Presence Of Zirconium Research Articles

Preparation and characterization of a poly(methyloctadecylsiloxane) thermally immobilized onto zirconized silica stationary phase for high-performance liquid chromatography

This study describes the preparation and characterization of a HPLC stationary phase (SP) obtained by deposition of poly(methyloctadecylsiloxane) (PMODS) onto the surface of porous zirconized silica particles, followed by thermal immobilization. The SP were characterized using elemental analysis and infrared and 29Si NMR spectroscopies, while their chromatographic behaviors were investigated by separation of selected neutral, acidic and basic compounds of different test mixtures (Engelhardt, SRM 870 and Tanaka tests). The preparation of the metalized support and the thermal immobilization of PMODS onto zirconized silica, optimized by experimental design, produced a SP based on PMODS that showed high values of efficiency (up to 85000plates/m) and appropriate asymmetry factors. The presence of zirconium on the surface significantly decreases silica solubility in severe conditions (alkaline mobile phase at pH 10 and high temperature), increasing column lifetime.

Synthesis of functionalized polymeric adsorbent selective to cobalt

AbstractAmino derivative of chloromethylated polystyrene resin was synthesized and functionalized by 1,10‐phenanthroline (1,10‐Phen) to yield a novel adsorbent, namely 4‐methylamino‐[N,N‐bis(2,2′)‐1,10‐phenanthroline] polystyrene (4‐MABPPS). The complete development of novel adsorbent along with its characterization is described in detail. The adsorption ability and selectivity of 4‐MABPPS were investigated for cobalt and zirconium ions so as to efficiently separate cobalt ion impurities from zircalloy cladding material of nuclear reactors. The experimental results showed selective uptake of cobalt by the adsorbent in the presence of zirconium. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Chitosan scaffolds containing silicon dioxide and zirconia nano particles for bone tissue engineering

A scaffold harboring the desired features such as biodegradation, biocompatibility, porous structure could serve as template for bone tissue engineering. In the present study, chitosan (CS), nano-scaled silicon dioxide (Si) and zirconia (Zr) were combined by freeze drying technique to fabricate a bio-composite scaffold. The bio-composite scaffold (CS/Si/Zr) was characterized by SEM, XRD and FT-IR studies. The scaffold possessed a porous nature with pore dimensions suitable for cell infiltration and colonization. The presence of zirconia in the CS/Si/Zr scaffold decreased swelling and increased biodegradation, protein adsorption and bio-mineralization properties. The CS/Si/Zr scaffold was also found to be non-toxic to rat osteoprogenitor cells. Thus, we suggest that CS/Si/Zr bio-composite scaffold is a potential candidate to be used for bone tissue engineering.

Combustion synthesis, characterization and catalytic application of MoO 3–ZrO 2 nanocomposite oxide towards one pot synthesis of octahydroquinazolinones

Pure ZrO 2 and MoO 3 (10 mol%)-ZrO 2 nanocomposite oxides were prepared by solution combustion method using glycine as fuel. The synthesized materials were characterized by X-ray diffraction (XRD), Scanning Electron microscopy (SEM), Transmission electron microscopy (TEM) and UV–vis spectroscopic technique. XRD study revealed selective stabilization of the tetragonal phase of zirconia in presence of MoO 3. The crystallite size was calculated from the Fourier line shape analysis of the broadened X-ray diffraction profiles as well as from TEM measurements. Oxide nanoparticles with size in the range of 5–40 nm was observed depending upon the fuel content in the combustion mixture. UV–vis study indicated well dispersion of the molybdenum oxide component in the zirconia matrix in the form of isolated and cluster molybdates. The MoO 3–ZrO 2 nanocomposite oxide was used as an efficient and environmentally benign catalyst for the synthesis of octahydroquinazolinones by multicomponent condensation reaction of dimedone, urea and arylaldehydes in aqueous media as well as under solvent free condition using microwave irradiation. A series of zirconia based heterogeneous catalyst with different acidity and surface area were screened for this reaction. The MoO 3 (10 mol%)-ZrO 2 catalyst was found to be highly active for the transformation with excellent yield and purity of the product in a short reaction time.

Preparation and characterization of zirconia and mixed zirconia/titania in ionic liquids

Zirconia and mixed zirconia/titania were synthesized in two different ionic liquids, namely, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) amide ([BMP]TFSA) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) amide ([EMIm]TFSA) using sol–gel methods. The synthesized oxides were characterized by means of X-ray diffraction, scanning electron microscopy with energy dispersive X-ray (SEM-EDX)), thermogravimetric and differential thermal analyses (TGA–DTA). The results show that the as-synthesized ZrO2 powders obtained either in [BMP]TFSA or in [EMIm]TFSA show amorphous behaviour, and calcination at 500 °C yields t-ZrO2 which is subject to further phase transformation to m-ZrO2 at 1000 °C. The type of the ionic liquid influences the morphology of the synthesized zirconia as the sample obtained from [BMP]TFSA showed a porous morphology with very fine particles in the nanometer regime, whereas micro-rods were obtained from [EMIm]TFSA. ZrO2-TiO2 nanorods with an average diameter of about 100 nm were synthesized in [EMIm]TFSA. The presence of zirconia in the mixed oxides stabilizes the anatase phase and elevates the temperature at which the phase transformation to rutile occurs.

Effect of zirconium on the concentration of tributyl phosphate in the aqueous phase of the H2O-HNO3-Zr-TBP extraction system

The concentration of tributyl phosphate (TBP) in an aqueous phase containing various amounts of HNO3 and zirconium after contact with 70% TBP in RED-3 was determined. It was found that the presence of nitric acid resulted in a decrease in the solubility of TBP in the aqueous phase, whereas the presence of zirconium facilitated the solubility of TBP. Upon the precipitation of zirconium hydroxide from the aqueous phase with ammonia, a portion of TBP was sorbed by the precipitate. To decrease the trapping of TBP, zirconium hydroxide should be precipitated with a solution of NaOH at pH 8. The TBP dissolved in the aqueous phase can be removed by repeatedly washing with the diluent.

Microstructural and densification study of natural Indian magnesite in presence of zirconia additive

The sintering and microstructural evaluation of Indian magnesite was carried out in presence of zirconia. Zirconia in monoclinic form was added in the range 3–6 wt% with respect to raw magnesite and the sintering temperature selected were 1500–1600°C for 2 h. The main impurities present in the magnesite were Fe2O3, CaO, SiO2. The natural crystalline magnesite could be sintered with bulk density of 3.38 g/cc (A.P. 1.54%) at 1550°C/2 h. But the higher bulk density (3.50 g/cc) and minimum apparent porosity (A.P. 0.25%) was attained at 1550°C/2 h with the 3 wt% zirconia additive. On firing magnesite with zirconia as additive, a crystalline phase, magnesio-zirconate, was identified at the triple point regions of the direct bonded periclase grains. The morphology of the periclase grains were changed from subrounded/rounded to angular shaped in presence of zirconia as additive.

Regioselective intermolecular cycloalumination of cyclic allenes and ethylene with R n AlCl3−n , catalyzed by titanium and zirconium complexes

Intermolecular cycloalumiation of cyclic 1,2-dienes and ethylene with organoaluminum compounds R n AlCl3−n in the presence of zirconium- and titanium-based catalysts occurred regioselectively with formation of unsaturated bicyclic organoaluminum compounds in high yields.

10.1007/s11445-008-2018-y

Single crystals of the solid solutions RbTi1 − x Zr x OPO4 (0.015 < x < 0.034) were grown and their physical properties were studied. In the presence of zirconium in the crystals with the maximum content x = 0.034, the ferroelectric phase transition and the high-temperature transition from the orthorhombic to the cubic phase are shifted to lower temperatures by 100 and 50°C, respectively. In the temperature range from 700°C to room temperature, the conductivity of doped crystals decreases compared to that of the undoped crystals. It is of particular interest that the intensity of the second-harmonic generation of the doped crystals is substantially higher than that of RbTiOPO4.

Influence of Nanoparticles on the Rheological Behaviour and Initial Stages of Crystal Growth in Linear Polyethylene

AbstractWe demonstrate the role of broad molecular weight distribution (MWD) polyethylene (PE), in the presence of nanoparticles of different aspect ratios and binding efficiency with the polymer, in the formation of shish‐kebab structures under a shear protocol using time‐resolved small‐angle X‐ray scattering (SAXS). The results indicate a scattered intensity in the form of streaks at the equator while maxima in the meridian confirm the presence of an oriented structure in the polymer. The SAXS facilitated the probing of the steady growth of the obtained shish‐kebab structures at an isothermal crystallization temperature (136 °C). The study reveals the influence of nanoparticles (single walled carbon nanotubes (SWNTs) and zirconia) in chain orientation. The presence of nanoparticles promotes the high degree of orientation, where shish is formed along the flow direction and kebab perpendicular to it. A higher degree of chain orientation is observed in the presence of SWNTs compared to zirconia nanoparticles. The SWNTs present in a small concentration (&lt; 0.6 wt.‐%) are aligned in the flow direction, which leads to an increase in shish length as estimated from Ruland's streak analysis. The stable shishes in the early stages of crystallization suppress the nucleation barrier for further crystallization. Compared to the polymer without nanoparticles the shish length increases in the presence of zirconia, however, the increase in shish length is much more pronounced in the presence of SWNTs compared to zirconia nanoparticles. The nanoparticles favor the orientation fraction as deduced from the integrated intensity of scattering at the equator and meridian in the patterns. Absence of a plateau in the low frequency region of the polymer–SWNT composites suggests the non‐existence of network formation. Nevertheless, comparing the storage modulus at two different temperatures (142 and 160 °C), suggests a strong temperature dependence and difference in adsorption energy of the two nanoparticles.magnified image

Characterization of precipitate evolution in an artificially aged Al–Zn–Mg–Sc–Zr alloy

The precipitates of an age-hardenable Al–Zn–Mg–Sc–Zr alloy aged at 140°C have been studied by transmission electron microscopy (TEM). The results are interpreted in terms of structural transformations that involve two types of Guinier-Preston (GP) zones (I and II), the metastable η′ hardening precipitate and the stable phase η-phase (MgZn2). At early stages of ageing, the GPI zones act as nucleation sites for the plate-like η′ phase which precipitates on the {111}Al plane. The transformation from η′ to η occurs gradually at longer ageing times. The η particles mainly consist of η1 and η2 phase, with small amounts of η4 type and minor quantities of η′ type structures. Furthermore, while a fine dispersion of coherent Al3(Sc,Zr) precipitates is known to have a beneficial effect on the strengthening of the alloy, the formation of GPII zones is suppressed in the presence of zirconium that leads to a reduction in the amount of η′ formed during subsequent ageing.

Thermally grown oxide scales on γ-TiAl coated with thermal protection systems

Thermal barrier coatings (TBCs) of yttria partially stabilized zirconia were deposited on gamma TiAl samples using electron-beam physical vapour deposition. The specimens were coated with intermetallic Ti –Al – Cr layers and CrAlYN/CrN nanoscale multilayer coatings. The lifetime of the TBC systems was determined performing cyclic oxidation tests in air at temperatures between 850 and 950–C. The TBC systems with Ti –Al – Cr and CrAlYN/CrN layers did not fail at 850 and 900–C during the maximum exposure time period of 1000 cycles of 1 h dwell time at high temperature. No spallation of the thermal barrier coatings was observed. As revealed by post-oxidation microstructural analysis, the protective coatings were severely degraded when exposed at 900–C, resulting in growth of mixed oxides on the substrate. Underneath the thermal barrier coating an outer oxide scale with a columnar structure was observed, consisting of rutile and α-Al2O3. Energy-dispersive X-ray spectroscopy analysis revealed zirconia and chromia being dissolved in the outer oxide scale. The columnar structure and the presence of zirconia indicated an effect of the TBC on the morphology of the outer oxide scale. The zirconia top coat exhibited an excellent adherence to this oxide scale formed on the protective layers when degraded, and at defects like cracks. When thermally cycled at 950–C, the TBC system on specimens coated with Ti –Al – Cr failed by spallation of the thermally grown mixed oxides, whereas the thermal barrier coating was well adherent to the outer oxide scale at this temperature, too.

Solubility of ThO 2 in Gd 2Zr 2O 7 pyrochlore: XRD, SEM and Raman spectroscopic studies

Solubility of ThO 2 in gadolinium zirconate pyrochlore, a potential host for radioactive materials, has been investigated. The phase relations in Gd 2− x Th x Zr 2O 7+ x /2 (0.0 ⩽ x ⩽ 2.0) systems have been established under the slow-cooled conditions from 1400 °C. XRD studies reveal that the compositions corresponding to x = 0.0–0.075 are single phasic in nature and beyond x ⩾ 0.1 the biphasic region starts. The first biphasic region comprising of pyrochlore and thoria exist from x = 0.1–0.8, and from x = 1.2 another biphasic region consisting of gadolinia stabilized zirconia (GSZ) and thoria appears which persists till x = 1.6. The end member (i.e. x = 2.0) of the series is found to be a mixture of monoclinic ZrO 2 and thoria. Interestingly, gadolinia which has wide solubility in thoria, did not show any miscibility in thoria in the presence of zirconia. Irregular grains of Gd 1.8Th 0.2Zr 2O 7.1 as shown in SEM supports its biphasic nature. Raman spectra of heavily thoria doped ( x = 0.1 and 0.2) samples, indicates the presence of Zr–O 7 mode which implies the samples are highly disordered in nature.

Characterisation of fume from hyperbaric welding operations

We report preliminary work characterising dust from hyperbaric welding trials carried out at increased pressure in a helium and oxygen atmosphere. Particle size and concentration were measured during welding. Samples for quartz and metal analysis and toxicity assessment were taken from a filter in the local fume extraction system. The residue of dust after metal extraction by nitric acid in hydrogen peroxide predominantly a non-metallic white powder assumed to be dust from welding rod coatings and thermal insulation material. Metallic analysis showed predominantly calcium, from the welding rod coating, and period 4 transition metals such as iron, manganese, magnesium and titanium (inductively coupled mass spectrometry, Agilent 7500c). The presence of zirconium indicated a contribution from grinding. The fume was nanoparticulate in nature with a mean particle diameter of 20-30 nm (MSI Inc WPS 1000XP). It showed an intermediate level of oxidative potential regarding the low-molecular weight respiratory tract lining fluid antioxidants ascorbate and glutathione and caused release of the inflammatory marker IL-8 in a human lung A 549 epithelial cell culture with no indication of cytotoxicity. The study findings have strong implications for the measurement techniques needed to assess fume exposure in hyperbaric welding and the provision of respiratory protection.

Incorporation of zirconia into coatings formed by DC plasma electrolytic oxidation of aluminium in nanoparticle suspensions

A study has been carried out to investigate the incorporation of zirconia into alumina-based coatings formed on aluminium using DC plasma electrolytic oxidation in phosphate and silicate electrolytes containing zirconia nanoparticles in suspension. The nanoparticles were incorporated mainly near the coating surface and within cavities inside the coatings. Additionally, a silicon-rich, surface deposit appeared to entrain the nanoparticles of the silicate electrolyte. Zirconia was also present in cellular microstructures of the main alumina-rich coating layers, suggesting melting at >1710 °C and subsequent solidification. The coatings frequently contained tetragonal zirconia in addition to monoclinic zirconia, with the presence of zirconia also affecting the proportions of γ- and α-alumina in favour of the former phase.

Método de impregnação química aplicado em tubos microporosos e membranas tubulares para a microfiltração de emulsões e suspensões de bactérias

Uma técnica de impregnação química via solução de precursor foi desenvolvida para formação de filmes finos em tubos microporosos e membranas tubulares. O desempenho desta técnica foi analisado no processo de microfiltração de emulsões (óleo vegetal/água) e de suspensões de bactérias (Escherichia coli) do soro residual do processamento de queijo. Os tubos microporosos (tamanho nominal 0,5 µm) foram impregnados com solução precursora de zircônia (e calcinados a 600 e 900 ºC) afim de influenciar na melhora do processo de desemulsificação e as membranas cerâmicas (tamanho nominal entre 0,8 µm e 1,2 µm) foram impregnadas com precursor (e calcinadas a 600 °C) para formação de prata metálica, para agir como bactericida na suspensão residuária de bactérias da indústria de queijo. O meio poroso impregnado foi caracterizado por meio de microscopia eletrônica de varredura. Os resultados da análise do permeado para valores do teor orgânico de carbono são respectivos ao tratamento de emulsões; o valor da contagem de bactérias via análise de plaqueamento é respectivo ao tratamento de suspensão de bactérias. Os resultados foram analisados e discutidos em função do desempenho e da influência da impregnação quanto à presença de zircônia ou prata para cada aplicação.

Synthesis and properties of zirconium-doped RbTiOPO4 single crystals

Single crystals of the solid solutions RbTi1 − x Zr x OPO4 (0.015 < x < 0.034) were grown and their physical properties were studied. In the presence of zirconium in the crystals with the maximum content x = 0.034, the ferroelectric phase transition and the high-temperature transition from the orthorhombic to the cubic phase are shifted to lower temperatures by 100 and 50°C, respectively. In the temperature range from 700°C to room temperature, the conductivity of doped crystals decreases compared to that of the undoped crystals. It is of particular interest that the intensity of the second-harmonic generation of the doped crystals is substantially higher than that of RbTiOPO4.

An Expedient One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-Ones and -Thiones Catalyzed by ZIRCONIA Nanopowder. An Improved Protocol for the Biginelli Cyclocondensation Compounds in &amp;#x2018;Dry Media&amp;#x2019;

A general and practical Green Chemistry route to the Biginelli cyclocondensation multicomponent reaction had been carried out by the three-component coupling of β-ketoesters, various structurally diverse aldehydes including heterocyclic aldehydes and urea/thiourea in the presence of Zirconia (ZrO2) nanopowder catalyst in dry media under microwave irradiation and a comparative study was also done under thermal conditions giving 3,4-dihydropyrimidin-2(1H)-ones and -thiones (DHPMs) in excellent yields. Besides, it was highlighted that ZrO2 nanopowder can be reused up to six times after simple washing with ethyl acetate, thus exposing the process economical and environmentally benign. Keywords: Cyclocondensation multicomponent reaction, biginelli compounds, 3,4-dihydropyrimidin-2(1H)-ones and, –, thiones, ZrO2 nanopowder, environmentally benign, dry media

Inhibition of mineralization by a calcium zirconium phosphate coating

Bioactive ceramics used as coating materials combine the conductive properties of a bioceramic with the mechanical stability of the metal implant. We studied a calcium zirconium phosphate-containing coating material, FA-CZP [Ca(5)(PO(4))(3)F, CaZr(4)(PO(4))(6)], that is relatively insoluble in the biological milieu. The reaction of bone to this material was investigated histologically and histomorphometrically in an animal trial. Cylindrical Ti6Al4V specimens that had been coated with FA-CZP by plasma spraying were implanted in the femoral condyles of rabbits. The implants were left in place for 2, 4, 6, 12, and 14 weeks. FA-CZP led to impaired mineralization of the newly formed bone at the interface. Noncalcified osteoid was found throughout the whole study period. The layer seemed to become thicker with time. The mineralization disorder is evidently caused by zirconium ions. The presence of zirconium in the osteoid in contact with the implant was demonstrated by means of two different staining methods.

Corrosion Behavior of the Electrochemical Couple: Hastelloy/Carbon Material in Zirconium Fluoride - Sodium Fluoride Melts

Time dependencies for the parameters (current, voltage, inner resistance) of short-circuited galvanic cell: Hastelloy-carbon material have been studied in NaF-ZrF4 eutectic melt at 600- 650oC. Analysis of these data, together with the data on polarization of separate electrodes at open circuit conditions, showed that short-circuit current is related to the rate of corrosion of the alloy contacted with carbon. In the presence of zirconium, the short-circuit current corresponds to the rate of zirconium interaction with the fluoride melt and can be used for studies of its dissolution kinetics. It was found that contact of Hastelloy with carbon material results in an increase of corrosion rate both in pure NaF-ZrF4 eutectic melt and with the additives of LaF3. The presence of zirconium in fluoride melt suppresses the corrosion process.