Presence Of Hydrofluoric Acid Research Articles

Synthesis of Ti-Ni and Zr-Ni Core–Shell Particles Using Galvanic Replacement

This article focuses on the galvanic replacement synthesis of Ti-Ni and Zr-Ni metal systems with a “core-shell” structure, which are potential precursors for intermetallics. The authors defined effective synthesis parameters and formation features of polymetallic systems characterized by granulometric, phase, and elemental composition. X-ray fluorescence and X-ray phase analysis methods showed that the deposition of nickel on dispersed titanium and zirconium leads to the production of test samples with phase composition representing a mechanical mixture of Ni and Ti, and Ni and Zr. The method of X-ray fluorescence analysis showed that the presence of hydrofluoric acid with a 0.5-1.5 M concentration results in the formation of fixed quantitative ratios of elements in the precipitate, which allows the quantitative composition of dispersed systems “titanium-nickel” and “zirconium-nickel” to be regulated within a relatively wide range. Scanning electron microscopy proved that all synthesized systems are characterized by a highly porous structure that follows the titanium and zirconium particle surface contour and the presence of spherical nanoscale subunits on the formed particle surface.

Acute Rubigine® Poisoning in Martinique a French Overseas Department of America: Clinical Characteristics and Prognostic Factors.

Rubigine® is an anti-rust stain remover containing fluorides which is believed to have been the cause of many deaths in Martinique. However, after the modification of its composition in 2006, serious poisoning from old formulas containing fluorides persisted. Our main objective was to determine the clinical characteristics and prognostic factors of these intoxications. Methods: Any patient admitted to the Martinique University Hospital for acute Rubigine® poisoning was included from 1 January 2000 to 31 December 2016. Usual demographic and clinical data were collected and comparisons between surviving and deceased patients made using a univariate analysis and logistic regression. Results: Fifty-five patients were included (mean age: 43 years; sex ratio M/F: 1.1), and the main clinical characteristics were: changes in electrocardiogram (ECG) (80%), digestive system disorders (75%), and neurological disorders (12%). The main features linked to death were the presence of hydrofluoric acid (p < 0.0001), age over 55 years (p = 0.01), hypocalcemia after the initial intravenous calcium supplementation (p = 0.0003), diarrhea (p < 0.0001), hypersialorrhea (p < 0.0001), myocardial excitability (p < 0.0001), and state of shock (p < 0.0001). Three patients required circulatory support by venous-arterial ECMO. Mortality was 10.9%. Conclusions: Rubigine® poisoning is responsible for significant morbidity and mortality. Fortunately, its incidence as well as mortality has sharply decreased in Martinique thanks to the measures taken by the French state. This retrospective work nevertheless shows that acute intoxication by the old formula of Rubigine® remains the main factor of poor prognosis.

Some transformations of tetrahydropyrimidines

An efficient synthesis method based on three-component condensation of various aldehydes, methylene active compounds and phenylthiourea (urea) in the presence of hydrofluoric acid has been developed and some of their transformations have been carried out. An efficient method has been developed for the synthesis of some derivatives of tetrahydropyrimidine-5-carboxylates based on the three-component condensation of various aldehydes and β-diketones with thiocarbamide. The antioxidant properties of the synthesized compounds were studied in model reactions by the kinetic method.

Influence of Two-Stage Anodization on Properties of the Oxide Coatings on the Ti–13Nb–13Zr Alloy

The increasing demand for titanium and its alloys used for implants results in the need for innovative surface treatments that may both increase corrosion resistance and biocompatibility and demonstrate antibacterial protection at no cytotoxicity. The purpose of this research was to characterize the effect of two-stage anodization—performed for 30 min in phosphoric acid—in the presence of hydrofluoric acid in the second stage. Scanning electron microscopy, atomic force microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Raman spectroscopy, glow discharge optical emission spectroscopy, nanoindentation and nano-scratch tests, potentiodynamic corrosion studies, and water contact angle measurements were performed to characterize microstructure, mechanical, chemical and physical properties. The biologic examinations were carried out to determine the cytotoxicity and antibacterial effects of oxide coatings. The research results demonstrate that two-stage oxidation affects several features and, in particular, improves mechanical and chemical behavior. The processes influencing the formation and properties of the oxide coating are discussed.

Effect of polyethylene glycol on crystal growth and photocatalytic activity of anatase TiO2 single crystals.

In order to evaluate the effect of polyethylene glycol (PEG) on the growth of TiO2 crystals, anatase TiO2 crystals with different morphologies and structures were synthesized by controlling the content and type of PEG in a solvothermal system. Then, their morphology and structure were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Characterization results show that hydrofluoric acid can promote the formation of high activity (001) facets. Experiments on the effect of PEG on crystal growth show that the low molecular weight PEG (PEG400) can accelerate crystal differentiation and relieve the agglomeration of crystals in the presence of hydrofluoric acid. Besides, according to the experimental results, we found that PEG400 can reduce the agglomeration size and number of TiO2 polycrystalline particles. Research on the photocatalytic activity proposed that the independence of single crystal and the integrity of (001) facets are the critical factors in advanced oxidation reaction. The resultant anatase TiO2 single crystals could produce more hydroxyl radicals (˙OH) in the photocatalytic system, which exhibited remarkable photocatalytic performance for the degradation of Acid Red B.

Комплексы меди [CuBr2(DMSO-O)3] и [Cu(DMSO-O)4SF6]. Синтез и строение

The dissolution of copper (II) bromide and copper (II) fluoride in the presence of hydrofluoric acid in dimethyl sulfoxide, followed by slow evaporation of the solvent, have synthesized copper complexes [CuBr 2 (DMSO- O ) 3 ] ( 1 ) and [Cu(DMSO- O ) 4 SF 6 ] ( 2 ). They have been structurally characterized. The X-ray diffraction pattern has been obtained at 293 K on an automatic diffractometer D8 Quest Bruker (Mo K α -radiation, λ = 0.71073 Å, graphite monochromator) of crystals 1 [C 6 H 18 O 3 S 3 Br 2 Cu, M 457,74, the monoclinic syngony, the symmetry group P 2 1 /c; cell parameters: a 8.812(6), b 15.335(11), c 12.272(8) Å, α = 90.00 degrees, β = 105.82(3) degrees, γ = 90,00 degrees; V = 1595.5(19)Å 3 ; the crystal size is 0.59 × 0.32 × 0,24 mm; intervals of reflection indexes are –13 ≤ h ≤ 11, –23 ≤ k ≤ 23, –18 ≤ l ≤ 18; total reflections 45529; independent reflections 5832; R int 0.0971; GOOF 1.001; R 1 = 0.0497, wR 2 = 0.1073; residual electron density 0.77/–1.36 e/Å 3 ] and 2 [C 8 H 24 O 4 F 6 S 5 Cu, M 522.11, the triclinic syngony, the symmetry group P –1; cell parameters: a 10.325(18), b 10.428(18), c 10.60(2) Å, α = 77.93(11) degrees, β = 89.49(9) degrees, γ = 68.12(6) degrees; V = 1033(3) Å 3 ; the crystal size is 0.47×0.16×0.13 mm; intervals of reflection indexes are –11 ≤ h ≤ 11, –12 ≤ k ≤ 12, –12 ≤ l ≤ 12; total reflections 9324; independent reflections 3307; R int 0.0709; GOOF 1.029; R 1 = 0.0555, wR 2 = 0.1309; residual electron density 0.64/–0.82 e/Å 3 ], the copper atoms have a distorted square-pyramidal coordination (the trans -OCuO and trans -OCuBr angles are 165.68(11)° and 143.37(10)° ( 1 ); trans -OCuO are 163.8(2), 169.0(2)° ( 2 ); the Cu-Br and Cu-O bond lengths are 2.4681(14) Å and 2.5922(14) Å ( 1 ), 1.944(3)–2.054(3) Å ( 1 ) and 1.940(6)–1.956(5) Å ( 2 ) respectively). Fragment SF 6 in 2 (the FSF trans -angles 178.8(2)–179.7(3)°, cis -angles 88.7(2)–91.0(3)°) linked to the central copper atom (the Cu–F bond length 2.208(6) Å). The structural organization of crystals 1 and 2 is controlled by intermolecular bonds O (DMSO) ∙∙∙H–С (DMSO) (2,57 Å) and Cu–Br∙∙∙H–C (DMSO) (2.89–3.04 Å) ( 1 ), S–F∙∙∙H–C (DMSO) (2.32–2.60 Å) ( 2 ). Complete tables of coordinates of atoms, bond lengths and valence angles for structures 1 and 2 are deposited at the Cambridge Structural Data Bank (no. 1883471, 1898916; deposit@ccdc.cam.ac.uk; https://www.ccdc.cam.ac.uk).

In‐situ synthesis of silver nanoparticles on porous silicon nanostructure through galvanic displacement reaction and its application in construction of glucose screen printed sensor

In this work, a new nanocomposite as silver nanoparticles (AgNPs)@ porous silicon (PSi) was synthesised through a simple galvanic displacement reaction between silver ions and silicon in the presence of hydrofluoric acid. The as-prepared nanocomposites were characterised via field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and electrochemical methods. Since the nanocomposite showed a greatly enhanced electrocatalytic activity towards the glucose oxidation in alkaline solution, Ag nanoparticles supported on PSi flour were used as a performance modifier in the construction of a new amperometric glucose screen-printed carbon electrode. The enzymatic free glucose sensor based on AgNPs@PSi exhibited a wide linear dynamic range of 1 × 10−6 –45.7 × 10−3 M, with a detection limit of 6 × 10−7 M at a signal-to-noise ratio of 3, and fast response (<3 s). Also, the response of the proposed sensor was selective towards glucose in the presence of common species such as ascorbic acid, dopamine, uric acid and Cl− ions. Finally, the sensor was successfully applied to determine glucose in human serum samples.

TiO2 nanosheets decorated with B4C nanoparticles as photocatalysts for solar fuel production under visible light irradiation

Boron carbide (B4C) nanoparticles-decorated anatase titanium dioxide (TiO2) nanosheets photocatalysts were synthesized by a hydrothermal method in the presence of hydrofluoric acid and characterized by field emission scanning electron microscope, high-resolution transmission electron microscope, UV–vis diffuse reflectance spectra, photoluminescence spectra, etc. With metallic Pt nanoparticles as a co-catalyst, the as-synthesized B4C/TiO2 composites were evaluated using photocatalytic CO2 or H2O reduction to solar fuels such as methane and hydrogen. Under either simulated sunlight or visible light irradiation, coupling p-type B4C with n-type anatase TiO2 significantly improved the photocatalytic performance. Both photoluminescence and transient photocurrent measurements indicated that the interfacial coupling effect between B4C and anatase TiO2 could significantly promote photo-excited charges separations. On the basis of measurements and literatures, a possible mechanism of excited charges transfer at the B4C-anatase TiO2 heterojunction interface during irradiation was deduced.

Natural and experimental fluorine substitution in biotite: Implications for fluid-rock thermochronometry and application to the Seridó Belt, northeastern Brazil

Abstract We modeled non-steady-state, fluid-assisted diffusion in a sheet plane, infinite cylinder and finite thin cylinder using analytical solutions of the diffusion equation and the experimental diffusivity of F-in-biotite. Diffusion experiments on natural biotite in the presence of hydrofluoric acid at 0.4 GPa and 650, 700, and 750 °C produced diffusive influx perpendicular to the c-axis. EPMA mapping and profiling allow us to define the following Arrhenius expression of F diffusion in biotite: D = 7.04 m 2 s × 10 − 4 × exp − 221 kJ mol RT − 1 The results yield the discrimination of a high-T homogenization domain where cooling paths continuously reequilibrate F-in-biotite, an intermediate-T zonation domain where cooling paths record F-in-biotite diffusion profiles and a low-T closure domain where F-in-biotite remains unchanged. The zonation domain significantly expands with increasing cooling rates and decreasing diffusion time. We systematically analyzed F-in-biotite with electron microprobe in samples collected along representative cross-sections within the Serido Belt, northeastern Brazil. Its metasedimentary units reached upper amphibolite grade metamorphic conditions, with constant F-in-biotite (F ≈ 0.33 wt.%) in grains from mica schist and paragneiss. The Ti-in-biotite geothermometer yielded nearly constant temperatures around 623 °C. The F-in-biotite regional background values remain unchanged at the contact with the major Ediacaran F-rich Acari pluton. It indicates the absence of magmatic fluid influx into the host rocks and is evidence for a fluid-absent nature of melts. By contrast, the F-in-biotite of the metric mica schist enclaves within dykes and sills of Cambrian pegmatitic granites was reequilibrated by interaction with exsolved fluids. The Ti-in-biotite geothermometer indicates temperatures around 642 °C, and our model suggests 100 kyr as a minimal duration for fluid-rock interaction. The preservation of intra-grain F-in-biotite homogeneity requires fluid flux cessation before cooling or fluid-present cooling rates below 100 °C Myr−1. Higher cooling rates would generate F-in-biotite intra-grain zonation. At the contact with the pegmatitic granites, the metasedimentary rocks show meter-scale F-in-biotite gradients due to thermal profiles setting the fluid (fH2O/fHF) gradient. The preservation of such gradients is related to a relatively fast fluid flux episode compared to the overall duration of the elevated thermal profile. The absence of intra-grain zonation indicates that F-in-biotite re-equilibration was fast relative to that of the fluid flux duration. We found intra-grain F-in-biotite zonation within an orthogneiss sample from the Paleoproterozoic Caico complex basement nearby the metasedimentary belt and intruded plutons. The fit of the natural profile by modeled profiles for cooling rates below 10 °C Myr−1, obtained from available Serido Belt U-Pb and 40Ar/39Ar ages, indicates that the orthogneiss cooled from 475 °C. It suggests the existence of a thermal gradient as the inner part of the belt cooled from 623 °C.

Hydrofluoric Acid-Free Electroless Deposition of Metals on Silicon in Ionic Liquids and Its Enhanced Performance in Lithium Storage.

Metal nanoparticles such as Au, Ag, Pt, and so forth have been deposited on silicon by electroless deposition in the presence of hydrofluoric acid (HF) for applications such as oxygen reduction reaction, surface-enhanced Raman spectroscopy, as well as for lithium ion batteries. Here, we show an HF-free process wherein metals such as Sb and Ag could be deposited onto electrodeposited silicon in ionic liquids. We further show that, compared to electrodeposited silicon, Sb-modified Si demonstrates a better performance for lithium storage. The present study opens a new paradigm for the electroless deposition technique in ionic liquids for developing and modifying functional materials.

Amino-Functionalized Layered Crystalline Zirconium Phosphonates: Synthesis, Crystal Structure, and Spectroscopic Characterization.

Two new layered zirconium phosphonates functionalized with amino groups were synthesized starting from aminomethylphosphonic acid in the presence of different mineralizers, and their structures were solved from powder X-ray diffraction data. Their topologies are unprecedented in zirconium phosphonate chemistry: the first, of formula ZrH[F3(O3PCH2NH2)], prepared in the presence of hydrofluoric acid, features uncommon ZrO2F4 units and a remarkable thermal stability; the second, of formula Zr2H2[(C2O4)3(O3PCH2NH2)2]·2H2O, prepared in the presence of oxalic acid, is based on ZrO7 units with oxalate anions coordinated to the metal atom, which were never observed before in any zirconium phosphonate. In addition, the structure of another compound based on (2-aminoethyl)phosphonic acid is reported, which was the object of a previously published study. This compound has layered α-type structure with -NH3(+) groups located in the interlayer space. All of the reported compounds were further characterized by means of vibrational spectroscopy, which provided important information on fine structural details that cannot be deduced from the powder X-ray diffraction data.

Synthesis of highly-ordered TiO2 nanotube arrays with tunable sizes

Vertically-oriented one-dimensional TiO2 nanotube (TNT) arrays have been fabricated by anodic oxidation using different electrolyte solvents, including ethylene glycol (EG), diethylene glycol (DEG), and dimethyl sulfoxide (DMSO), in the presence of hydrofluoric acid (HF) or ammonium fluoride (NH4F). The influence of synthetic conditions, including the nature of the electrolyte and anodization voltage, on nanotube microstructure has been systematically investigated. Highly-ordered TNTs with tube length of ∼0.5–26.7 μm, inner diameter of ∼13–201 nm, and outer diameter of ∼28–250 nm have been obtained. The conversion of as-prepared TNT arrays from amorphous phase to crystalline structure has been achieved by a post-synthetic annealing at 500 °C for 3 h in oxygen ambient. The TNT arrays with tunable sizes and structures are attractive for use as electrode materials in fabrication of thin film solar cells and highly active photocatalysts.

Template-assisted synthesis of biodegradable and pH-responsive polymer capsules via RAFT polymerization for controlled drug release

The preparation of pH responsive, biodegradable, biocompatible and cross-linked polymer capsules for controlled drug release is presented. These capsules were prepared using silica particles as templates for surface grafting of poly (acrylic acid) (PAA) and PAA-co-poly(polyethylene glycol) acrylate) (PAA-PPEGA) block copolymer via reversible addition fragmentation chain transfer (RAFT) polymerization directly from silica particles, followed by cross-linking with cystamine dihydrochloride and removal of the silica template in the presence of hydrofluoric acid, respectively. The resultant polymer capsules were water soluble, biocompatible with a mean diameter of approximately 260 ± 10 nm, and non-toxic to human cells at low concentration, which are favorable to be utilized as drug carriers for pH responsive and biodegradation controlled drug release. Doxorubicin hydrochloride (DOX) was chosen as a model drug to test the drug loading and releasing properties of the polymer capsules. It was found that the DOX could be effectively loaded into the PAA and PAA-PPEGA capsules with a loading capacity up to 52.24% and 36.74%, respectively. The pH and biodegradation controlled release behaviors of DOX loaded PAA-PPEGA capsules were also explored. The results imply that both PAA and PAA-PPEGA capsules are promising platforms for pH and biodegradation controlled drug delivery systems, while the PAA-PPEGA capsules exhibit less cytotoxicity.

Cr-MIL-101 encapsulated Keggin phosphotungstic acid as active nanomaterial for catalysing the alcoholysis of styrene oxide

Mesoporous chromium-based terephthalate metal–organic framework (MIL-101) encapsulated Keggin phosphotungstic acid (HPW) [MIL-101(HPW)] was demonstrated to be an active heterogeneous catalyst for selective catalysis of the ring opening reaction of styrene oxide with methanol, achieving 99% yield of 2-methoxy-2-phenylethanol in 20 minutes at 40 °C. Similar MIL-101 samples prepared using one-pot microwave synthesis in the absence of HPW or in the presence of hydrofluoric acid (HF) were less active. The impact of fluoride and HPW polyanion incorporation on the acidity of MIL-101 was investigated by the in situ infrared spectroscopy technique using CO as a probe molecule. Additional hydroxyl groups and Lewis acid sites are present in MIL-101(HPW) explaining the observed superior catalytic performance in styrene oxide methanolysis.

The Photocatalysis Properties of Heterostructured WO&lt;sub&gt;3&lt;/sub&gt;-TiO&lt;sub&gt;2&lt;/sub&gt; Composite Prepared by Waste WC-TiC Hardmetal

We reported a facile hydrothermal route for the preparation of WO3TiO2 composite nanoparticles (TWCNs) using waste WC-TiC hardmetal in the presence of hydrofluoric acid (HF). Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and nitrogen adsorption/desorption analysis were employed for structural and composition analyses of the TWCNs. Our results suggested that HF was not only strongly involved in the growth of WO3, but also played a critical role in the etching effect for TWCN product. The photocatalytic activity of TWCNs was investigated by UV-vis spectroscopy. Dye molecules could be rapidly decomposed with TWCNs photocatalyst under visible light illumination. The enhanced photocatalytic activity is attributed to well matched band edge positions of WO3 and TiO2, and the large specific surface area of TWCNs in view of the incorporation of mesopores. The results presented here are expected to make a contribution toward the development of recycling waste resource delicately for photocatalytic water purification.

Comparative study of initial stages of copper immersion deposition on bulk and porous silicon

Initial stages of Cu immersion deposition in the presence of hydrofluoric acid on bulk and porous silicon were studied. Cu was found to deposit both on bulk and porous silicon as a layer of nanoparticles which grew according to the Volmer-Weber mechanism. It was revealed that at the initial stages of immersion deposition, Cu nanoparticles consisted of crystals with a maximum size of 10 nm and inherited the orientation of the original silicon substrate. Deposited Cu nanoparticles were found to be partially oxidized to Cu2O while CuO was not detected for all samples. In contrast to porous silicon, the crystal orientation of the original silicon substrate significantly affected the sizes, density, and oxidation level of Cu nanoparticles deposited on bulk silicon.

Thermal treatment and environment effect on transient photoconductivity behavior of anatase TiO2 with dominant {0 0 1} facets

Nanosized anatase TiO2 powders with dominant {001} facets were prepared by solvothermal reaction of titanium isopropoxide in the presence of hydrofluoric acid as a capping agent. Two kinds of samples, as prepared and calcinated at 600°C were fabricated and their UV–Visible and transient photoconductivity were investigated in vacuum and in air. The photoconductivity reaches high values and is sensitive on the environment. Thermal treatment improves the crystalline quality and enhances the amount of created excess charge carriers.

Metal-Controlled Assembly of Uranyl Diphosphonates toward the Design of Functional Uranyl Nanotubules

Two uranyl nanotubules with elliptical cross sections were synthesized in high yield from complex and large oxoanions using hydrothermal reactions of uranyl salts with 1,4-benzenebisphosphonic acid or 4,4'-biphenylenbisphosphonic acid and Cs(+) or Rb(+) cations in the presence of hydrofluoric acid. Disordered Cs(+)/Rb(+) cations and solvent molecules are present within and/or between the nanotubules. Ion-exchange experiments with A(2){(UO(2))(2)F(PO(3)HC(6)H(4)C(6)H(4)PO(3)H)(PO(3)HC(6)H(4)C(6)H(4)PO(3))}·2H(2)O (A = Cs(+), Rb(+)), revealed that A(+) cations can be exchanged for Ag(+) ions. The uranyl phenyldiphosphonate nanotubules, Cs(3.62)H(0.38)[(UO(2))(4){C(6)H(4)(PO(2)OH)(2)}(3){C(6)H(4)(PO(3))(2)}F(2)]·nH(2)O, show high stability and exceptional ion-exchange properties toward monovalent cations, as demonstrated by ion-exchange studies with selected cations, Na(+), K(+), Tl(+), and Ag(+). Studies on ion-exchanged single crystal using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS) provide evidence for chemical zonation in Cs(3.62)H(0.38)[(UO(2))(4){C(6)H(4)(PO(2)OH)(2)}(3){C(6)H(4)(PO(3))(2)}F(2)]·nH(2)O, as might be expected for exchange through a diffusion mechanism.

Ionothermal synthesis and crystal structures of metal phosphate chains

We have prepared isostructural aluminium and gallium phosphate chains by ionothermal reactions in 1-ethyl-3-methylimidazolium bromide and 1-ethylpyridinium bromide under a variety of conditions. The chains can be prepared as pure phases or along with three dimensional framework phases. The chains are favoured at shorter heating times and the crystallinity can be improved by addition of transition metal acetates and amines which are not included in the final structure. The chain can be prepared with or without the presence of hydrofluoric acid.

SELF-ASSEMBLED POLYANILINE MICRO/NANOTUBES DOPED WITH HYDROFLUORIC ACID

Self-assembled micro/nanotubes of polyaniline(PANI) with a high conductivity(10~(-2)～10~(-1)S/cm) were synthesized by a template-free method in the presence of hydrofluoric acid(HF) as the dopant.The formation probability of PANI-HF micro/nanotubes was nearly 100% when the molar ratio of / was equal to 0.5.The SEM and TEM images revealed that the average diameter of the micro/nanotubes was about 85～420 nm.Besides,it was found that the diameter and conductivity of micro/nanotubes at room-temperature increase with the increase of / ratios.The micro/nanotubes characterized by FTIR and UV-Visible absorption spectrums are identical to the emeraldine salt state of PANI.