Search

Copyright of Science of Sintering is the property of National Library of Serbia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The activation of persulfate (PS) under UVA irradiation by two TiO 2 polymorphs (brookite and anatase) and titanate photocatalysts was evaluated for the simultaneous removal of the biocides methylisothiazolinone (MIT) and chloromethylisothiazolinone (CMIT), in ultrapure water and real sewage treatment plant water (SW). Titania and titanate samples were synthesized by a hydrothermal method and characterized by XRD, SEM, N 2 adsorption-desorption isotherms and UV-Vis DR. The reactions were performed in individual (brookite, anatase, titanate and PS) and hybrid (titania/PS and titanate/PS) systems and compared to those with TiO 2 -P25 as reference. In ultrapure water, the combined brookite/PS system showed a higher performance for MIT and CMIT abatement and a stronger synergistic effect between titania and PS than found in anatase/PS and titanate/PS systems, indicating the higher effectiveness of the brookite phase for PS activation under UVA. The use of SW water revealed the strong inhibitory effect of matrix constituents in the individual brookite, anatase and PS systems, which exhibited a low performance. However, the kinetics of MIT/CMIT in SW were greatly enhanced in the hybrid TiO 2 /PS systems, especially with brookite, leading to an efficient degradation of both pollutants and the decrease of total organic carbon (TOC). The addition of chemical scavengers showed a similar reactivity of HO• towards both isothiazolinones whereas a preferential attack of SO 4 • − to MIT was observed, demonstrating the selective nature of SO 4 • −. [Display omitted] [ABSTRACT FROM AUTHOR]

Copyright of Chemical Industry / Hemijska Industrija is the property of Association of Chemical Engineers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• One-step hydrothermal method of synthesizing of Ag/TiO 2 nanofibers was developed. • Silver incorporation can self-assembly onto the TiO 2 NFs after the optimal calcination, constructing the heterostructure. • Ag/TiO 2 nanofibers possess the enormous potential of photocatalyst used in pollutant removal and hydrogen evolution. Photocatalysis has been regarded as a promising process for pollution removal and green energy. TiO 2 nanofibers synthesized by the hydrothermal method presents high crystalline and performs excellently due to the efficient charge transport. For practical use, we designed an autoclave with a 1,000 cm3 of Teflon-liner inside and stainless steel outside for the hydrothermal synthesis of Ag/TiO 2 NFs. Various parameters of the process, including reaction temperature, doping concentration, and calcination temperature, were investigated to provide a reliable and optimal process. Through the hydrothermal reaction, TiO 2 particles transformed into sodium titanate nanorods, and further refilled the hollow channel. With the proton exchange using diluted hydrochloric acid, the precipitated Ag nanoparticles were leached but appeared again on the surface of Ag/TiO 2 nanofibers after the calcination. Silver incorporation enhanced the absorption in the visible region and precipitated onto the TiO 2 NFs surface after the optimal calcination, constructing the heterostructure. It dominated the photocatalytic performance of pollutant degradation and water splitting. The unveiling of silver surface precipitation gives a clear illustration in the scaled-up hydrothermal method of Ag/TiO 2 , providing an efficient way for nanomaterial fabrication. [Display omitted] [ABSTRACT FROM AUTHOR]

• 3D hollow ZIF-67 MOF based photocatalyst with excellent photo-catalytic performance was synthesized. • The H-ZIF-67@PDA@TiO 2 sample exhibited strongest photo-current intensity. • The photodegradation kinetic follows the Langmuir-Hinshelwood (L-H) model. • Superoxide free radicals (•O 2 −) and hydroxyl radicals (•OH) were the primary and secondary reactive species during photo-degradation. Photocatalytic technology is considered the most promising green technology for the degradation and removal of organic pollutants. In this paper, an innovative multifunctional photocatalytic material has been successfully prepared. The zeolitic-imidazolate-framework-67 (ZIF-67) was first synthesized by an easy and green approach. Then, a polydopamine (PDA) mid-layer was incorporated on its surface via dopamine self-polymerization, which not only serves as a stable linking agent, but also increases the amount of visible light captured and reduces the recombination of photogenerated electron-hole pairs. After the hydrolysis and hydrothermal process of tetrabutyl orthotitanate, the TiO 2 nanoparticles were uniformly grafted on the surface, and finally, the hollow ZIF-67@PDA@TiO 2 was successfully obtained. The prepared H-ZIF-67@PDA@TiO 2 photocatalyst was characterized by various techniques, and further used for the photo degradation of a variety of dyes in wastewater in the presence of visible light. A degradation rate of almost 100% was achieved for Acid Fuchsin and Congo Red within 40 min, followed by Erythrosine B and Rose Bengal with a 99% degradation rate within 150 min. Moreover, the ZIF-67-based photocatalyst exhibited high stability and recyclability and maintained an excellent photocatalytic performance during continued cycling. Furthermore, the superoxide radical (•O 2 −) and the hydroxyl radical (•OH) were the primary and secondary reactive species during photodegradation. Overall, the excellent performance of this simple photocatalyst was clearly demonstrated, and its numerous advantages, such as low energy consumption, low cost, non-toxicity, and environmental friendliness, showing promising potential for its practical implementation. [Display omitted] [ABSTRACT FROM AUTHOR]

A novel approach was developed to reduce the corrosion rate of magnesium (Mg) metal, utilising titanate coatings. Magnetron sputtering was used to deposit ca. 500 nm titanium (Ti) coatings onto pure Mg discs, followed by hydrothermal conversion and ion exchange reactions to produce sodium and calcium titanate coatings. SEM confirmed the characteristic nanoporous structure of sodium and calcium titanate, with thicknesses ranging from ca. 0.8 to 1.4 µm. XPS analysis confirmed the presence of Ti4+—O, Na—O, and Ca—O bonding, whilst Raman spectroscopy demonstrated characteristic vibrational modes (such as TiO 6 octahedral vibrations) of the sodium and calcium titanate perovskite structure. Furthermore, corrosion studies through potentiodynamic polarisation measurements demonstrated the NB/NH CaTC samples to be superior in reducing Mg degradation, compared to other samples tested, through an increase in E corr from −1.49 to −1.33 V, and the reduction in corrosion current density, i corr , from 0.31 to 0.06 mA/cm2 for Mg and NB/NH CaTC samples, respectively. There was a clear trend noted for the NB/NH samples, which showed an increase in E corr to more positive values in the following order: Mg < Ti coated < NaTC < CaTC. These nanoporous titanate coatings have potential to be applied onto degradable plates for bone fracture fixation, or other orthopaedic applications. [ABSTRACT FROM AUTHOR]

Copyright of Science of Sintering is the property of National Library of Serbia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The use of lithium titanate (Li4Ti5O12, LTO) for the negative electrode in lithium ion batteries has attracted enormous attention owing to its fast charging capability, high power, safe operating voltage window and stable structure ("zero strain") during cycling. Researchers have investigated the formation of the solid electrolyte interface (SEI) of the LTO electrode, which prevents gassing issue and leads to longer cycle life. In this study, the solid-state diffusion property of LTO at room temperature was characterized using AC impedance spectroscopy at different states of charge (SOC) during charge and discharge to reveal the dependency of the lithium diffusion coefficient on SOC. Meanwhile the formation and growth of the solid electrolyte interface (SEI) on the LTO electrode using an electrolyte containing Silatronix OS3® additive were investigated using X-ray photoelectron spectroscopy (XPS). The composition of the SEI and its evolution due to cycling with the OS3® additive was compared to that with a commercial electrolyte. Half-cell coin cells of LTO vs lithium metal were formed and cycled at room temperature for over 200 cycles, where the resistance increase, as measured by impedance spectroscopy, is correlated to the SEI growth. Electrode samples were analyzed in the pristine state, after formation, and after 200 cycles. XPS results showed that a thin layer of SEI is formed during the first two formation cycles and the composition of the SEI on the surface of the LTO electrode varied with increasing cycle number. Based on the escape depths of Ti 3 s and Ti 2p regions, the SEI after formation is thicker than 5.5 nm but is less than 7.0 nm for both the OS3® and A7 electrolytes. Based on Ar-ion depth profiling, the SEI thickness in terms of the equivalent thickness of SiO2 after 200 cycles in coin cell configuration is estimated to be near 14 nm for both the OS3® and A7 electrolytes. A much higher fluorine content (F 1s peak) was found in the SEI formed with the OS3® electrolyte than the SEI formed with the commercial A7 electrolyte. [ABSTRACT FROM AUTHOR]

• Copper doping into zinc titanate improved the resistance of H 2 in desulfurization. • Cu-incorporation enhanced the separation of photo-induced pairs. • Cu loaded zinc titanate as a promising material for both H 2 S and dye removal. Multifunctionality is of a paramount significance in the case of metal oxide-based material. In the present study, Cu-doped zinc titanates in different Cu/Zn weight ratios were prepared with co-precipitation method to utilize as an adsorbent and a photocatalysts for H 2 S removal and dye degradation, respectively. The structural and morphological analyses were carried out using XRD, XPS, SEM and BET. The experiment results showed that the catalysts had a desulfurization ability with the Cu/Zn weight ratio of 0.06:1, which H 2 S in the feed was captured with 100% efficiency in N 2 atmosphere at 750 °C during 5 h, also the removal decreased to 57% in a reducing atmosphere at the end of 5 h. The appropriate Cu loading content could lead to the high active and low apparent activation energy. In addition, the Cu-based catalyst showed an excellent photocatalytic activity under UV light irradiation, which the degradation of Orange II (OII) was found to be 80% at the end of 3 h. The metal loading reduced the band-gap and increased oxygen vacancies of zinc titanate. The reactive adsorptive desulfurization and excellent photocatalytic activity results demonstrate Cu loaded zinc titanate as a promising material for multifunctional applications. [ABSTRACT FROM AUTHOR]

• Hybrid titanate nanostructures for CO 2 transformation to cyclic carbonates. • TNT-[IL][X] with [Cl−] and [BF 4 −] showed highest activity for styrene carbonate synthesis. • High reactivity of styrene oxide and epichlorohydrin were corroborated by DFT calculations using reactivity descriptors. Hybrid nanostructures were produced from several ionic liquids (ILs) anchored on titanate nanotubes (TNT). Ionic liquids ILs composed by the 1-methyl-3-(3-trimethoxysilylpropyl)imidazolium cation associated with the [Cl−], [BF 4 −], [PF 6 −] or [Tf 2 N−] anions were studied. The highest anchored amounts of IL were obtained with the [Cl−] and [Tf 2 N−] anions, respectively, of 31.5 and 43.5 % w/w. These hybrid nanostructures were used in the direct conversion of CO 2 to cyclic carbonates through the coupling reaction with various epoxides (epichlorohydrin, styrene oxide, glycidyl isopropyl ether, and propylene oxide). With styrene oxide, the best results were obtained using the [Cl−] and [BF 4 −] IL, showing TON values of 35.6 and 18.4, and TOF values of 17.2 and 9.2 h−1, respectively. The TNT-[IL][Cl] was also used with different epoxides (i.e. epichlorohydrin, styrene oxide, glycidyl isopropyl ether and propylene oxide) being more reactive in the reactions with epichlorohydrin (TON = 86.3, TOF =21.6 h−1) and styrene oxide (TON = 47.0 TOF =11.7 h−1). Theoretical studies showed that the high reactivity of styrene oxide can be associated with their lower HOMO-LUMO energy gap, while epichlorohydrin presented high electron withdrawing effect by chlorine, generating the higher electronegativity. Besides that, by NBO analysis, both molecules presented lower donor – acceptor interact energy which may favor the opening of the ring. [ABSTRACT FROM AUTHOR]

Life Cycle Assessment (LCA), a computational tool for enabling sustainable product design decision making, faces challenges in the interpretation phase, where conclusions are drawn for improvement recommendations. This necessitate the need to incorporate into LCA management-relevant theoretical underpinnings to strengthen decision-making processes. Comparative LCA case studies of lead-based piezoelectric material (lead zirconate titanate – PZT) and lead-free alternatives (potassium sodium niobate – KNN, sodium bismuth titanate – NBT), was employed to demonstrate how two theoretical lenses, namely Normal Accident Theory (NAT) and the Satisficing Framework, are used inductively to enhance decision making regarding unintended consequences in the value chain. By operationalising NAT, which has hitherto focused on the consequences of physical accidents, as a life cycle engineering-based methodology, NAT attributes of interactive complexity and tight coupling was revealed in piezoelectric materials, based on environmental systems' predictability, observability , and applicability. This led to the introduction of Environmental Impact Accident (EIA) as a new concept, facilitating an early assessment of the associated complexities influencing the sustainability credentials of piezoelectric materials whilst informing mitigation strategies. However, when considering multiple objectives that conflict or trade-off between alternative piezoelectric materials with different environmental and health impacts across the value chain, a conundrum is created but resolved using the Satisficing Framework. The paper concludes by proposing theoretical and practical policy options for incorporating LCA into product life cycle decision making. Of the conceptual framework detailing the methodological processes of integrating theoretical lenses of Normal Accident Theory and Satisficing Framework into LCA for sustainability decision-making. [Display omitted] [ABSTRACT FROM AUTHOR]

• Three Ni-containing perovskites are compared for activity in methane oxidation. • All materials give steady production of syngas in repetitive CH 4 /O 2 cycles. • The solid-state synthesized catalyst performs best but requires activation. • The complexation-made catalyst shows a high activity but deactivates in CH 4. • Synthesis conditions and material compositions are critical to good catalysts. Three perovskites of nickel-doped lanthanum strontium titanate (LSTN) were made and compared for their activity toward methane oxidation. The perovskite was synthesized separately via solid-state reaction, citrate complexation, and microwave-assisted methods. The perovskite from solid state reaction gave the highest activity of syngas production in repetitive redox cycles without any deterioration, demonstrating a great potential for use in chemical looping technology. Nevertheless, the material required activation in methane, as evidenced in studies of temperature-programmed surface reaction. On the contrary, the perovskite from the complexation method behaved completely different while the microwave-synthesized one gives the poorest activity. The variation of the activity was correlated with the distinct structure from different synthesis routes, which influences where a metal phase resides and how the metal anchors onto host oxides. The information obtained here would be of great benefit in making good material with desirable properties for catalysis and potential applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Gassing at elevated temperature is the main reason for the performance degradation of lithium titanate (Li4Ti5O12, LTO) batteries. In this study, an in-situ device was developed and used to study on-line the transient gassing of custom-made 4.5Ah LTO/NCM pouch batteries at 1C cycling at 55°C. The gas volume and internal pressure of the batteries were recorded on-line for 1000 h, and the composition of the gas components at different times was also analyzed by on-line gas chromatography. The results show that H2 and CO2 are the main gas components. The H2 percentage decreases, while the CO2 percentage increases gradually during the process of gassing. According to the rate-controlling step of gassing from H2 formation reaction to CO2, a stage-by-stage mixed gassing mechanism is proposed, where the water decomposition is dominant in the initial stage and solvent decomposition is dominant in the subsequent stage. The gassing of LTO batteries aged at 55°C was studied on-line at different states of charge (0%, 50%, 100% SOC). The results show that the volume and composition of the gas are essentially independent of the SOC of batteries and that formation of SEI at LTO interface is the main reason for the gassing rate reduction when aged and cycled (final phase) at 55°C. [ABSTRACT FROM AUTHOR]

• Titanate nanosheets and nanotubes were hydrothermally fabricated by changing reaction times. • Platinum-doped titanate nanocomposites were successfully synthesized by facile photoreduction methods. • Adsorption of cationic dyes on high surface-area and negatively charged titanate nanomaterials was enhanced. • Deposition of pt on titanate nanomaterials improved their photocatalytic ability of cationic dyes. • Photocatalytic activity of 0.5 wt% Pt-doped titanate nanosheets for cationic dyes was the highest under UV irradiation. In this study, two types of titanate nanomaterials (TNMs) including titanate nanosheets (TNS) and titanate nanotubes (TNT) were hydrothermally prepared by controlling reaction times, and then the platinum (Pt)-doped TNMs were fabricated. The photocatalytic performance of as-prepared materials was compared with that of the commercially available TiO 2 P25. It was revealed that changing the morphology of TiO 2 particles could enhance their adsorption ability and photocatalytic activity for the removal of cationic dyes from water. In particular, all prepared materials displayed greater removal of methylene blue than of P25 through the synergy of adsorption and photocatalysis; however, such an effect was not so pronounced for anionic dyes. For cationic dyes (methylene blue and rhodamine B) and anionic dyes (methyl orange and naphthol blue–black), TNT presented higher photocatalytic activity than TNS. The TNMs, after Pt doping, significantly enhanced photocatalytic activity compared to the pristine ones. Remarkably, 0.5% by weight Pt-doped TNS achieved 100% removal of methylene blue and rhodamine B after 120 min and 140 min of UV irradiation, respectively, outperforming P25, although Pt-doped TNMs showed lower photocatalytic performance than P25 for anionic dyes. [ABSTRACT FROM AUTHOR]

• A series of MWCNTs synthesized via sol–gel method. • Characterized using XRD, SEM, N 2 adsorption–desorption and diffused reflectance. • Two textile dyes has been examined systematically by considering the different ratios of TiO 2. • The photocatalytic degradation rate of MWCNTs and the synthesized nanocomposites has been evaluated. • The MWCNTs/10%TiO 2 sample have a higher efficiently which can be used for the photodegradation of the two textile dyes. Multi-walled carbon nanotubes/titanium dioxide nanocomposites were successfully synthesized by Sol-Gel method using new different ratios of tetrabutyl titanate and functionalized MWCNTs as the starting precursors. The synthesized Multi-walled carbon nanotubes/different titanium dioxide percentages (MWCNTs/3, 6 and 10%TiO 2) nanocomposites were characterized using XRD, SEM and N 2 Adsorption-Desorption techniques. The optical band gap was estimated for MWCNTs and MWCNTs with different TiO 2 percentages by Kubelka-Munk equation giving 3.72, 2.92, 2.83, 2.71 eV values respectively. The synthesized nanocomposites were used as photocatalyst for decontamination of two local textile Dianix Blue and Vat Green 1 Dyes which commonly used in dyeing manufacture in local market. [ABSTRACT FROM AUTHOR]

Bismuth titanate (Bi4Ti3O12) ceramics, so-called BiT, have many modern applications in microelectronics, sensors, and capacitors. In this study, the related solutions for fabricating BiT thin films were prepared and, then, coated on glass substrates by using the sol-gel technique and the spin coating instrument. The X-ray diffraction patterns of our samples indicated that the crystalline phases of the BiT were orthorhombic. Based on the transmission-spectra analysis, the samples are transparent in a visible spectrum, and their optical energy gaps were found to be 3.36 eV and 3.41 eV for the BiT thin films annealed at 600°C and 650°C, respectively. Other physical quantities, such as refractive index, thickness, extinction coefficient, and dielectric constant, were estimated by Swanepoel's method. The results show that as the annealing temperature rises, the real part of the dielectric constant becomes larger, that is, our samples are good dielectric materials. [ABSTRACT FROM AUTHOR]

Constructed wetlands are an environmentally friendly and economically efficient sewage treatment technology, with fillers playing an important role in treatment processes. However, traditional wetland fillers (e.g. zeolite) are known to be imperfect because of their low adsorption capacity. In this paper, the adsorbent sodium titanate nano fillers (T3-F) was synthesized as an alternative to traditional filler with sodium titanate nanofibers (T3) as the raw material, epoxy adhesive as the adhesive agent and NH 4 HCO 3 as the pore-making agent. The properties of T3-F were characterized by powder X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), porosity. The effect of different parameters such as pH, co-existing ions, contact time, initial metal ion concentrations and temperature was investigated for heavy metal adsorption. The results showed that the adsorption of heavy metal by T3-F followed the pseudo-second-order kinetic and Langmuir isotherm models. The maximum adsorption capacities for Cu2+, Pb2+, Zn2+, Cd2+ were about 1.5–1.98 mmol/g, which were 4–5 times that of zeolite, the traditional commonly used filler. Moreover, T3-F could entrap toxic ions irreversibly and maintain structural stability in the adsorption process, which solved the issue of secondary pollution. In the presence of competing ions, the adsorption efficiency for Pb2+ was not reduced significantly. Adsorption was strongest at high pH. From the results and characterization, an adsorption mechanism was suggested. This study lays a foundation for the practical application of T3-F as a constructed wetland filler in the future. Image 1 • A new constructed wetland fillers was prepared by sodium titanate nanofibers. • Fillers show excellent adsorption ability towards Cu2+, Pb2+, Zn2+, Cd2+ ions. • Adsorption occurs through ion exchange mechanism. • Fillers could entrap toxic ions irreversibly. The filler can effectively adsorb heavy metal ions and permanently trap toxic cations in the fiber. [ABSTRACT FROM AUTHOR]

Due to the rapid growth of global population, new, fast and reliable methods must be developed to purify contaminated water. Various photocatalysts have been developed to remove organic dyes from water. Herein, Ag doped BaTiO 3 has been synthesized using a facile solvothermal method and its excellent photocatalytic activities were demonstrated in degradation of both anionic and cationic dyes under visible light illumination. Ag doped BaTiO 3 nanoparticles showed greater efficacy in the degradation of methylene blue (MB) and eosin yellow (EY) than undoped BaTiO 3 nanoparticles, which makes them a better candidate for photocatalysis. 1.0 AgBT sample showed the highest photocatalytic activity for MB (99.1 % in 100 min) and EY (99.3 % in 60 min) dye degradation compared with those of other samples. Further, the trapping experiments revealed that hydroxyl radicals and holes are the active species in the photocatalytic process of MB and EY dye degradation and recycle test showed excellent stability of the synthesized material. [Display omitted] • Synthesis of silver doped BaTiO 3 by one pot solvothermal approach. • 99.1 % photocatalytic degradation of MB dye in 100 min. • 99.3 % photocatalytic degradation of EY dye in 60 min. [ABSTRACT FROM AUTHOR]

Ultimate properties of a porous ceramic is highly process dependent. In this study, prevalent porous ceramics fabrication methods (Freeze casting, Foam reticulation and Burnable Plastic Sphere (BURPS) method) have been compared by fabricating the porous lead zirconate titanate (PZT) based piezoelectric ceramics. Field emission scanning electron microscopy (FESEM) studies were performed to analyse the pore size and distribution of the ceramics. Hydrostatic co-efficients increased tremendously on incorporation of porosity which led to Hydrostatic Figure of Merit of 7480 in Foam reticulation samples (porosity 86 per cent). The three dimensionally interconnected networks in the freeze casted samples led to lowest acoustic impedance (6 MRayls) despite not having the lowest density. [ABSTRACT FROM AUTHOR]

Abstract The increasing presence of chemicals and pharmaceuticals in rivers, lakes, and groundwater among others, represents a latent threat both to ecosystems and to human health. Conventional treatment methods for water hardly eliminate these pollutants, which are usually dissolved in low concentrations (μgL−1 or ngL−1). Therefore, the use of nanomaterials represents a viable alternative to eliminate them. Titanate nanotubes have been successfully used in adsorption of organic dyes as well as heavy metals, however, their use as an adsorbent of pharmaceuticals and other organic pollutants has been scarcely studied. In this work, unmodified titanate nanotubes as well as modified titanate nanotubes by using a surfactant, were synthesized and characterized to study the adsorption of six organic pollutants of interest through first and second order kinetic models, as well as, adsorption isotherms of Freundlich and Langmuir. The synthesized nanotubes showed good efficiency for the adsorption of persistent organic compounds, reaching a maximum adsorption percentage of 83%, 78%, 54%, 43%, 30% and 47% for 2,4,6-trichlorophenol, oxytetracycline, 2,4-dichlorophenol, tolazamide, captopril, and metformin respectively. Moreover, removal of pollutants was also successfully carried out in groundwater samples. [ABSTRACT FROM AUTHOR]

The hierarchical core-shell and yolk-shell magnetic titanate nanosheets (Fe 3 O 4 @TNS) were successfully synthesized by employing magnetic nanoparticles (NPs) as interior core and intercrossed titanate nanostructures (NSs) as exterior shell. The as-prepared magnetic Fe 3 O 4 @TNS nanosheets had high specific areas (114.9 m 2  g −1 for core-shell Fe 3 O 4 @TNS and 130.1 m 2  g −1 for yolk-shell Fe 3 O 4 @TNS). Taking advantage of the unique multilayer structure, the nanosheets were suitable for eliminating U(VI) from polluted water environment. The sorption was strongly affected by pH values and weakly influenced by ionic strength, suggesting that the sorption of U(VI) on Fe 3 O 4 @TNS was mainly dominated by ion exchange and outer-sphere surface complexion. The maximum sorption capacities ( Q max ) calculated from the Langmuir model were 68.59, 121.36 and 264.55 mg g −1 for core-shell Fe 3 O 4 @TNS and 82.85, 173.01 and 283.29 mg g −1 for yolk-shell Fe 3 O 4 @TNS, at 298 K, 313 K and 328 K, respectively. Thermodynamic parameters (Δ H 0 , Δ S 0 and Δ G 0 ) demonstrated that the sorption process was endothermic and spontaneous. Based on X-ray photoelectron spectroscopy (XPS) analyses, the sorption mechanism was confirmed to be cation-exchange between interlayered Na + and UO 2 2+ . The yolk-shell Fe 3 O 4 @TNS had more extraordinary sorption efficiency than core-shell Fe 3 O 4 @TNS since the yolk-shell structure provided internal void space inside the titanate shell to accommodate more exchangeable active sites. The flexible recollection and high efficient sorption capacity made core-shell and yolk-shell Fe 3 O 4 @TNS nanosheets promising materials to eliminate U(VI) or other actinides in wastewater cleanup applications. [ABSTRACT FROM AUTHOR]

In this work, we report on the fabrication of continuous and uniform thin films by a solid state reaction. The fabrication of spinel Li4Ti5O12 thin films was demonstrated by solid state reaction between TiO2 and Li2CO3 stacked-layers upon thermal annealing. The TiO2 layer was prepared by physical vapor deposition or atomic layer deposition, whereas the Li2CO3 layer was deposited by chemical solution deposition or atomic layer deposition. The solid state reaction and obtained material properties were investigated on planar substrates. It was found that continuous films with crystalline and stoichiometric Li4Ti5O12 can be formed by solid state reaction at temperatures higher than 650°C. The prepared films exhibited Li-ion intercalation characteristics for Li4Ti5O12 spinel with the typical flat plateau at 1.55 V (vs Li+/Li) for both charging and discharging. The theoretical capacity of 612 mAh cm-3 was obtained at slow charging rate of 0.1 C with still 45% capacity attainable at 20 C. Interestingly, it was found that the kinetics is strongly dependent on the current collector substrate used. A TiN substrate provided faster Li4Ti5O12 electrode kinetics than a Pt substrate, despite a thin anatase interlayer at the TiN/TiO2/ Li4Ti5O12 interface, showing the importance of interface or work function matching for high rate lithiation/delithiation performance. In addition, the potential of conformal Li4Ti15O12 thin films on high aspect ratio structures was demonstrated. [ABSTRACT FROM AUTHOR]

Au decorated Co doped titanate nanotubes (TNT) was prepared for selective removal of methylene blue (MB) dye followed by selective photocatalytic degradation under solar light in presence of another highly concentrated dyes. The adsorption capacity of Co doped TNT was found to be increased with increasing Co content due to the increase in the number of pores and thus increase in surface area. Due to the high concentration of MB, Co doped TNT was completely covered by MB molecules and become difficult for light to Path though or absorbed by the Co doped TNT catalyst. In order to provide some photocatalytic characteristics for the catalyst, the doped TNTs were calcined to enhance the crystallinity and thus enhancing the photocatalytic activity, but the degradation rate was very low. Thus, another direction was started by reducing the adsorption ability of Co doped TNT through coating its surface by poly(allylamine hydrochloride), which changed the surface charge of the tubes to be positive and facilitate the electrostatic attachment of Au nanoparticles (15 nm). The synergetic effect of plasmonic Au nanoparticles in addition to adsorption and catalytic properties of Co doped TNT make the new composite promising catalyst for degradation of organic pollutants. It shows a good selectivity for adsorption and photocatalytic degradation of MB dye from dyes mixture. The obtained results indicate that Au decorated Co doped TNT will have a great effect on the development of selective environmental water treatment technologies specifically on flow challenges confronted by the wastewater treatment area. [ABSTRACT FROM AUTHOR]

Copyright of Science of Sintering is the property of National Library of Serbia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Growing interest in radioactive effluent treatment, especially after the Fukushima nuclear accident, has led to the development of new, increasingly efficient mineral sorbents. The sorbents currently attracting the most attention are materials dedicated to strontium extraction. The Ba-titanate material investigated here, combining several sorption mechanisms, has a high capacity and selectivity for strontium with a distribution coefficient, K d , of 863 mL g −1 , obtained from a batch sorption test with seawater ([Sr] = 9 × 10 −5 mol L −1 ; titanate concentration, 1 g L −1 ). This K d is six times higher than that of Na-titanate, one of the strontium sorbents used for multi-nuclide removal at the Fukushima-Daiichi nuclear power station. Upon contact with the sulfate-containing effluent, Sr extraction proceeds by ion exchange with the Ba ions inserted in the material and by coprecipitation with insoluble barium sulfate formed at the surface of the titanate grains. [ABSTRACT FROM AUTHOR]

An efficient photocatalytic reactor to remove pollutants from either water or air relies on highly active photocatalytic thin films on appropriate substrates, which contribute to both light harvesting and pollutant molecules transfer. In this investigation, few-layer titanate nanobelts were deposited on metallic Ti mesh using hydrogen peroxide solution, which were then subjected to a subsequent hot water treatment to achieve crystallized titania nanorod arrays. The three-dimensional arrays of nanorods formed on Ti mesh (three layers overlapped) exhibited an exceptional high efficiency when utilized to assist photodegradation of rhodamine B in water under UV light illumination, which is 25 times that of P25 film, and even 1.3 times that of P25 nanoparticles in a slurry system. For photodegradation of phenol in water, the three-layer Ti mesh also exhibited a reaction rate constant 6.9 times that of P25 film. The reduced band gap, abundant surface hydroxyl groups, and mixed phase effects arising from the low temperature approach contribute to the high photocatalytic activity. [ABSTRACT FROM AUTHOR]

Silane is a dominant coupler that is widely used in dentistry to promote adhesion among the components of dental composites. Silica-based fillers can be easily silanized because of their similarly ordered structure. However, silane is hydrolytically degraded in the aqueous oral environment and inefficiently bonds to non-silica fillers. Thus, the development of hydrolytically stable dental composites is an important objective in the research on dental materials. Titanate coupling agents (TCAs) exhibit satisfactory interfacial bonding, enhanced homogeneous filler dispersion, and improved mechanical properties of the composites. Titanates also provide superior hydrolytic stability in wet environments, which should be considered in fabricating dental composites. The addition of a small amount of titanates can improve the resistance of the composites to moisture. This paper reviews the effects of the instability of silanes in moisture on the performance of dental composites and presents TCAs as alternative couplers to silanes for fabricating dental composites. [ABSTRACT FROM AUTHOR]

A new ferrotitanate semiconductor NaFeTi 3 O 8 was developed by sol−gel citrate complexation synthesis. The sample preferentially developed into nanorods. The nanorods showed good XRD Rietveld refinements in the isostructure with Na 0.2 TiO 2 . The structure retains the two-dimensional layers of (Fe/Ti)O 6 octahedra and one-dimension channels in the structure. SEM, TEM, EDS, and specific surface area analysis were employed to characterize the samples. Results showed that the optical absorption of NaFeTi 3 O 8 nanorods is in the visible wavelength region. The direct allowed bandgap (2.12 eV) shows the characteristic charge-transfer transitions of O 2p/Fe 3d→(Ti/Fe) 3d. The d–d allowed transitions in the FeO 6 octahedron presented considerable contributions to the narrow bandgap. NaFeTi 3 O 8 exhibited potential as a photocatalyst for RhB photodegradation under visible light excitation ( λ  > 420 nm). Photocatalytic activities are discussed in relation to the structural properties. [ABSTRACT FROM AUTHOR]

Uranium(VI) has become one of the most potential contaminants due to its productive and irreversibility impact on the surrounding environment. Titanate nanowires (TNWs) have attracted significant attention because of its high ion exchange ability and facile synthesis. Herein the TNWs were synthesized, and the morphology and structure of TNWs were investigated by Fourier transformed infrared spectroscopy, scanning electron microscope, transmission electron microscope, X-ray diffraction and X-ray photoelectron spectroscopy in detail. The application of TNWs in U(VI) removal was studied under various environmental conditions using batch technique, and the results indicated that the sorption of U(VI) on TNWs was strongly affected by pH and weakly affected by ionic strength. The presence of PO 4 3- and CO 3 2- could overwhelmingly influence U(VI) interaction with TNWs, which was mainly attributed to the formation of anionic and electro-neutral complexes. From the Langmuir model simulation, the maximum sorption capacities were calculated to be 358, 384, and 410 mg g −1 at the temperatures of 298 K, 313 K and 328 K, respectively. The thermodynamic results revealed that the interaction process was spontaneous and endothermic. The extraordinary ion exchange capacity and facile synthesis under mild conditions made TNWs promising materials for the potential application in the efficient elimination of U(VI) or other lanthanides and actinides from aqueous solutions in the environmental radioactive pollution cleanup. [ABSTRACT FROM AUTHOR]

Using tetrabutyl titanate and thiourea as titanium and sulphur source, S-doped TiO2/palygorskite (S–TiO2–Pal) composites were prepared by a solgel method. The XRD patterns of S–TiO2–Pal photocatalysts exhibited the characteristic reflection at 2θvalues of 8.3° of Pal gradually disappear, while those of the quartz become more intense with the increase in calcination temperature (400–600 °C). The photocatalytic activity of composites was evaluated by photocatalytic degradation of Reactive Black KN-B (KN-B), which is exposed under UV light at the wavelength of 254 nm and visible light of 11 W. The results showed that when the mass ratio of S to TiO2was 1:3, calcination temperature 500 °C and pH value of dye solution 2.00, the photocatalytic degradation rate of S–TiO2–Pal catalyst under UV and visible lights increased significantly relative to that of TiO2, respectively. Furthermore, the photocatalytic kinetics could be well fitted with the classical first-order Langmuir–Hinshelwood model. [ABSTRACT FROM PUBLISHER]

The use of solar-driven photocatalysis for the degradation of recalcitrant organic waste from water is a promising and environmentally friendly technology to meet the challenge of mitigating increasing global pollution. This paper presents a new composite of layered H 2 Ti 3 O 7 hydrothermal nanotubes (TNT) with cadmium telluride quantum dots prepared by the simple mixing suspensions of both components in TNT/CdTe-QDs ratios in the range of 1:0.005–1:0.03. The products were characterized by X-ray diffraction, spectroscopic techniques such as Fourier transform infrared, Raman scattering, UV–visible diffuse reflectance, photoluminescence, and X-ray photoelectron spectroscopy, as well as by scanning and transmission electron microscopy. The photocatalytic performance of the products was tested by photocatalytic degradation of two molecular models of contaminants, methyl orange (MO) and 4-chlorophenol (4-CP). Nearly 100 % removal of organic contaminants was achieved and the degradation rate of MO and 4-CP under simulated sunlight in the presence of QDs was approximately five and four times faster than using TNT alone, respectively. The degradation rate response in the presence of specific radical scavengers corresponds to a direct Z-scheme photocatalysis. Recycling experiments demonstrated a structurally stable catalyst that maintains its efficiency after five irradiation cycles. Photoelectrochemical and photocurrent measurements validated the synergistic effect observed, reflecting that heterojunction promotes the transfer of photogenerated electrons and holes, decreasing recombination changes and improving photocatalytic activity. [Display omitted] [ABSTRACT FROM AUTHOR]

Hydrothermally synthesized one dimensional trititanate nanotubes (TNT) were characterized by using TEM, XRD, Raman, FTIR, TGA and BET surface area analysis to explore their morphology, structure and surface properties. Transmission electron microscopy (TEM) measurements showed the hollow tubular structure of TNT with inner diameter of 3–4 nm and outer diameter of 8–12 nm. The surface area of TNT, obtained from BET analysis was 282 m 2 /g , which was about 56 fold higher than that of the anatase TiO 2 fine particle (5.1 m 2 /g). The fluoride uptake capacity of the adsorbent was estimated through batch adsorption experiments. The kinetics data revealed that the most of the adsorption took place in the first 10 min and adsorption equilibrium was reached within 2 h, following a pseudo second order model. The defluoridation capacity of TNT decreased significantly with the increase of pH from 2 to 12. This is in accordance with the measured iso-electric point (IEP) of TNT which was estimated to be 2.5. Fourier transforms infrared (FTIR) analysis indicated that the fluoride was adsorbed by TNT via hydroxyl ion-exchange mechanism. The adsorption isotherms complied was in consonance with the Langmuir model. Calculated R L values were indicative of the favorable use of TNT to treat higher fluoride concentrated water. The maximum fluoride adsorption capacity of TNT was estimated to be 58 mg/g. TNT exhibited an excellent adsorption capacity for fluoride when compared to commercial TiO 2 nanoparticles and other nanomaterials reported in literature. Layered crystal structure, large surface area, protonated surface and readily available hydroxyl ions of TNT adsorbent are responsible factors for efficient fluoride adsorption. [ABSTRACT FROM AUTHOR]

In this work, bismuth sodium titanate (BNT) and cerium (Ce)-doped BNTwere successfully synthesized using the soft combustion method. The effect of 3, 5, and 7 mol% Ce, respectively added as dopant on stoichiometry, microstructure, density and dielectric properties were studied. Pure BNT phase was obtained in the sample containing 3 mol% Ce after calcination at 800 °C for 3 h. The calcined powders were then pressed into pellets and sintered at 1100 °C for 3 h. The grain size of the pellets decreased with the addition of Ce 3+ because Ce acted as a grain growth inhibitor. Maximum density was obtained in 3 mol% Ce-doped BNT, and decreased with increasing amount of Ce dopant. In addition, the maximum dielectric constant of 468.35 was obtained in 3 mol% Ce-doped BNT and decreased at higher amount of Ce doping. The addition of Ce as a dopant in BNT also decreased the dielectric loss. [ABSTRACT FROM AUTHOR]

A new method for predicting the adsorption capacity of pure hydrogen titanate (H 2 Ti 3 O 7 ) nanotubes (HTN) via one-step dye-removal method of chemically-activated catalytic process conducted in the dark has been recently demonstrated. In this work, hydrogen phosphate anions (HPO 4 2− ) modified H 2 Ti 3 O 7 nanotubes (HP-HTN) have been synthesized via the hydrothermal treatment of sol–gel derived titanyl phosphate (TiP 2 O 7 )/phosphate (PO 4 3− ) ions modified nanocrystalline anatase-titania (TiO 2 ). The methylene blue (MB) adsorption capacity of HP-HTN has been determined to be 139 mg g −1 which is higher than that (105–121 mg g −1 ) of pure HTN. It has been demonstrated that HP-HTN can decompose the MB dye in an aqueous solution via the hydrogen peroxide (H 2 O 2 ) activation. It is observed that the HP-HTN exhibit higher dye-decomposition rate-capacity compared with that of pure-HTN. The maximum MB dye-removal rate-capacity of 194 and 393 mg g −1 h −1 has been determined at the initial H 2 O 2 concentration of 3 and 15 wt%. The HP-HTN exhibit a perfect liner relationship (slope and regression correlation coefficient, < r 2 >, values of 17 mg g −1 h −1 wt% −1 and 0.999) between the maximum MB dye-removal rate-capacity as a function of initial H 2 O 2 concentration which strongly supports the new method for the prediction of adsorption capacity via the one-step dye-removal method of chemically-activated catalytic process conducted in the dark. [ABSTRACT FROM AUTHOR]

The synergistic effect of Cu(II) adsorption on the enhanced photodegradation of bisphenol A (BPA) by TiO 2 /titanate nanotube (TNTs) was investigated under UV light irradiation. TNTs were fabricated by hydrothermal method and calcined at 500 °C for 4 h (TNT-500) to adsorb Cu(II) as well as to increase the photocatalytic activity. The TNT-500 exhibited an excellent adsorption ability on copper ions and the adsorption isotherm of Cu(II) followed the Langmuir model with the maximum adsorption capacity of 54 mg/g at pH 5. In addition, the photocatalytic activity of TNT-500 toward BPA degradation was significantly enhanced by factors of 20–34 after the adsorption of 5–40 mg/g Cu(II). The pseudo-first-order rate constant ( k obs ) for BPA photodegradation was highly dependent on Cu(II) concentration and an optimized value of 20 mg/L was obtained. The reaction rate of BPA by optimized Cu-loaded TNT-500 was 5.2 times higher than that of P25 TiO 2 . In addition, the photocatalytic activity of Cu-loaded TNT-500 was significantly enhanced at pH > 4.8 and can be recycled for at least 5 times to completely photodegrade BPA under 365 nm UV light irradiation. Results obtained in this study clearly indicate that TNTs are promising nanomaterials for coupled removal of Cu(II) and BPA in aqueous solutions which can open an avenue to develop an effective strategy for removal of mixed contaminants in water and wastewater treatment. [ABSTRACT FROM AUTHOR]

Copyright of Science of Sintering is the property of National Library of Serbia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Microwave annealing was employed to prepare well defined titanate nanotubes after hydrothermal treatment of titania precursor at mild conditions. The microwave annealed samples were used for the enhancement of UV-light-driven photocatalysis capabilities of Rose Bengal from liquid phase. The structural and catalytic activity changes were studied as a function of microwave annealing temperature. Different characterization techniques such as thermal and spectroscopic techniques were employed to characterize the as-prepared and microwave annealed samples. Characterizations confirmed the formation of hollow layered titanate nanotubes with diameter of ≈11–13 nm and several millimeter in length in the as prepared samples. Titanate was the main structure of the prepared hollow nanotubes. These nanotubes undergo a partial collapse after elevating the microwave temperature to 450–550 °C. Moreover, all the nanotubes were converted to nanoparticles after 600 °C with particle size ranged between 9 and 16 nm. The prepared samples showed significant catalytic performance in the photo oxidation of Rose Bengal (probe reaction) under UV irradiation. Moreover, the sample heated at 300 °C presented the highest catalytic activity among the prepared samples. [ABSTRACT FROM AUTHOR]

Aims To evaluate the effect of the processing method (conventional sintering, S, and heat-pressing, HP) and addition of potassium titanate fibers, PTF, on the microstructure, mechanical properties (flexural strength, σ f , and Weibull parameters, m and σ 5% ), slow crack growth parameters n (stress corrosion susceptibility coefficient), and optical properties (translucency parameter, TP, and opalescence index, OI) of a feldsphatic dental porcelain. Methods Disks ( n =240, Ø12×1 mm) of porcelain (Vintage-Halo, Shofu) were produced using S and HP methods with and without addition of 10 wt% (conventional sintering) or 5 wt% (heat-pressing) of PTF. For the S method, porcelain was sintered in a conventional furnace. In the HP technique, refractory molds were produced by lost wax technique. The porcelain slurry was dry-pressed (3 t/30 s) to form a cylinder with 12 mm (diameter) and 20 mm (height), which was heat-pressed for 5 min/3.5 bar into the mold. Specimens were tested for biaxial flexural strength in artificial saliva at 37 °C. Weibull analysis was used to determine m and σ 5% . Slow crack growth (SCG) parameters were determined by the dynamic fatigue test, and specimens were tested in biaxial flexure at five stress rates: 10 −2 , 10 −1 , 10 0 , 10 1 and 10 2 MPa/s ( n =10), immersed in artificial saliva at 37 °C. Parameter n was calculated and statistically analyzed according to ASTM F394-78. Optical properties were determined in a spectrophotometer in the diffuse reflectance mode. Results The highest n value was obtained by the combination of heat-pressing with fiber addition (37.1) and this value was significantly higher than those obtained by both sintered groups (26.2 for control group and 27.7 for sintered with fiber). Although heat-pressing alone also resulted in higher n values compared to the sintered groups, there were no significant differences among them. Fiber addition had no effect on mechanical strength, but it resulted in decreased TP values and increased OI values for both processing methods. Heat-pressing alone was able to reduce the porosity level of the porcelain. Conclusions Addition of PTF combined with heat-pressing can reduce strength degradation of a dental porcelain compared to sintered materials with or without fibers. Heat-pressing (HP) alone should be considered as a good alternative for clinical cases where high translucency is required. [ABSTRACT FROM AUTHOR]