Neutron activation determination of gold in technogenic raw materials with different mineral composition

The methods used to determine the gold content in the technogenic objects of gold mining were analyzed regarding their non-homogeneity and complexity of chemical and mineral compositions. A possible application of the neutron activation analysis with the use of the californium source of neutrons for determining the content of fine-grained and extra-fine-grained gold in the technogenic objects, including the bottom-ash waste of energy providers, is considered. It was demonstrated that the chemical composition of the sample affects the neuron flux distribution in the sample, which can essentially distort the results of the neutron activation analysis. In order to eliminate possible systematic errors investigations of the effect of the sample mineral composition on the results of the gold determination using the neutron activation analysis were carried out. Namely, a large mass of rock (3-5 kg) was loaded into an activation zone using four matrix types such as silicate, carbon-containing, iron-containing, and titanium magnetite. It was shown that there wereno significant difference between the dispersal of the fluxes of thermal and resonance neutrons emitted from 252Cf during activation of the gold-containing technogenic samples with different mineral compositions

Zr4+/F– co-doped TiO2(anatase) as high performance anode material for lithium-ion battery

Zr4+ and F– co-doped TiO2 with the formula of Ti0.97Zr0.03O1.98F0.02 was facilely synthesized by a sol-gel template route. The crystal structure, morphology, composition, surface area, and conductivity were characterized by Raman spectroscopy, energy-dispersive X-ray analysis, scanning electron microscopy, Brunauer−Emmett−Teller measurements, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. The results demonstrate that Zr4+ and F– homogeneously incorporated into TiO2, forming solid solution with an anatase structure. Ti0.97Zr0.03O1.98F0.02 shows outstanding electrochemical properties as Li-ion battery anode in comparison with Ti0.97Zr0.03O2. In particular, upon 35-fold cycling at 1C-rate Zr4+/F– co-doped TiO2 delivers a reversible capacity of 163 mAh g–1, whereas Zr4+-doped TiO2 gives only 34 mA h g–1. Additionally, Zr4+/F– co-doped TiO2 retains a capacity of 138 mA h g–1 during cycling even at 10 C. The enhance performance originates from improved conductivity of Zr4+/F– co-doped TiO2 material through generation of Ti3+ (serving as electron donors) into the crystal lattice and, possibly, due to F-doping blocked the anode surface from attack of HF formed as electrolyte decomposition product. Keywords: Li-ion batteries, TiO2(anatase), Anode, Co-doping, Sol-gel template, Process, Electrochemical performanc

Cesium uptake by pentacyanoferrate(II) complexes with O-containing derivatives of chitosan

<p>Here we report on synthesis of new organic-inorganic materials based on products of interaction between sodium aminoprusside and polymer ligands. Fourier transform infrared (FT-IR) and UV-visible spectroscopy and thermogravimetry were used to investigate the structure and stability of the complexes. It was found that ion and ligand exchange were the main reactions of the interaction of sodium aminoprusside with water-soluble polymer salts. All other composites in the Co(II) form were characterized in terms of sorption capacities and distribution coefficients (K_d) for cesium ions. The highest values of distribution coefficients were obtained for polyampholyte chitosan derivatives.</p

Polymer-Inorganic Coatings Containing Nanosized Sorbents Selective to Radionuclides. 1. Latex/Cobalt Hexacyanoferrate(II) Composites for Cesium Fixation

Here we present a new approach to improve fixation of radionuclides on contaminated surfaces and eliminate their migration after nuclear accidents. The approach consists in fabrication of latex composite coatings, which combine properties of polymeric dust-suppressors preventing radionuclides migration with aerosols and selective inorganic sorbents blocking radionuclides leaching under contact with ground waters and atmospheric precipitates. Latex/cobalt hexacyanoferrate­(II) (CoHCF) composites selective to cesium radionuclides were synthesized via “in situ” growth of CoHCF crystal on the surface of carboxylic or amino latexes using surface functional groups as ion-exchange centers for binding precursor ions Co²⁺ and [Fe­(CN)₆]^4–. Casting such composite dispersions with variable content of CoHCF on ¹³⁷Cs-contaminated sand has yielded protective coatings, which reduced cesium leaching to 0.4% compared to 70% leaching through original latex coatings. ¹³⁷Cs migration from the sand surface was efficiently minimized when the volume fraction of CoHCF in the composite film was as low as 0.46–1.7%

Data

The Data.zip consists of the data of Figures (from Figure 1 to Figure 9). The files can be opened by specific software such as Diffrac Plus 1.01 for XRD, SpecsLab 2.23 for XPS, SigmaPlot Workbook 12.0 for Raman, TA60 2.01 for TGA, ZView 3.4c and Origin 8.0 for electrochemical data

Data from: Effect of Hf-doping on electrochemical performance of anatase TiO2 as an anode material for lithium storage

Hafnium-doped titania (Hf/Ti = 0.01; 0.03; 0.05) had been facilely synthesized via a template sol-gel method on carbon fiber. Physicochemical properties of the as-synthesized materials were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, scanning transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetry analysis, and Brunauer−Emmett−Teller measurements. It was confirmed that Hf4+ substitute in the Ti4+ sites, forming Ti1–xHfxO2 (x = 0.01; 0.03; 0.05) solid solutions with an anatase crystal structure. The Ti1–xHfxO2 materials are hollow microtubes (length of 10–100 μm, outer diameter of 1–5 μm) composed of nanoparticles (average size of 15–20 nm) with surface area of 80–90 m2 g–1 and pore volume of 0.294–0.372 cm3 g–1. The effect of hafnium ions incorporation on electrochemical behavior of anatase TiO2 as Li-ion battery anode was investigated by galvanostatic charge/discharge and electrochemical impedance spectroscopy. It was established that Ti0.95Hf0.05O2 shows significantly higher reversibility (154.2 mAh g–1) after 35-fold cycling at C/10 rate in comparison with undoped titania (55.9 mAh g–1). The better performance offered by Hf4+ substitution of the Ti4+ into anatase TiO2 mainly results from more open crystal structure, which has been achieved via the difference in ionic radius values of Ti4+ (0.604 Å) and Hf4+ (0.71 Å). The obtained results are in a strong accordance with ones for anatase TiO2 doped via Zr4+ (0.72 Å) published earlier. Furthermore, improved electrical conductivity of Hf-doped anatase TiO2 materials due to charge redistribution in the lattice and enhanced interfacial lithium storage due to increased surface area directly depending on Hf/Ti atomic ratio have beneficial effect on electrochemical properties

Supplementary Figures and Tables from Effect of Hf-doping on electrochemical performance of anatase TiO₂ as an anode material for lithium storage

Figure S1: SEM image and elemental mapping of Ti, O, and Hf for Ti_0.95Hf_0.05O₂; Figure S2: XPS high-resolution spectra of (a) Ti 2p, (b) O 1s, (c) Hf 4f, and (d) C 1s regions for Ti_0.95Hf_0.05O₂ sample; Figure S3: Dependence of Z^' on ω^–1/2 at low frequencies; Table S1: Binding energy and atomic concentration of elements in Ti_0.95Hf_0.05O₂ sample; Table S2: Dependence of <i>E</i>_g(1), <i>B</i>_1<i>g</i>(1), and <i>E</i>_<i>g</i>(3) peaks positions on Hf/Ti atomic rati