of C/TiO2 coating identified the appearance of peaks CH sp3, CO, CO, and TiO. It was noticed that the absorption band of CH sp3, CO, and CO slowly disappeared as the pyrolysis temperature increased, indicating that the structure changed from epoxide to pyrolytic carbon. FESEM images showed that the TiO2 particles were fully covered with the carbon layer, and the thickness was determined to be in the range of 4.8–15.5 μm. The abrasive and peel adhesion test was performed, showing no detachment of coated material of C/TiO2 pyrolyzed at 300 °C, suggesting that this temperature produces the best coating adhesion. The carbon-based coating adhesion phenomena were elucidated by XPS analysis of Fe2p, C1s, and Ti2p element peaks. It was demonstrated that the presence of an oxide layer on stainless steel, availability of functional groups, and structure shrinkage were the factors that affect the adhesion of the carbonaceous coating. The structure shrinkage was reduced due to the presence of TiO2, which is associated with strong coating adhesion. This demonstrated that the carbonaceous coating produced by HVPSC formed an excellent adhesion in the presence of TiO2.

Low temperature synthesis of anatase TiO2 nanocrystals using an organic-inorganic gel precursor

The purpose of this research was to establish a novel approach to synthesize nano-crystalline anatase TiO2 powder through a low temperature solution process and extracting TiO2 from the solution via freeze-drying procedure. The amorphous TiO2 precursors were first prepared using an aqueous TiCl4 solution and N, N-dimethylformamide as a TiO2 structure directing agent at 40 °C. The freeze-drying treatment of the DMF-derived amorphous Ti(IV) gel precursors produced organic–inorganic hybrids, including crystallized tiny TiO2 particles. The size, shape, and crystal phase of the TiO2 particles were determined by using transmission electron microscopy and X-ray diffraction. Most notably, anatase TiO2 nanocrystals were successfully obtained at less than near-room temperature. Furthermore, a sintering process of the gel precursors at 500 °C produced anatase TiO2 nanoparticles with three-dimensional network morphology. The resulting nanoparticles were found to have approximate grain sizes of 30–50 nm, with the organic-inorganic gel supporting the crystallization as a template.

The Effects of Synthesis Conditions on the Carbon Capture Capacity of Polyethylenimine Impregnated Protonated Titanate Nanotubes

Capture and storage of carbon dioxide emitted from power plants, which burn fossil fuels, is one of the best ways to mitigate climate change. Polyethylenimine (PEI) impregnated protonated titanate nanotubes (PEI-PTNTs) are efficient amine-modified solid adsorbents for post combustion carbon capture. This study is to investigate the effects of synthesis conditions of titanate nanotubes on the carbon capture capacity of PEI-PTNTs. PTNTs are synthesized using hydrothermal treatment of TiO2 anatase powder at different temperatures and in different days, followed by washing with dilute HCl solution and deionized water. PEI-PTNTs are prepared by loading PEI (M.W. = 10,000) onto PTNTs at a weight ratio of 1:1 using a wet impregnation process. PTNTs and PEI-PTNTs are characterized using transmission electron microscopy, porosity and surface area analysis, powder X-ray diffraction, and Fourier transform infrared spectroscopy. CO2 adsorption is conducted at 75 °C using simulated flue gas, and CO2 desorption is performed at 110 °C by purging the adsorbent with dry nitrogen gas. CO2 adsorption experiments demonstrate that the PEI-PTNTs synthesized at 130 °C within 3 or 5 days, have the highest CO2 capture capacity. These optimized PEI-PTNTs have a significant potential to capture CO2 from power plants.

Anatase TiO2 powder immobilized on reticulated Al2O3 ceramics as a photocatalyst for degradation of RO16 azo dye

The three-dimensional network of open-celled Al2O3 ceramic supports were first fabricated using a polymeric sponge replication technique. The polyurethane foams soaked with the highly loaded Al2O3 ceramic slurry were drained, slowly dried and sintered at 950 °C to complete the burn out process and to construct the ceramic preforms. They were then carefully soaked again with the moderately loaded Al2O3 slurry and sintered at 1500 °C to increase their strength. Finally, the photocatalyst ceramic powder covering the outer surfaces was placed layer by layer through dipping the rigid Al2O3 supports repeatedly in the slurry of TiO2 powder. The dip-applied TiO2 was sintered eventually at relatively low temperature of 700 °C to prevent phase transformation. The efficiencies of the TiO2 coated Al2O3 samples were evaluated by the photocatalytic degradation of reactive orange 16 (RO16) azo dye molecules dissolved in water. Nearly complete color removals were achieved within 75 min under UVC irradiation.

Methyl Orange Degradation using TiO2 Powder and Immobilized TiO2 Photocatalysts

Methyl orange is one of the anionic dyes and is a major pollutant from textile industry that enters both aquatic and atmospheric systems. In this research, methyl orange was degraded using TiO2 powder and immobilized TiO2 on glass. Titanium tetra-isopropoxide (TTIP) was used for preparation of TiO2 powder using soft chemistry method, and it was immobilized on glass via paste-gel coating method. The prepared photocatalysts were characterized by XRD and SEM. Highly crystalline anatase TiO2 powder photocatalyst was obtained. Meanwhile, immobilized TiO2 was less crystalline and agglomerated onto the glass surface. TiO2 powder had higher degradation rate (71%) compared to immobilized TiO2 (52%) due to its chemical stability and larger amount of photocatalyst contacted with methyl orange during the degradation process.