Preparation of some transition metal sulphides

Ternary sulphides, LnMS₃ (Ln=rare earth metal; M=first row transition metal) and MV₂S₄ (M=Mg, Fe, Co, Ni and Zn) have been prepared by the reaction of appropriate ternary metal oxides with H₂S or CS₂/N₂ vapours at elevated temperatures. Chemical analysis and x-ray powder diffraction of the products indicate formation of single-phases with unique crystal structures in many cases. Communication No. 117 from the Solid State and Structural Chemistry Unit.     

ISO发布化妆品防晒性能测试方法评估新规范

国际标准化组织（ISO）近期发布了一份有关化妆品防晒性能测试方法的技术报告（TR）．以期对市场上大量存在的各种防晒性能测试方法进行有效的评估。     

Chemical diffusion in non-stoichiometric metal sulphides

Transport properties of transition metal sulphides have been discussed in terms of chemical and self-diffusion coefficients. It has been shown that in the case of highly non-stoichiometric sulphides (Co_1?yS) the chemical diffusion coefficient may easily be obtained from thermogravimetric measurements of re-equilibration kinetics. If the non-stoichiometry and thereby defect concentration is low (Mn_1?yS), the re-equilibration kinetics is difficult or impossible to follow thermogravimetrically, and the electrical conductivity method can be applied. If the non-stoichiometry of a given metal sulphide is known as a function of temperature and sulphur activity, chemical diffusion data may successfully be utilized for calculation of parabolic rate constants of metal sulphidation and to obtain better insight into the growth mechanism of the sulphide scale. Using this procedure it has been shown that the sulphide scales on cobalt and manganese grow by the outward volume diffusion of cations. The chemical diffusion coefficient may also be used in the calculation of the self-diffusion coefficient of cations (or anions) if the non-stoichiometry data of a given sulphide are available. It has been shown that the self-diffusion coefficients of manganese in Mn_1?yS obtained in such a way are in full agreement with those determined experimentally.     

Electrodeposition of ZnO nanorods in the presence of metal ions

We report on structural and optical changes induced by impurity incorporation in ZnO nanorods grown via electrodeposition. We find the lattice parameters of the hexagonal ZnO rods to be larger than in defect-free single-crystalline ZnO. SIMS measurements indicate impurity incorporation and doping in the bulk of the nanorods. The impurity content correlates with changes in the electroluminescence spectra. The maximum of the defect luminescence band around 600 nm shifts towards longer wavelengths with metal incorporation. Aluminum incorporation leads to a narrow luminescence band close by the bandgap of ZnO around 390 nm.     

Isotopic fractionation during diffusion of transition metal ions in solution

Isotope ratios and elemental concentrations were measured in aqueous solutions sampled at varying distances from sources of Fe or Zn ions. The measurements reveal fractionation of isotopes resulting from pure diffusion in solution. Our data demonstrate that diffusion alone can cause changes in (56)Fe/(54)Fe and (66)Zn/(64)Zn isotope ratios in excess of -0.3 per thousand. These findings thus confirm previous suspicions that transport processes contribute to observed variations in isotopic compositions. Diffusion must therefore be considered when attempting to make inferences from isotope measurements on samples originating from aqueous systems where concentration gradients may develop.     

The influence of transition metal ions on collagen mineralization

The ions in body fluid play an important role in bone formation besides being a synthesizing material. Transition metal ions Co^2 +, Ni^2 +, Zn^2 +, Fe^3 +, Mn^2 +, Cu^2 +, Cd^2 + and Hg^2 + doped hydroxyapatite (HAP)/collagen composites were synthesized successfully in the presence of collagen traces at mild acidic pH for the first time. However, the amount of doped Hg^2 + and Cd^2 + was relatively low. Meanwhile, through soaking the collagen sponge as a template in simulated body fluid (SBF) which contains different transition metal ions (Mn^2 +, Cu^2 +, Ni^2 +, Co^2 +, Cd^2 +, Hg^2 +), bone-like HAP/collagen composites were synthesized. Hg^2 + had a certain inhibitory effect on the formation of HAP crystals on the surface of the collagen sponge while Co^2 + can promote the formation of HAP on the collagen sponge. For both HAP/collagen composites and HAP/collagen sponge, it was found that transition metal ions Mn^2 + had a significant effect on the morphology of HAP particles and could induce to form floc-like HAP particle aggregates.     

Dissolution of calcite crystals in the presence of some metal ions

A constant composition method has been used for the study of the kinetics of calcium carbonate (calcite) dissolution in which the activities of ionic species in relatively undersaturated solutions are maintained constant. Over a range of relative undersaturation (0.032–0.158) the dissolution reaction appears to be controlled by a bulk diffusion process. The suggestion of a predominantly diffusion-controlled process was supported by the observed low activation energy (2.09 kcal mol^–1). The influence of a number of metal ions on the reaction rate has been investigated. The retardation effect of these additives has been attributed to the blocking of active sites by adsorption of metal ions at the crystal surfaces. Inhibition of dissolution by metal ions can be interpreted in terms of a Langmuir isotherm.     

Coordination and valence state of transition metal ions in alkali-borate glasses

Borate glasses of the 20R₂O·80B₂O₃ type, where R = Li, Na and K, were colored by doping with transition metal ions (Co, Ni, Cr and Mn). The glasses were obtained by melting at the temperature of 1150 °C. For these glasses optical absorption in UV–VIS–NIR range were recorded. Analysis of the spectra allows to be determined the coordination and oxidation states of the doping transition metal ions. Changes of their coordination or oxidation are presented as a function of the optical basicity Λ after Duffy. Cobalt and nickel are present in examined borate glasses as divalent ions (Co²⁺, Ni²⁺) in octahedral coordination mainly, but the tetrahedral coordination state of cobalt is also possible. Chromium and manganese are present in the borate glasses in various oxidation state, though Cr³⁺ and Mn³⁺ ions in the octahedral coordination are probably dominant. A decrease of the electronegativity of the modifiers (Li → Na → K) and an increase of the glass matrix basicity cause a shift of the oxidation/reduction equilibrium towards higher valences of the transition metals (Cr⁶⁺, Mn³⁺).     

Magnetic properties of sulfate glasses doped with transition metal ions

Magnetic susceptibility measurements on ZnSO₄K₂SO₄ glasses containing high concentrations of Mn²⁺, Co²⁺ or Ni²⁺ ions suggest the presence of weak ferromagnetic interaction.     

Electron spin resonance in phosphate glasses containing mixed transition metal ions

Phosphate glasses containing mixed Cu²⁺/Ni²⁺ and Cu²⁺/Co²⁺ oxides have been examined. A pronounced decrease in the optical absorption at 830 nm due to the Cu²⁺ ions is observed as the CuO in the glasses is gradually replaced by NiO or CoO and the decrease is accompanied by a pronounced decrease in the strength of the electron spin resonance (ESR) signal at 9.52 GHz. By combining the ESR and optical absorption data it is concluded that the decrease in concentration of Cu²⁺ ions in phosphate glasses may be due to an oxidation-reduction mechanism between two valency states of the two different transition metals, of the form Cu²⁺+Ni⁺Cu⁺+Ni²⁺ and Cu²⁺+Co⁺Cu⁺+Co²⁺.     

Crystal growth and characterization of beryl doped with transition metal ions

Beryl crystals containing transition metal ions (Cr³⁺, Fe³⁺, Fe²⁺ and Mn²⁺) have been grown from Li₂Mo₂O₇ mineralizing flux.The crystal growth procedure, X-ray examination and optical characterization of the crystals are described.     

一种喹啉苯腙的合成及其对金属离子的识别

以4-硝基苯肼、8-羟基喹哪啶等为原料设计合成了8-羟基-2-喹啉甲醛-4-硝基苯腙(1),经元素分析、1H NMR对其结构进行了表征。在V(二甲亚砜)/V(甲醇)=1∶9混合溶剂中采用UV-Vis光谱法研究了苯腙(1)对Li+、K+、Mg2+、Ca2+、Mn2+、Co2+、Ni2+、Zn2+、Cd2+、Hg2+、Fe2+、Fe3+及Cu2+离子的识别性能。结果表明,苯腙1仅对Cu2+和Zn2+有特殊的识别能力,加入Cu2+或Zn2+的苯腙1溶液由黄色分别变为橙色和红色,其光谱在413 nm处的吸收峰强度减小,且分别在485和508 nm附近产生新的吸收峰。竞争实验表明,苯腙1对Zn2+的检测不受除Cu2+以外上述其它阳离子影响,而对Cu2+的检测不受上述任何其它阳离子的影响。线性拟合结果显示,苯腙1与Cu2+和Zn2+分别形成了1∶1和1∶2的配合物。     

Synthesis and characterisation of polyol-capped transition metal oxide nanoparticles

In-situ capped nanocrystalline gamma-Fe2O3, Co3O4, and Cu2O were prepared in 1,4-butanediol in aerobic conditions. X-ray diffraction (XRD) patterns show that the synthesised samples are nanocrystalline cubic oxides with crystallite sizes 9.5 nm, 13.4 nm, and 11 nm, respectively. Raman spectroscopy shows peaks at 350 cm(-1), 500 cm(-1), and 700 cm(-1), indicating that the iron oxide is gamma-Fe2O3; M?ssbauer spectroscopy shows the presence of two Fe3(3+) sites. Transmission electron microscopy images show that the particle sizes of gamma-Fe2O3 and Co3O4 samples are 8.9 nm and 7 nm, respectively. The absence of agglomeration indicates that the synthesised nanoparticles are capped. FT-IR spectra show the presence of an organic moiety in the sample which acts as a capping agent. Thermogravimetry shows that the capping is stable up to 873 K in gamma-Fe2O3, and up to 400 K in Co3O4. The samples are soluble in water to form stable hydrosols. During synthesis of gamma-Fe2O3 a 6-line ferrihydrite is formed as an intermediate, which is stable in solution up to 473 K, and transforms to gamma-Fe2O3 at 483 K, by rapid dissolution-reprecipitation. In the syntheses of Co3O4 and Cu2O, no intermediates are formed.     

Gamma rays interaction with bismuth borate glasses doped by transition metal ions

Ultraviolet, visible, and infrared spectroscopic measurements have been employed to investigate undoped binary bismuth borate glass (60 mol% Bi₂O₃, 40 mol% B₂O₃) and doped samples with 0.2% 3d transition metal oxides in order to obtain information about the role of all the constituents oxides including the dopants on the measured properties. The undoped sample shows strong extended UV-near visible absorption bands which are attributed to both trace iron impurities from raw materials used for glass preparation and Bi³⁺ ions. The TM-samples show the same strong UV-near visible absorption as the undoped sample beside characteristic visible bands because of TM ions. The prepared samples show obvious shielding behavior toward the effect of successive gamma irradiation especially in the visible region. The infrared absorption spectra of the prepared samples show characteristic bands related to the sharing of triangular and tetrahedral borate groups together with Bi–O groups. The IR spectra are slightly affected by gamma irradiation indicating the stability of network forming units while the modifier, OH and water bands show obvious changes in their intensities.     

Production new chelating fibers of polyacrilonitrile for removing metal ions

In this work, raw acrylic fibers (RAF) have been modified with ethanolamine to provide new chelating fibers and prepared polyacrylonitrile‐monoethanolamine (PAN‐MEA). PAN‐MEA fiber was prepared by conversion nitrile groups into hydroxyle groups using ethanolamine solution with different concentration under refluxing at different temperatures and different times. The fiber structure has been investigated by different experimental techniques of characterization such as Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and the physical and mechanical properties has also been investigated in this study. The PAN‐MEA was examined as chelating material in a series of batch adsorption experiments for removal Cu (II), Pb (II) and Ni (II) ions. The ion adsorption of PAN‐MEA was determined with the atomic adsorption method. PAN‐MEA show adsorption metal ions more than usual fiber because of the modification.     

新型螯合纤维在金属离子富集分离中的应用

近年来,螯合纤维在金属离子的提取、分离、分析等方面的研究成为分离科学领域的研究热点。螯合纤维对金属离子具有很强的吸附性和高的选择性,可以用于放射性金属、贵金属、过渡金属和稀土金属离子的回收、富集和分离等方面。为了进一步提高螯合纤维的吸附性和选择性,众多学者对如何制备出性能优良的螯合纤维进行了大量的研究工作。综述了近年来新型螯合纤维的制备和吸附性能。     

Effect of thermal stabilization on the optical absorption of some transition metal ions in glass

The optical absorption of a 30Na₂O, 70SiO₂ glass containing iron, chromium or cerium has been studied after thermal stabilization at various temperatures around the transformation range of the glass. The optical absorptions due to iron(II), iron(III), cerium(III) and cerium(IV) have been found to increase with increasing stabilization temperature; the optical absorptions due to chromium(III) and chromium(VI) do not change significantly with stabilization temperature. The changes in optical absorption due to stabilization at different temperatures have been found to be reversible and reproducible. It has been argued that as the equilibrium volume of a given mass of glass increases with increasing stabilization temperature, and as the ligand field strength surrounding the transition metal ion does not increase due to this enlargement of volume while the optical absorption increases, the high temperature stabilization of a glass probably increases some local randomness of structure (creating extra distortion of the transition metal complex) and does not cause an uniform volume expansion of the glass.     

Colorimetric and fluorescent sensing of transition metal ions in aqueous medium by salicylaldimine based chemosensor

The cation sensing property of highly sensitive chromogenic receptor N, N′-bis (salicylidine)-o-phenylene diamine (receptor 1) was studied by visual observation, UV–vis spectroscopy and fluorescence spectroscopy. The proposed study has been targeted to sense the first transition series metal cations like Fe³⁺, Co²⁺, Ni²⁺ and Cu²⁺. Binding affinity toward Cu²⁺ is found to be of higher magnitude compared to the other three cations mentioned. Receptor 1 on binding with Fe³⁺, Co²⁺ Ni²⁺ and Cu²⁺ ions shows fluorescence enhancement which is due to the inhibition of PET mechanism.