Titanium Sulfate Research Articles

Direct Amide Synthesis over Composite Magnetic Catalysts in a Continuous Flow Reactor

Composite magnetic catalysts containing different amounts of sulfated titania (33–50 wt %) have been prepared by means of high energy ball-milling between TiO2 and NiFe2O4. The catalysts have been characterized with N2 adsorption/desorption isotherms, XRD, temperature programmed oxidation (TPO) and vibrating sample magnetometer (VSM). The catalytic activity was measured in the reaction of aniline and 4-phenylbutyric acid in the continuous mode under conventional and inductive heating. The effect of catalyst loading in the reactor on reaction and deactivation has been studied, indicating the catalyst containing 50 wt % titania gave the highest reaction rate and least deactivation. The operation in a flow reactor under inductive heating increased the amide yield by 25% as compared to conventional heating. The initial reaction rate decreased by 30% after a period of 15 h on stream. The catalyst activity was fully restored after a treatment with an air flow at 400 °C.

Structure of the amorphous titania precursor phase of N-doped photocatalysts.

Amorphous titania samples prepared by ammonia solution neutralization of titanyl sulphate have been characterized by chemical and thermal analyses, and with reciprocal-space and real-space fitting of wide-angle synchrotron X-ray scattering data. A model that fits both the chemical and structural data comprises small segments of lepidocrocite-type layer that are offset by corner-sharing as in the monoclinic titanic acids H2TinO2n+1·mH2O. The amorphous phase composition that best fits the combined chemical and scattering data is [(NH4)3H21Ti20O52]·14H2O, where the formula within the brackets is the cluster composition and the H2O outside the brackets is physically adsorbed. The NH4+ cations are an integral part of the clusters and are bonded to layer anions at the corners of the offset layers, as occurs in the alkali metal stepped-layer titanates. The stepped-layer model is shown to give a consistent mechanism for the reaction of aqueous ammonia with solid hydrated titanyl sulphate, in which the amorphous product retains the exact size and shape of the reacting titanyl sulphate crystals.

Fluorine-regulated surface chemical state of titanium dioxide (TiO

Environmental context As a new type of photocatalytic material, nano-titanium dioxide can be applied in the field of energy and environmental protection. This research uses ammonium bifluoride to modify the titanium dioxide and analyses it in combination with interface chemistry theory, and finds that its photocatalytic efficiency has been greatly improved. This provides new ideas for wastewater treatment and pollutant degradation. Abstract Titanium dioxide (TiO2) was prepared by hydrothermally adjusting titanium sulfate with ammonium hydrogen fluoride. The UV-visible absorption spectra show that there was no significant redshift in the absorption sideband of the sample, but the addition of ammonium hydrogen fluoride affected the morphology and microstructure of the sample. When the molar ratio of F to Ti was 1.5, the specific surface area of TiO2 more than doubled, the surface complexation mode changed significantly and the number of surface-active sites increased by a factor of 16.24. The photocatalytic degradation measurements show that the decolourisation rate of the photocatalyst prepared by fluorine control was increased by 40 % compared with the uncontrolled sample. The analysis of the combined state of the catalyst surface shows that the photocatalytic degradation efficiency and the amount of deprotonated TiO− as well as the number of positively charged oxidation states of methylene blue are clearly correlated. Furthermore, the number of active sites of the catalyst increased and the electrostatic interaction between fluorine and titanium formed a F-Ti dipole moment, which intensified the interaction between the negatively charged TiO− ion and the positively charged quinone methylene blue molecule. The lone pair electron of N in the quinone methylene blue molecule and the 3d orbital of Ti formed a metastable complex through coordination, and demethylation of the methylene blue molecules was completed.

Redox-based colorimetric sensing of H2O2 after removal of antioxidants with ABTS radical oxidation

Monitoring and determining H2O2 in many industries, treatment plants and biochemical media is important because of its harmful effects even at low concentrations. This work proposes a redox-based colorimetric sensor for the determination of hydrogen peroxide in the presence of antioxidants which are known interferents causing positive errors. On the other hand, the widely used peroxidase-based methods are interfered by enzyme inhibitors. The proposed method consists of two stages, namely antioxidant removal and H2O2 determination. In the first step, antioxidants were removed simply using ABTS radical (ABTS+) oxidant produced by persulfate. After antioxidant elimination, H2O2 in samples was determined by using the CUPRAC colorimetric sensor. The CUPRAC reagent, copper (II)-neocuproine (Cu(II)-Nc), immobilized on a Nafion persulfonate membrane was used for sensor preparation. The light blue Cu(II)-Nc was reduced by H2O2 to the yellow-orange colored Cu(I)-Nc chelate on the sensor, and the absorbance increase at 450 nm was recorded. The LOD and the LOQ values obtained for H2O2 were 0.33 and 1.10 µM, respectively. The proposed assay was validated in terms of linearity, additivity, precision and recovery. The H2O2 contents of spiked food extracts, synthetic serum and certain commercial products (i.e. food sterilization solution, whitening toothpaste and hair bleaching solution) were found to be comparable to the results of peroxidase-ABTS and titanyl sulfate reference assays. In addition, peroxide-type explosive triacetone triperoxide (TATP) was successfully determined in the presence of amine-type antioxidants. The proposed simple and low-cost assay is not inhibited by environmental agents (heavy metals, pesticides, sulfhydryl agents, etc.) adversely affecting enzymatic methods. It is additionally insensitive to turbidity and colored components of complex samples.

The effect of mechanochemical, microwave and hydrothermal modification of precipitated TiO2 on its physical-chemical and photocatalytic properties

The effects of the microwave (MWT), hydrothermal (HTT) and mechanochemical treatments (MChT) on the structure and physicochemical properties of TiO2 precipitated from titanium sulfate and chloride were investigated. The obtained materials were characterized using the N2 adsorption/desorption, XRD and XRF analysis, FTIR and UV–vis spectroscopy. Photo- and mechanocatalytic properties of the samples were also studied as regards the rhodamine B (RhB) degradation in the aqueous solution. All types of treatment cause significant changes in the porous structure of the samples. The XRD results showed the improvement of crystalline structure during MWT and HTT. As follows from the investigations, each way of modification results in the shift of the absorption edge towards higher wavelength values and promotes an increase in the photocatalytic activity in the process of rhodamine B degradation under visible irradiation. For the mechanocatalytic degradation, the antibate dependence of the rate constant of RhB degradation on the specific surface area of catalysts was established.

High-efficient removal of arsenite by coagulation with titanium xerogel coagulant

Coagulation with inorganic titanium (Ti) salts is a low-cost and high-efficiency technology for arsenic removal. However, the drastic decline of solution pH, which is caused by coagulation process, usually greatly reduces the removal efficiency of arsenite (As(III)). In this study, titanium xerogel coagulant (TXC) was employed for enhanced As(III) removal, and two common Ti-based coagulants, titanium sulfate (TS) and titanium tetrachloride (TC), were used as references. TXC outperformed TS and TC over the initial pH range of 5.0–10.0, especially under acidic condition, which was attributable to the moderate pH decline during TXC coagulation. TXC with dose of 10 mg Ti/L could eliminate above 90% of As(III) at pH 7.0 and 8.0. The maximum coagulation efficiency of the three Ti salts (10 mg Ti/L) at pH 8.0 followed an order of 625 mg/g Ti (TXC) > 588 mg/g Ti (TS) > 526 mg/g Ti (TC). The enhanced mechanisms involved in TXC coagulation were the strong adsorption ability of the in-situ formed flocs and binding affinity between As(III) and hydrolysates. TXC coagulation dominated by the unique network-like hydrolysates would generate in-situ flocs with more binding sites, and thus improved coagulation efficiency. Except for phosphate and silicate ions, the common water matrices did not greatly inhibit As(III) removal efficiency. In addition, TXC performed the highest As(III) removal efficiency in actual arsenic-containing wastewater. This study provided a high-efficient coagulant for As(III) pollution control, and shed light on the application potential of TXC in removing metalloid pollutants.

TiO2-SO42−: A recyclable heterogeneous catalyst for the microwave-mediated synthesis of benzylamino coumarin derivatives in water

Abstract A new and environmentally benign protocol was developed for the synthesis of a series of benzylamino coumarin derivatives via the multicomponent reactions of 4-hydroxycoumarin, aromatic aldehyde and cyclic secondary amine in water using sulfated titania (TiO2-SO42−) as a heterogeneous solid acid catalyst under microwave irradiation at 100 °C. The proposed method is advantageous due to its simple reaction procedure, high yield, easy work-up, short reaction time, and reusability of sulfated titania (TiO2-SO42−) and its high adaptability for the synthesis of benzylamino coumarin derivatives in good to excellent yields. The catalyst can be easily recovered and reused with almost the same catalytic activity. The structure of the benzylamino coumarin derivatives was confirmed by melting points, elemental analysis, IR, 1H, and 13C NMR and 2D NMR spectral data. Higher catalytic activity of sulfated titania (TiO2-SO42−) is due to its increased Bronsted acidity.

Titanium Oxide Films Prepared by Cathodic Electrodeposition Method

In this paper, titanium oxide (TiO2) films were prepared by cathodic electrodeposition using titanium oxysulfate (TiOSO4), potassium nitrate (KNO3), citric acid, and hydrogen peroxide (H2O2) as reactants. The article investigated the effect of citric acid and deposition temperature on the structure and electrochemical properties of TiO2 films. The results indicated that hydrous TiO2 thin films were prepared at 60°C when no citric acid was added, while thin films containing hydrous TiO2 and anatase phase were fabricated at 60–75°C when citric acid was added. It was found that adding citric acid and raising the reaction temperature (60–75°C) were beneficial to reduce crack width until cracks disappeared. Adding citric acid facilitated phase transition from hydrous TiO2 to anatase. Continuous and uniform TiO2 thin film was prepared at 75°C, which was found to have ideal capacitive behavior with a rectangular cyclic voltammogram and high photocurrent performance with photocurrent 2.89 μA, which is several times higher than that of cracked samples.

Sulfated titania (TiO2-SO42−) as an efficient and reusable solid acid catalyst for the multi-component synthesis of highly functionalized piperidines

An efficient and one-pot procedures have been developed for the synthesis of highly functionalized piperidine derivatives via pseudo five-component reactions in the presence of sulfated titania (TiO2-SO42−) as a heterogeneous solid acid catalyst was reported for the first time. The pseudo five-component reactions of aromatic aldehydes, aromatic amines, and β-keto esters catalysed by sulfated titania (TiO2-SO42−) in methanol at 70°C provides highly functionalized piperidine derivatives in good to excellent yields. The structure as well as the relative stereochemistry of these functionalized piperidines was confirmed by melting points, IR, 1H, and 13C NMR spectral data and single crystal X-Ray analysis. This sulfated titania (TiO2-SO42−) gives an good to excellent yield with short reaction time and is inexpensive, easily recyclable catalytic material for this reaction. Higher catalytic activity of sulfated titania (TiO2-SO42−) is due to its increased Bronsted acidity.

Отходы чистят отходы.

Cost-effective and eco-friendly methods of novel sorbentproductionbased on a Ti, Ca and Mg phosphates have been carried out. The solid precursors were ammonium titanyl sulfate and calcined dolomite, which were used as titanium, calcium, and magnesium sources. The heterogeneous synthesis procedure in-cludes stepwise interaction between solid precursors and liquid phosphorus-containing agents. In mech-anochemical way to obtain the sorbent was usedonly solid reactants. Synthesiswas carriedout in a plan-etary ball mill. The final product wasa composite material, whichconsistsof the following components: TiO(OH)H2PO4·H2O, Ti(HPO4)2·H2O, CaHPO4·2H2O, MgНPO4·3H2O, and NH4MgPO4·6H2O. The new sorbent shows high sorption ability towards radionuclides in multicomponent liquid radioactive waste (LRW) sys-tems. Purification effect is based on both precipitation and ion exchange mechanism.

Оценка эффективности методов очистки сточных вод гальванического производства от аммиачно-тартратных комплексов меди (II)

Wastewater purification from heavy metal compounds is a complex and urgent task. One of the main sources of pollution of the environment with ions of heavy metals is the wastewater, i.e., washing, of the electro-plating processes. Complex electrolytes based on copper compounds are stable in a wide pH range and, when released into water, cannot be removed by the traditional methods, such as neutralization and precipitation. The study estimated the efficiency of various methods of physicochemical water purification for removing complex ammonia-tartrate copper (II) complexes from water. Findings of research show that titanyl sulfate is most effective in water purification using coagulants. The efficiency of purification with the use of titanium compounds reaches 85 %, which is on average 30--40 % higher than when using traditional coagulants based on aluminum or iron compounds. Electrocoagulation processes make it possible to effectively remove complex copper compounds from water due to a combination of the processes of organic component oxidation and coagulation with iron salts. It was found that advanced oxidation processes, which are based on the reaction with a hydroxyl radical, using hydrogen peroxide, i.e., Fenton processes, make it possible to purify wastewater from copper compounds by 99.9 %. Despite the high efficiency, it is advisable to use adsorption processes only at the stage of additional water purification from previously coagulated and oxidized pollutants

Facile preparation of effective flame retardant silk fabric by the metal salt adsorption approach

In this study, flame retardant (FR) functional silk fabric was prepared by the facile adsorption of metal salts (ferrous, aluminum and titanium sulfate) at low concentration. This study tried to provide a good understanding on the FR ability and action of metal salts on silk fabric. The morphological structure and functional groups of silk fiber before and after treatment were studied. The thermal stability, smoke generation ability and FR ability of the treated silk were evaluated. The iron, aluminum and titanium salts endowed silk fabric with self-extinction effect at a concentration of 0.1, 0.5 and 1.0 g/L, respectively. The metal salts also showed good washing resistance on silk fabric; for example, the aluminum salt treated silk still reached self-extinction after 10 robust washings, which is attributed to the complexation capacity of silk macromolecule with metal ions. The thermal stability and char residues analyses suggested the condensed phase FR mechanism for the treated silk, and the good ability to promote char formation contributed to their FR functionality. This study suggests that certain metal salts are effective enough to serve as suitable alternative to toxic halogen-based chemicals for enhancing fire safety of silk textiles.

Facile Synthesis of Highly Active Sulfated Titania Nanofibers for Viscous Acid-Catalytic Reactions

Well-shaped sulfated titania nanofibers were prepared by impregnation of hydrogen titanate with (NH4)2S2O8 and calcination. Various characterization results showed that sulfated titania nanofibers consisted of smooth-surface and long-size fibers with the diameter of dozens of nanometers. Moreover, acid characteristics of sulfated titania nanofibers exhibited the high acid content, multi-strength acid sites and large Bronsted/Lewis acid ratio. In low-viscosity esterification, sulfated titania nanofibers had 1.2 ~ 2.1 times the reaction rate of other sulfated titania and other typical solid acids. Simultaneously, sulfated titania nanofibers possessed the higher DS value of product than those by other solid acids in highly viscous cellulose acetylation (2.41 versus 2.06 ~ 2.21). Besides these, sulfated titania nanofibers could show the excellent recycling performance in viscous acid-catalytic reactions.

Influence of Inorganic Bases on the Structure of Titanium Dioxide-Based Microsheets.

Laboratory synthesis of microsheets of titanium dioxide from titanyl sulfate involves the use of ammonia solution, whereas another inorganic base is most likely to be employed at the industrial level, as ammonia is a toxic agent and therefore should be avoided according to European Union (EU) regulations. Selected nontoxic bases such as sodium, potassium, and lithium hydroxides have been tested as an alternative to ammonia solution to obtain amorphous and crystalline TiO2-based microsheets. The final products obtained at each step of the procedure (samples lyophilized and annealed at 230 and 800 °C) were analyzed with electron and atomic force microscopy, X-ray powder diffraction, thermal analysis, and Fourier transform infrared (FTIR) and Raman spectroscopies to determine their morphology and phase composition. The differences in the morphology of the obtained products were described in detail as well as phase and structural composition throughout the process. It was found that, in the last step of the synthesis, microsheets annealed at 800 °C were built of small rods and oval or platy crystalline particles depending on the base used. The temperature of formation of anatase, rutile, and alkali-metal titanates in correlation with the ionic radius of the alkali metal present in the sample was discussed.

Effect of sulfated metal oxides on the performance and stability of sulfonated poly (ether ether ketone) nanocomposite proton exchange membrane for fuel cell applications

In order to simultaneously improve the durability and performance of sulfonated poly (ether ether ketone) (SPEEK), series of hybrid membranes were prepared by doping an optimized amount of sulfated titania and sulfated zirconia-titania into the SPEEK matrix. The nanoparticles were synthesized using the sol-gel method and specified using XRD and EDS analysis. The solution casting method was used to prepare the membranes. Membrane characterization was performed through structural, morphological, thermochemical, and mechanical tests. The physicochemical characterization revealed that nanocomposite membranes are significantly improved compared with plain SPEEK. The single-cell performance test of nanocomposite based MEA record the power density peaks of 500mW cm−2 at 120°C and RH = 80%. Accordingly, sulfated metal oxide nanocomposite SPEEK-based membranes are promising alternative polymer electrolyte membranes for fuel cell applications.

Preparation of a novel nano-TiO2 photocatalytic composite using insoluble wood flour as bio-carrier and dissolved components as accelerant

Using NaOH/ urea solution to partially dissolve wood flour, a novel nano-TiO2 photocatalytic composite was prepared by hydrothermal method with insoluble wood flour as bio-carrier and dissolved components of wood flour as accelerant. SEM results showed that the control sample prepared without adding titanium sulfate consisted of insoluble wood flour and still possessed unbroken fibers after hydrothermal treatment. The control sample prepared without wood flour addition was only composed of TiO2 micro-particles. With assistant of the dissolve components of wood flour, nano-TiO2 with the size of 50−300 nm was well assembled on the surface of insoluble wood flour. The composite is composed of anatase TiO2 and insoluble wood flour and possess high specific surface area. The absorption edge of composite extended to the visible light range. The composite exhibited high removal rate of methylene blue, up to 97.7% within 120 min. This performance was even better than commercial TiO2 (P25) with the rate of 81.8%. The reused performance of the composite retains removal rate of 90.7% even after 5 cycles. The environment-friendly nano-TiO2 photocatalytic composite can be very useful for degrading refractory organic pollutants.

Anatase-rutile phase transformation and photocatalysis in peroxide gel route prepared TiO2 nanocrystals: Role of defect states

Peroxide gel method, utilizing titanyl sulfate as a titanium source, is employed to synthesize TiO2 nanocrystals. The nanoparticles are further annealed at different temperatures of 300, 500, 700, and 900 °C. XRD analysis reveals a phase pure anatase structure for the as-prepared sample and anatase-rutile mixed-phase for annealed TiO2 nanocrystals. UV–visible diffuse reflectance and Fourier transform infrared spectroscopic measurements also confirm the formation of anatase-rutile mixed phase for annealed samples. Micro-Raman spectra recorded for three different excitation wavelengths suggest the formation of rutile phase in the interior of the anatase nanoparticles upon annealing. Photocatalytic efficiencies of the TiO2 nanocrystals are evaluated by choosing methyl orange as a model dye under UV and simulated solar irradiations. Presence of defect states, mainly oxygen vacancies, that form subband states extending from shallow to the deep levels in TiO2 bandgap are confirmed from photoluminescence measurements. Among the TiO2 samples, the nanocrystals annealed at 300 °C shows the maximum photocatalytic activity. The observed variation in the photocatalytic activities of the TiO2 nanocrystals is explained as per the difference in the intensity ratio of the emission peaks corresponding to those of shallow and deep traps in the bandgap of the TiO2 nanocrystals.

Preparation of TiO2/Fe3O4 composite by sol-gel method and its photocatalytic activity for removal of Rhodamine B from water

The TiO2/Fe3O4 composite is a new kind of photocatalytic materials with magnetism. Using FeCl2, FeCl3, and titanyl sulfate as the main raw material, TiO2/Fe3O4 was synthesized by sol-gel process and 450 °C calcination for 2 h under a condition of hydrogen nitrogen mixture gas. The samples were characterized by powder X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The photocatalytic activity, reclaim and cyclic utilization of the TiO2/Fe3O4 composite were studied by using Rhodamine B as simulated wastewater. The results show that TiO2/Fe3O4 composite has good magnetic properties and excellent photocatalytic activity for removal of Rhodamine B from water, and it can come true well reclaim and recycling by using the electromagnet. The recovery efficiency of TiO2/Fe3O4 composite can reach above 90% at the first reclaiming. TiO2/Fe3O4 composite can be reused tree times without a significant photoactivity loss. It shows that TiO2/Fe3O4 composite is a kind of environmental photocatalyst with a wide application prospects.

Synthesis of 3D-structured Li4Ti5O12 from titanium(IV) oxysulfate (TiOSO4) solution as a highly sustainable anode material for lithium-ion batteries

Because of its excellent safety and sustainability, spinel-structured lithium titanate (LTO, Li4Ti5O12) has recently attracted intensive attention as a promising anode material for lithium-ion batteries (LIBs) for large-scale applications. However, several obstacles impede the use of LTO in practical applications, including its high cost and relatively low capacity due to poor electron conductivity. To reduce the synthesis cost and increase the efficiency of LTO, LTO microspheres assembled with nanoparticles were prepared from a titanium(IV) oxysulfate (TiOSO4) solution, which is generally produced during the sulfate process in titanium mining of ilmenite (FeTiO3). Before LTO microspheres were synthesized, 1–2 μm microsphere scaffolds consisting of TiO2 nanoparticles were prepared through the urea-based hydrolysis of TiOSO4. The LTO microspheres were obtained through a sequential hydrothermal reaction–calcination process using LiOH and the as-prepared TiO2 microsphere scaffolds. According to the synthesis conditions, LTO–TiO2 (LTO-500), nonporous LTO (LTO-800), and porous LTO (LTO-HT3-500) microspheres were synthesized. The electrochemical performances of the synthesized LTO microspheres were most strongly affected by the microspheres’ crystal size and surface area. The presence of TiO2 in the LTO microspheres also affected their performance. The LTO-HT3-500 microspheres (pure spinel LTO phase) showed an excellent initial discharge capacity of 158.7 mAh/g, superior cyclic ability (<7.3% capacity decay, 100 cycles at 1C), and rate capability (capacity loss 11%) at high current rates (0.1C–10C) because of their small crystal size (17.6 nm) and large specific surface area (44.4 m2/g). These results demonstrate that high-performance LTO microspheres for LIBs can be produced from TiOSO4 solution as a low-cost Ti source.

Воздействие некоторых сложных хемостимуляторов и модификаторов на термооксидирование InP

Воздействие некоторых сложных хемостимуляторов и модификаторов на термооксидирование InP