Search Results (22)

The recovery and control of volatile organic compounds (VOCs) have gained significant attention. Supported sulfonic acid materials show potential in converting aromatic VOCs into non-volatile sulfonic acid derivatives. However, their effectiveness is closely tied to the anchoring state of the sulfonic acid groups. In this study, two supported sulfonic acids, SSA@CdO and SSA@CaO, were synthesized via the respective reactions of CdO and CaO with chlorosulfonic acid to investigate how the properties of the supports influence sulfonic acid anchoring and reactivity toward o-xylene. Comprehensive characterization and performance tests revealed that sulfonic acid groups on CdO were covalently bonded, forming positively charged sites ([O_0.5Cd–O]^ɗ−–SO₃H^ɗ+) with high loading (9.7 mmol/g), enabling excellent o-xylene removal (≥95.6%) and adsorption capacity (51.67–91.59 mg/g) at 130–150 °C. In contrast, ion-paired bonding on CaO formed negatively charged sites ([O_0.5Ca]⁺:OSO₃H⁻), which were inactive in electrophilic sulfonation. This work provides new insights for enhancing supported sulfonic acid materials in VOC treatment. Full article

Herein, all components of corncob residues were acetylated to synthesize an acetone-soluble resin material. Moreover, titanium oxysulfate (TiOSO₄), a low-cost intermediate for the industrial production of TiO₂, was first used as an acetylation reagent. Through optimizing reagent dosages and reaction times, above 90% of hydroxyl groups in the corncob residue can be substituted by acetyl groups. During the acetylation reaction, TiOSO₄ was transformed into TiO₂ and uniformly distributed within the acetylated corncob residue. The resulting product, owing to its solubility in acetone, can be employed to fabricate a composite film with excellent mechanical properties, achieving an increase of 85% in tensile strength and 90% in strain rate compared to commercial cellulose acetate film. By this preparation technique, the industrial-grade corncob residue as raw material can be converted to acetylated composite films. Further analysis indicates that the coexistence of acetylated lignin and TiO₂ plays a pivotal role in enhancing the mechanical properties of acetylated corncob residue composite film. Additionally, this material exhibits substantial degradation within 28 days under natural environmental conditions, whereas commercial cellulose acetate shows no significant changes even after 60 days. The present achievements are a significant breakthrough in the high-value technologies for the conversion of corncob residues. Full article

Recently, aquatic life and human health are seriously threatened by the release of pharmaceutical drugs. For a sustainable ecosystem, emerging contaminants like antibiotics must be removed from drinking water and wastewater. To address this issue pure and cerium-doped titanium dioxide (CeT) nanoparticles were produced with stable tetragonal (anatase) lattices by room temperature sol–gel method and employing the inorganic titanium oxysulfate (TiOSO₄) as titanium precursor. The structural analysis by X-ray diffraction (XRD) revealed that at calcination temperature of 600 °C all (un and doped) powders were composed of crystalline anatase TiO₂ with the crystallite sizes in the range of 13.5–11.3 nm. UV–vis DRS spectroscopy revealed that the most narrowed bandgap value of 2.75 eV was calculated for the 0.5CeT sample containing the optimum dopant content of 0.5 weight ratio. X-ray spectroscopy (XPS) confirmed the presence of the impurity level Ce³⁺/Ce⁴⁺, which became responsible for the decrease in bandgap as well as for the photoinduced carriers recombination rate. Photocatalytic tests showed that the maximum decomposition of the model spiramycin (SPR) antibiotic pollutant was 88.0% and 77.0%, under UV and visible light, respectively. According to the reaction kinetics, SPR decomposition adhered to the Langmuir–Hinshelwood (L–H) model and via ROS experiments mainly hydroxyl radicals (OH^•) followed by photogenerated holes (h⁺s) become responsible for the pollutant degradation. In summary, this study elaborates on the role of xCeT nanoparticles as an efficient photocatalyst for the elimination of organic contaminants in wastewater. Full article

The sol-gel process was used to create titanium dioxide (TiO₂) nanoparticles, a nanocrystalline semiconductor. How several synthesis factors, such as titanium precursor concentration, annealing temperature, and peptization temperature, affected the structural and morphological properties of TiO₂ nanoparticles were thoroughly explored. X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), measurements of the specific surface area and pore size using the BET method, and UV-visible diffuse reflectance spectroscopy were all used in this investigation. The specific surface area determined by BET analysis decreased with increasing calcination temperature. The XRD analysis showed that a composite sample consisting mainly of anatase with minor brookite phases was obtained when the titanium precursor concentration ranged between 0.2 and 0.4 M, whereas a concentration of 0.5 M resulted in the formation of pure anatase. The photocatalytic activity of the synthesized TiO₂ powders under different operational parameters was evaluated for the common commercial textile dye, i.e., methylene blue (MB). It was experimented that the model pollutant decoloration follows the Langmuir–Hinshelwood (L-H) model. In view of this detailed research work, it was observed that the TiO₂ produced with a titanium precursor concentration of 0.3 M, a pH value of 5 during the peptization step, and an annealing temperature of 600 °C were found to be the best conditions for this catalytic degradation process. When used in conjunction with a TiO₂ concentration of 0.04 g/L and a reactor suspension pH value of 6.0, the TiO₂ catalyst produced a stunning 98% degradation of methylene blue under these circumstances. Full article

Preparing high-performance oxygen evolution reaction (OER) catalysts with low precious metal loadings for water electrolysis applications (e.g., for green hydrogen production) is challenging and requires electrically conductive, high-surface-area, and stable support materials. Combining the properties of stable TiO₂ with those of active iridium oxide, we synthesized highly active electrodes for OER in acidic media. TiO₂ powders (both commercially available Degussa P-25^® and hydrothermally prepared in the laboratory from TiOSO₄, either as received/prepared or following ammonolysis to be converted to titania black), were decorated with IrO₂ by UV photodeposition from Ir(III) aqueous solutions of varied methanol scavenger concentrations. TEM, EDS, FESEM, XPS, and XRD measurements demonstrate that the optimized version of the photodeposition preparation method (i.e., with no added methanol) leads to direct deposition of well-dispersed IrO₂ nanoparticles. The electroactive surface area and electrocatalytic performance towards OER of these catalysts have been evaluated by cyclic voltammetry (CV), Linear Sweep Voltammetry (LSV), and Electrochemical Impedance Spectroscopy (EIS) in 0.1 M HClO₄ solutions. All TiO₂-based catalysts exhibited better mass-specific (as well as intrinsic) OER activity than commercial unsupported IrO₂, with the best of them (IrO₂ on Degussa P-25^® ΤiO₂ and laboratory-made TiO₂ black) showing 100 mAmg_Ir⁻¹ at an overpotential of η = 243 mV. Chronoamperometry (CA) experiments also proved good medium-term stability of the optimum IrO₂/TiO₂ electrodes during OER. Full article

Ti-bearing blast furnace slag (TBFS) can be converted to impurity bearing TiOSO₄ solution for TiO₂ pigment production. However, the H₂TiO₃ (MTA) hydrolyzed from the solution has too high Fe/V impurity to meet the standard for TiO₂ pigment. In this study, we found that Fe³⁺ and V³⁺ were easily hydrolyzed and entered the MTA lattice, and hence could not be removed by washing. Furthermore, Fe/V was hard to co-remove by the traditional reduction method. Therefore, the Fe/V non-hydrolysis condition (Ti³⁺ = 0.01 M, F = 3.0, T = 130 °C; Ti³⁺ = 0.01 M, F = 3.5, T = 150 °C) was determined by thermodynamic calculations. However, at these conditions, the Ti hydrolysis ratio was low or the reaction time was long. Therefore, a new two-step hydrothermal hydrolysis process was proposed. Step 1 (130 °C, 2 h) ensured the non-hydrolysis of V³⁺, and Ti was partially hydrolyzed to increase the H₂SO₄ concentration. Step 2 (150 °C, 2 h) ensured a high Ti hydrolysis ratio (>0.95) and short total reaction time (4–6 h). Finally, a high-purity MTA was obtained (Fe = 21 ppm, V = 145 ppm). These results provide new insights into the control of the hydrolysis of impurity ions in solutions and help to optimize the process of TiO₂ pigment preparation from TBFS. Full article

Titanosilicates comprise a broad class of materials with promising technological applications. The typical obstacle that restricts their industrial applicability is the high manufacturing cost due to the use of specific organotitanium precursors. We herein report a new approach to the synthesis of titanosilicates using an inexpensive inorganic precursor, ammonium titanyl sulfate (ATS or STA), (NH₄)₂TiO(SO₄)₂∙H₂O. The latter is an intermediate in the processing of titanium-bearing concentrates produced from apatite-nepheline ores. In this paper, the new synthetic approach is exemplified by the microwave-assisted synthesis of IONSIVE-911, one of the most effective Cs-ion scavengers. The method can be modified to synthesize various titanosilicate compounds. Full article

Ensuring uniform particle size distribution is a crucial role in the precipitation process of manufacturing white pigment. This study presents a comprehensive investigation that combines multiphase computational fluid dynamics (CFD) simulations with experimental research to effectively address the challenge of achieving uniform particle distribution during TiO₂ precipitation. The objective of this study was to enhance three-phase CFD simulations involving the mixing process of TIOSO₄ solution, steam as a gas phase, and solid seed particles. By analyzing the trajectories of the seed particles using CFD, the optimal injection position for the seed particles within the mixing process was determined. Subsequently, a lab scale test and real field test were conducted based on the insights gained from the CFD simulations. The particle size distribution of two different types of seed inlets was analyzed and compared using Transmission Electron Microscopy (TEM) and Scanning Electron Microscope (SEM). The findings of this study demonstrate that the developed multiphase CFD simulation can effectively enhance the precipitation process for the production of anatase titanium dioxide particles. Additionally, using the developed multiphase CFD solver, the real physics involved in the precipitation process were identified, leading to a better understanding of the process itself. Furthermore, TiO₂ particles with uniform particle size had a positive impact on the washing and bleaching processes following the precipitation process, resulting in a significant reduction in the annual defect production rate. Full article

The hydrolysis of an industrial titanyl sulfate (TiOSO₄) solution to metatitanic acid (H₂TiO₃) is the crucial step in the production of titanium dioxide (TiO₂) using the sulfuric acid process, and the extra-adding seeded route is generally adopted in industry, in which the quality of the crystal seeds plays a critical role. In this study, the optimal process conditions for preparing the crystal seeds via the NaOH neutralization method were first investigated. Then, the ultrasound-assisted preparation of crystal seeds was studied to explore the effect of the ultrasonic time and intensity on the particle size and particle size distribution of crystal seeds. The results demonstrated that ultrasonic assistance is helpful in obtaining crystal seeds with smaller particle sizes and more uniform particle size distribution, and the quality of the hydrolysis product of H₂TiO₃, i.e., the particle size and its distribution, is strictly correlated with those of the crystal seeds. Under the optimal process conditions for preparing the hydrolytic seeds, the average particle of the hydrolytic seeds prepared without ultrasonic assistance is 25.50 nm. In contrast, the introduction of ultrasonic assistance in the preservation stage could significantly decrease the particle size and narrow the particle size distribution of the hydrolytic seeds. When the ultrasonic time is 4 min and the ultrasonic intensity is 40 W, the average particle of the hydrolytic seeds is decreased to 23.48 nm. Therefore, the quality of the crystal seeds, as well as that of H₂TiO₃ products, could be significantly improved by introducing ultrasonic assistance with a suitable intensity at a suitable time in the preparation process of crystal seeds via the NaOH neutralization method. Full article

As the byproduct in the smelting process of vanadium titano-magnetite, titanium-bearing blast furnace slag (TBFS) can be converted to a titanyl sulfate (TiOSO₄) solution containing MgSO₄ and Al₂(SO₄)₃ impurities via dissociation by concentrated H₂SO₄ (80–95%) at 80–200 °C, followed by leaching with H₂O at 60–85 °C. In this study, hydrated TiO₂ was prepared by hydrothermal hydrolysis of a Mg/Al-bearing TiOSO₄ solution at 120 °C and the hydrolysis law was investigated. The experimental results indicate that MgSO₄ and Al₂(SO₄)₃ accelerated the hydrolysis and significantly affected the particle size (increasing the primary agglomerate size from 40 to 140 nm) and dispersion (reducing the aggregate size from 12.4 to 1.5 μm) of hydrated TiO₂. A thermodynamic equilibrium calculation showed TiOSO₄ existed as TiO²⁺ and SO₄²⁻ in the solution, and MgSO₄ and Al₂(SO₄)₃ led to little change of [TiO²⁺], but an obvious decrease of [H⁺], which favored the hydrolysis process. At the same time, the coordination–dissociation mechanism of SO₄²⁻ and Al(SO₄)₂⁻ facilitated the lap bonding of Ti-O-Ti, promoting the growth of hydrated TiO₂ synergistically. Full article

This paper describes the chemical engineering aspects for the preparation of highly active and stable nanocomposite photocatalysts based on N-doped TiO₂. The synthesis is performed using titanium oxysulfate as a low-cost inorganic precursor and ammonia as a precipitating agent, as well as a source of nitrogen. Mixing the reagents under a control of pH leads to an amorphous titanium oxide hydrate, which can be further successfully converted to nanocrystalline anatase TiO₂ through calcination in air at an increased temperature. The as-prepared N-doped TiO₂ provides the complete oxidation of volatile organic compounds both under UV and visible light, and the action spectrum of N-doped TiO₂ correlates to its absorption spectrum. The key role of paramagnetic nitrogen species in the absorption of visible light and in the visible-light-activity of N-doped TiO₂ is shown using the EPR technique. Surface modification of N-doped TiO₂ with copper species prevents its intense deactivation under highly powerful radiation and results in a nanocomposite photocatalyst with enhanced activity and stability. The photocatalysts prepared under different conditions are discussed regarding the effects of their characteristics on photocatalytic activity under UV and visible light. Full article

In this paper, a universal technology is proposed for processing low-titanium mineral raw material—apatite-nepheline ore waste, including its treatment with sulfuric or hydrochloric acid in a two-stage mode with a sequential increase in the concentration. This technique allowed us to remove nepheline and apatite in the first stage and achieve a titanium mineral content of TiO₂ of more than 30%; in the second stage, we were able to convert the titanium into its precursors—titanyl sulfate monohydrate TiOSO₄·H₂O and a hybrid rutile-silica composition. The key stage in the sorbent synthesis is the reaction of the precursor with a phosphoric acid solution. The preferred sequence of operations begins with the mechanical activation of the precursor, causing morphological changes in it, and subsequent treatment with phosphoric acid at different concentrations under atmospheric conditions and in an autoclave, accompanied by phase transformations. Conditions for the chemical reactions which regulated the composition and structure of the final product and, accordingly, its sorption activity were found. With the help of XFA, the phase compositions of the sorbents were identified, including the individual crystalline phase α-TiP obtained from TS or the crystalline phase αTi(HPO₄)₂∙H₂O, which is in an amorphous silica matrix obtained from a rutile–silica composition. Full article

Bioceramic materials, such as hydroxyapatite, Ca₁₀(PO₄)₆(OH)₂, (HAp), can be chemically bound to bone tissue; since they are bioactive and biocompatible. HAp, titanium oxide (TiO₂), and hydroxyapatite/titanium oxide (HAp/TiO₂) nanocomposite nanoparticles were obtained by ultrasound irradiation assisted by sol-gel and co-precipitation methods at different time intervals, using Ca(NO₃)₂•4H₂O, (NH₄)₂HPO₄, and TiOSO₄•xH₂O as calcium, phosphorus, and titanium sources, respectively. HAp, TiO₂, and HAp/TiO₂ nanocomposite powders were characterized by X-ray Diffraction (XRD) and Raman Spectroscopy. The percentages of anatase phase for TiO₂ and of monoclinic and hexagonal phases for HAp were quantified by Rietveld refinement. Furthermore, sample crystallinity in each material was enhanced by increasing the ultrasound irradiation time. The nanoparticle shape was semi-spherical, agglomerated, and between 17 and 20 nm in size. The agglomeration of particles in the samples was corroborated with a Field Emission Scanning Electron Microscope (FESEM). Full article

We report the synthesis of mesoporous TiO₂ nanostructures based on the decomposition of TiOSO₄ in aqueous alkaline solution at room temperature, followed by mild thermal treatment (110 °C) in an oven and suitable to yield up to 40 g of product per batch. The duration of the thermal treatment was found to be crucial to control crystalline phase composition, specific surface area, surface chemistry and, accordingly, the photocatalytic properties of the obtained TiO₂ nanocrystals. The thorough investigation of the prepared samples allowed us to explain the relationship between the structure of the obtained nanoparticles and their photocatalytic behavior, that was tested in a model reaction. In addition, the advantage of the mild treatment against a harsher calcination at 450 °C was illustrated. The proposed approach represents a facile and sustainable route to promptly access an effective photocatalyst, thus holding a significant promise for the development of solutions suitable to real technological application in environmental depollution. Full article

The kinetics of the sulfuric acid leaching of altered ilmenite, mechanisms, and process intensification methods were studied. The effect of changing the chemical composition during grinding was determined. The content of ilmenite and pseudorutile decreased from 5.3% to 3.1% and from 90.2% to 63.1%, respectively. Rutile increased from 4.5% to 28.7%, while a pseudobrookite new phase appeared in the amount of 5.1% after 2 h of grinding. It was found that the modification of raw material by sulfuric acid led to the increase of the decomposition rate, and at the same time, decreased when the ore was utilized due to an increase of insoluble TiO₂ content. Isothermal conditions were evaluated with H₂SO₄ concentration varying from 50 to 96%. The data obtained were described with the approximation of the contracting sphere model. It was shown for the first time that H₂SO₄ > 85 wt% causes a sharp constant decrease of titanium. Correlating these phenomena allows for the consideration of H₂SO₄·H₂O as reagents, rather than H₂SO₄ molecules. It was experimentally proven that at a temperature above 190 °C, the Ti leaching degree dropped, which is explained by the formation of polymerized TiOSO₄. Finally, it was shown that adding NaF reduced the activation energy to 45 kJ/mol. Full article