Ion-selective chalcogenide electrodes for a number of cations

Ion-selective chalcogenide disc electrodes have been developed which are responsive to cations such as silver, lead, chromium(III), nickel, cobalt(II), cadmium, zinc, copper(II) and manganese(II) ions. Each was prepared by using the corresponding metal chalcogenide with silver sulphide. An electrode was assembled with both a compacted and a sintered disc. The sintered electrodes were more sensitive and stable than the compacted ones. Response to silver ion was 59.5 mV pAg , to lead, nickel, cadmium, zinc and copper(II) 29.5 mV pM and to chromium(III) 20 mV pM . Cobalt(II) and manganese(II) electrodes had a non-Nernstian response of 25 mV pM . Both selenides and tellurides can be used for potentiometric determination, but the manganese(II) electrode serves as an analytical tool only when the disc consists of manganese(II) telluride and silver sulphide.     

Extraction of contaminant metals from dumped metacolloid ores in order to reduce their hazardousness

Problems of human and environmental protection from discharges formed in out-of-balance ores dumped from nonferrous metallurgy were considered. To the most hazardous dumps belong those of metacolloid ores, discharges from which are contaminated with copper, zinc, iron, and also indium and cadmium. It was found that the most effective way to preclude the contamination is by using heap leaching of contaminant metals from ores in the chemical reclamation of the dumps. Mathematical dependences of the leaching rate of easily soluble compounds of metals (copper, zinc, indium, and cadmium) from metacolloid ores on the main technological factors of the process: sulfuric acid concentration, ore spraying density, and oxidation interval between sprayings were determined, the optimal process modes were found, and the cost-efficient production of metals in reclamation of dumps of this kind to a state in which they hardly contaminate the environment was calculated.     

Spectrophotometric and spectrofluorometric determination of zinc and cadmium with 2,2'-pyridil bis(2-quinolylhydrazone)

The chelating ligand, 2,2'-pyridil bis(2-quinolylhydrazone), has been used for the spectrophotometric determination of zinc and cadmium in synthetic samples. The molar absorptivities of these metal complexes in 80% ethanol-water solution at pH 8 were found to be 4.60 x 10(4) and 5.10 x 10(4) 1.mole(-1).cm(-1) for zinc and cadmium respectively. Beer's law was obeyed for metal-ion concentrations between 1.0 x 10(-6) and 2.5 x 10(-5)M. The limits of detection were found to be 52 and 79 ng ml for zinc and cadmium respectively. The complexes fluoresced in 80% ethanol-water at pH 8 for zinc and at pH 10 for cadmium. The linear range for fluorescence as a function of metal-ion concentration was found to be 5 x 10(-7)-5 x 10(-6)M for both zinc and cadmium. Transition-metal ions interfere severely with both the spectrophotometric and fluorimetric determinations, and must be removed beforehand. An ion-exchange procedure is suitable for this.     

Fractionation of cadmium in tobacco and cigarette smoke condensate using XANES and sequential leaching with ICP-MS/MS

Analytical and Bioanalytical Chemistry - Fractionation data for cadmium in tobacco products, as obtained by sequential leaching of cadmium species with ICP-MS/MS analysis, and separately by X-ray...     

Kinetically controlled separation of cadmium(II) from zinc(II) with dithizone in the presence of nitrilotriacetic acid.

The extraction rates of cadmium(II) and zinc(II) with dithizone (H2dz) in the presence of nitrilotriacetic acid (NTA) were measured, and the possible kinetic separation of cadmium(II) from zinc(II) was investigated. Upon the addition of NTA, the difference in the extraction rate between cadmium(II) and zinc(II) became large. Based on the observed rate constant under the condition [NTA] = 1 x 10(-2) mol dm-3, [H2dz]org = 1 x 10(-3) mol dm-3, and pH = 7.0, the shaking time required for the quantitative separation of cadmium(II) from zinc(II) was calculated to be between 326 and 995 s. The experimental results agreed with the prediction, and the quantitative separation of cadmium(II) from zinc(II) was performed within the above-mentioned range of shaking times.     

Kinetic effect of zinc(II) and cadmium(II) ions on configurational inversion of deltaLLL-fac(S)-tris(L-cysteinato-N,S)cobalt(III) complex.

It has been confirmed from circular dichroism (CD) spectral changes of aqueous solutions of deltaLLL-fac(S)-[Co(L-cys-N,S)3]3- that the absolute configurational inversion to the ALLL isomer is remarkably accelerated by zinc(II), while it is retarded by cadmium(II). In the diluted solutions of these metal ions containing excess deltaLLL-fac(S)-[Co(L-cys-N,S)3]3-, the observed inversion rate constant linearly depends on the zinc(II) concentration with an intercept, while it is not affected by the cadmium(II) concentration. The kinetic behavior has been explained by difference between zinc(II)- and cadmium(II)-interactions with lone pairs on sulfur donor atoms of fac(S)-[Co(L-cys-N,S)3]3-. It has also been proposed that concentrations of zinc(II) and cadmium(II) can be simultaneously determined by the kinetic measurements.     

软配位原子效应在锌和镉分离中的应用

研究了锌和镉在二（１,１,３,３－四甲基丁基）膦酸（ＨＭＢＰ）及二（１,１,３,３－四甲基丁基）巯基膦酸（ＨＭＴＰ）／环己烷－硝酸体系中的萃取行为。以软配位原子－硫取代ＨＭＢＰ分子中的羟基氧原子而得到的ＨＭＴＰ对镉具有良好的选择性,以ＨＭＴＰ为萃取剂,仅一次萃取可以实现锌和镉的定量分离。     

Spectrophotometric determination of micro amounts of mercury,cadmium, and zinc by stepwise extraction with tribenzylamine

A rapid spectrophotometric method has been developed for the stepwise determination for mercury, cadmium, and zinc in mixtures. Optimal conditions have been established for the extraction efficiency of cadmium and mercury with a chloroform solution of tribenzylamine pre-equilibrated with hydrobromic acid. After addition of dithizone solution to the organic layers the absorbance at 490 nm or 510 nm is measured for mercury or cadmium, respectively. Even when the ratio of mercury, cadmium, and zinc is 10^-1 : 1 : 10^-5 , the metals can be determined successively.     

Reactions of laser-ablated zinc and cadmium atoms with CO: infrared spectra of the Zn(CO)x (x = 1-3), CdCO-, and Cd(CO)2 molecules in solid neon

Reactions of laser-ablated zinc and cadmium atoms with carbon monoxide molecules in solid neon have been investigated using matrix-isolation infrared spectroscopy. Based on the isotopic substitution, absorptions at 1852.2, 1901.9, 1945.9, and 1995.2 cm(-1) are assigned to the C-O stretching vibrations of the ZnCO, Zn(CO)(2), and Zn(CO)(3) molecules. Absorptions at 1735.8, 1961.3, and 2035.7 cm(-1) are assigned to the C-O stretching vibrations of the CdCO(-) and Cd(CO)(2) molecules. In contrast with the previous argon experiments, more species and more valuable information about the reaction of zinc and cadmium atoms with CO have been obtained in solid neon. Density functional theory calculations have been performed on these zinc and cadmium carbonyls. The agreement between the experimental and calculated vibrational frequencies, relative absorption intensities, and isotopic shifts substantiates the identification of these carbonyls from the matrix infrared spectrum. The present experiments also reveal that zinc is more reactive with CO than cadmium.     

Determination of cadmium, copper, lead and zinc in water samples by flame atomic absorption spectrometry after cloud point extraction

Cloud point extraction (CPE) has been used for the simultaneous pre-concentration of cadmium, copper, lead and zinc after the formation of a complex with 1-(2-thiazolylazo)-2-naphthol (TAN), and later analysis by flame atomic absorption spectrometry (FAAS) using octylphenoxypolyethoxyethanol (Triton X-114) as surfactant. The chemical variables affecting the separation phase and the viscosity affecting the detection process were optimized. At pH 8.6, pre-concentration of only 50 ml of sample in the presence of 0.05% Triton X-114 and 2×10⁻⁵ mol l⁻¹ TAN permitted the detection of 0.099, 0.27, 1.1 and 0.095 ng ml⁻¹ cadmium, copper, lead and zinc, respectively. The enhancement factors were 57.7, 64.3, 55.6 and 63.7 for cadmium, copper, lead and zinc, respectively. The proposed method has been applied to the determination of cadmium, copper, lead and zinc in water samples and a standard reference material (SRM).     

Determination of cadmium and zinc in waters by flame atomic absorption spectrometry after cloud-point extraction

Phase separation of nonionic surfactants in aqueous solutions was used to extract cadmium and zinc. After complexation with 6-(4-nitrophenyl)-2,4-diphenyl-3,5-diazabicyclo[3.1.0]hexene-2 (pH 1), cadmium and zinc were quantitatively transferred into the phase rich with the nonionic surfactant octylphenoxypolyethoxyethanol. After the addition of tetrahydrofuran and HCl to the extract, the elements were determined by flame atomic absorption spectrometry.     

Leaching of zinc and germanium from zinc oxide dust in sulfuric acid-ozone media

A new process of leaching zinc oxide dust by ozone oxidation in a sulfuric acid system was studied. The main factors affecting the leaching rate, such as ozone time, leaching temperature, initial acidity, leaching time, and liquid/solid mass ratio, were comprehensively investigated. The results show that leaching efficiency depends on all the above factors. The optimum conditions for leaching Zn and Ge from zinc oxide dust are as follows: ozone time 10 min, leaching temperature 90 ℃, initial acidity 160 g/L, leaching time 60 min, and liquid/solid mass ratio 7:1. Under the optimum conditions, the leaching rates of Zn and Ge are 95.79% and 93.65%, respectively. The leaching rates of zinc and germanium in the ozone leaching are 4.05% and 10.49% higher than those of the atmospheric leaching, respectively. Therefore, it is determined that ozone in solution plays a key role in rapidly oxidizing sulfide and releasing encapsulated germanium. Sulfuric acid-ozone media can efficiently extract Zn and Ge from zinc oxide dust.     

Determination of cadmium and bismuth in high-purity zinc metal by inductively coupled plasma mass spectrometry with on-line matrix separation

Traces of cadmium and bismuth in high-purity zinc metal were determined by inductively coupled plasma mass spectrometry (ICP-MS) in combination with flow injection (FI) on-line matrix separation (FI-ICP-MS). The anion-exchange separation method of the potassium iodide (KI) system was applied to the separation of the analytes from the matrix zinc. The analytes, cadmium and bismuth, were adsorbed on the anion-exchange (BIO. RAD AG1-X8) mini-column (1.0 mm i.d.x 100 mm bed length), while the matrix zinc can be completely removed from the anion-exchange resin. The analytes were eluted by 2 mol/l HNO(3) and directly introduced into the ICP-MS. The detection limits (D.L.) obtained by using a single injection (350 microl) were 0.81 and 0.075 ng g(-1) for cadmium and bismuth, respectively. In the case of multi-injection concentration onto the anion-exchange mini-column (five injections 350 microl each), the detection limits could be improved to 0.16 and 0.014 ng g(-1) for cadmium and bismuth, respectively. The reproducibilities of the single injection and the multi-injection method were satisfactory with a relative standard deviation of less than 5% (at the 10 and 1 ng ml(-1) level for the single injection and the multi-injection method, respectively). The method was successfully applied to the determination of trace impurities in four samples of high-purity zinc metal (7 nines grade) and three standard reference materials of high-purity unalloyed zinc samples (from NIST).     

Simultaneous Spectrophotometric Determination of Cadmium, Zinc and Copper with Kalman Filter

The compound 2-QADNm can form red complexes with caamium(II), zinc(II) and copper(II). The simultaneous determination of cadmium, zinc and copper with Kalman Filter is described in this paper, the proposed method was applied to a two-component system for determining cadmium and copper,and a three-component system for determining cadmium, zinc and copper.     

The X-ray fluorescence determination of Cd, Ni, and Zn electrodeposited from aqueous solutions

The concentrations of cadmium, nickel, and zinc in standard solutions were determined by energy-dispersive X-ray fluorescence analysis of deposits prepared by flow electrolysis on graphite cloth electrodes. Reduction of the metal species in solution was complete only if cadmium or zinc was the major constituent (80 or 90 mole%, respectively). Deposits of cadmium and zinc, and cadmium-rich Cd---Ni, Cd---Zn, and Cd---Ni---Zn deposits were analysed. For pure metals the detected X-ray intensity displayed a power-law relationship, Rn^p, for up to 10⁻⁴ moles. The enhancement effect of the cadmium on the nickel and zinc signals, and the absorption and enhancement effects between nickel and zinc, were corrected empirically. The absorption of cadmium X-rays by nickel and zinc was insignificant. Deposits of pure copper on heavier electrodes displayed similar fluorescent intensities.     

Fluorinated stannanes : Part 1. The stereospecific synthesis of fluorinated stannanes via a novel transmetalation of fluorinated zinc and cadmium reagents

Fluorinated stannanes are versatile synthetic intermediates. Reaction of fluorinated vinyl, alkyl and aryl zinc or cadmium reagents with tri-n-butyltin chloride at room temperature yielded the corresponding tri-n-butyl stannanes in moderate to excellent yields. The zinc or cadmium reagents also reacted efficiently with other trialkyl and triaryl chlorostannanes. These zinc and cadmium reagents were prepared in excellent yields by stirring the fluorinated halides with activated zinc or cadmium metal.     

利用旋风炉玻璃化处理垃圾焚烧飞灰实验研究

在自行设计的旋风炉实验台上对焚烧飞灰进行玻璃化熔融实验,系统研究了焚烧飞灰熔融前后微观形貌、灰渣中重金属特性和浸出特性。实验结果表明,焚烧飞灰旋风熔融后成黑色的脆硬玻璃态熔渣,表层呈浅黄色。在熔渣中N i、Cr的固溶率最高,均超过95%以上;低熔点重金属多数挥发至熔融烟气和熔融烟道飞灰颗粒中,Cd的固溶率仅有21%,Pb和Zn部分固溶于玻璃态熔渣中,两者固溶率可达42%以上。Cu和As的固溶率分别为37%和18%。熔融后的玻璃态熔渣重金属浸出率明显低于熔融前的焚烧飞灰,且均低于美国EPA的标准限值。     

Sequential extraction--spectrofluorometric determination of lead and cadmium using cryptands.

A spectrofluorimetric method for the determination of ultratrace amounts of lead and cadmium is described based on the sequential extraction of the ternary ion-association complexes formed between the cation, a cryptand as the ligand and eosin as a counter ion. A linear working range from the detection limit (0.5 ng ml(-1) to 250 ng ml(-1) of lead and to 1 50 ng ml(-1) of cadmium was obtained. The relative standard deviation was 2-4%. The proposed method has been applied successfully to the determination of lead and cadmium in zinc metals and soft drinks.     

Electrochemical and chemical syntheses,structures, and optical properties of the zinc and cadmium complexes in the N,N,O,S-ligand environment

The chemical and electrochemical syntheses of the zinc (I) and cadmium (II) complexes are carried out on the basis of the tridentate Schiff base (H₂L), the condensation product of (2-tosylaminoaniline) N-(2-aminophenyl)-4-methylbenzenesulfunamide with 1-phenyl-3-methyl-4-formylpyrazole-5-thiol. The structures and compositions of the synthesized metallochelates are proved by the data of C, H, and N elemental analyses, IR spectroscopy, and ¹H NMR spectroscopy. X-ray absorption spectroscopy is used to determine the structure of the zinc complex. The binuclear structure of the cadmium complex is confirmed by the X-ray diffraction data (CIF file CCDC no. 1471159). The optical properties of H₂L and the zinc and cadmium complexes in dimethyl sulfoxide (DMSO) solutions are studied.     

Anilinepropylsilica xerogel used as a selective Cu (II) adsorbent in aqueous solution

The metal ion adsorption properties of the microporous hybrid anilinepropylsilica xerogel were studied using divalent copper, zinc, and cadmium ions in aqueous solutions in concentrations ranging from 10(-4) up to 5x10(-3) moll(-1). At low concentrations the surface of the solid phase presents selectivity for Cu (II), even in competitive conditions. This preferential sorption ability for copper in relation to zinc and cadmium ions was interpreted by considering the xerogel morphology.