Direct electrochemical synthesis of cobalt,nickel, copper,zinc, cadmium,tin and lead zincon complexes

Transition Metal Chemistry - Main group and transition metal complexes of zincon-(2-hydroxy-5-sulphonyl azobenzylidene hydrazinobenzoic acid) have been prepared by an electrochemical technique...     

Spectrophotometric study of cobalt, nickel, copper, zinc, cadmium and lead complexes with murexide in dimethylsulphoxide solution

The complexation reactions between murexide and Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+) and Pb(2+) ions have been studied spectrophotometrically in dimethylsulphoxide solution at 25 degrees . The stoichiometry of the complexes was found to be 1:1. The stability constants of the complexes were determined, and found to follow the Irving-Williams rule for the cations of the first transition series. In dimethylsulphoxide solution, the complexes are much more stable than those in aqueous solution.     

High-performance liquid chromatographic separation of hematoporphyrin and its nickel,copper and zinc complexes on octadecyl-bonded stationary phase

Summary The feasibility of reversed-phase high-performance liquid chromatography for the separation of metal complexes of hematoporphyrin IX (Hp) is described. The retention order, Zn-complex<Hp (free acid)< Ni-complex<Cu-complex, is regular on an octadecylbonded stationary phase with different compositions of an aqueous methanol mobile phase. These four compounds can be successfully separated within about 8 min on a LiChrosorb RP-18 column (250×4-mm i.d.) with a 85:15 (vol/vol) mixture of methanol and phosphate buffer (pH 3) at a flow rate of 1 ml/min.     

Cold ultrasonic acid extraction of copper, lead and zinc from soil samples

A cold ultrasonic acid method for extracting Pb, Cu and Zn from soil samples has been studied. This work focused on studying the experimental condition for extrating trace metals from soil samples at ambient temperature (≈25 °C) using Syrian soil samples; the same conditions were applied to reference soil samples(SL-1, Soil-7, SDM, and BCR-32). A short exposure time (4 h), and 2 ml of concentrated hydrochloric acid were found to be best. Under the applied conditions Pb, Cu and Zn were quantitavely extracted, while Sr, Mn, Fe, Al, Cr, Co, and Ni were partialy extracted. The advantages of the cold ultrasonic extraction method are as follows: it is selective, it is matrix free, the extraction time is short, the amounts of consumed chemicals are small, the by-products of the process are negligible and it is environmentally clean, since no fume emissions are emitted. The only disadvantage is that it is not a real total digestion method. Comparable results for the proposed ultrasound method and the hot-plate acid digestion method for Cu, Pb and Zn in certified refrence soil samples(SL-1, SDM, Soil-7, BCR-32, Soil-6) and some Syrian soil samples are obtained.     

Cation-exchange separation of hafnium and zirconium from accompanying ions

Hafnium and zirconium are not retained on the strongly acidic cation-exchange resin Dowex 50 from a mixture consisting of methanol and 12M nitric acid (19:1) which is 0.1M in trioctylphosphine oxide. On the other hand most other elements investigated are strongly adsorbed on the resin from this medium so that they are readily separated from hafnium and zirconium. These elements include titanium, rare earths, alkali metals, alkaline earth metals, iron, cobalt, manganese and zinc. This separation technique has been found to be suitable for the separation of tracer and milligram amounts of hafnium and zirconium from accompanying metal ions. If in place of methanol other organic solvents such as acetone, tetrahydrofuran and methyl glycol are used the selectivity of the separation of zirconium and hafnium from the other elements is decreased. The same effect is observed when hydrochloric acid is used in the mixtures instead of nitric acid.     

Coprecipitation with yttrium phosphate as a separation technique for iron(III), lead, and bismuth from cobalt, nickel, and copper matrices

The coprecipitation behavior of 44 elements (47 ions because of chromium(III,VI), arsenic(III,V), and antimony(III,V)) with yttrium phosphate was investigated at various pHs. Yttrium phosphate could quantitatively coprecipitate iron(III), lead, bismuth, and indium over a wide pH range; however, 18 ions, including alkali metals and oxo anions, such as vanadium(V), chromium(VI), molybdenum(VI), tungsten(VI), germanium(IV), arsenic(III,V), selenium(IV), and tellurium(VI), were scarcely collected. In addition, 19 ions, including cobalt, nickel, and copper(II), were hardly coprecipitated at pHs below about 3. Based on these results, the separation of iron(III), lead, and bismuth from cobalt, nickel, and copper(II) matrices was investigated. Iron(III), lead, and bismuth ranging from 0.5 to 25 μg could be separated effectively from a solution containing 0.5 g of cobalt, nickel, or copper at pH 3.0. The separated iron(III), lead, and bismuth could be determined by inductively coupled plasma atomic emission spectrometry using internal standardization. The detection limits (3σ, n = 7) of iron(III), lead, and bismuth were 0.008, 0.137, and 0.073 μg, respectively. The proposed method was applied to the analyses of metals and chlorides of cobalt, nickel, and copper.     

Complexes of nitrilotrimethylphosphonic acid with cobalt, nickel, copper and zinc

Substances of the types MH₄ntmp, Mg₃[M(Hntmp)]₂, M₂H₂ntmp and Mg[M₂(Hntmp)]₂, where M = Co, Ni, Cu, Zn and H₆ntmp = N[CH₂PO(OH)₂]₃ were prepared. The sodium and cesium salts of the [Co(Hntmp)]³⁻ complexes were also prepared. The IR and electronic spectra and the experimental magnetic susceptibilities indicate that these are high-spin complexes. The coordination surroundings of the central atom consist of a highly distorted octahedron of the ligand oxygen atoms. The nitrogen atom is not coordinated to the central atom.     

Electrothermal atomic absorption spectrometric determination of cobalt, copper, lead and nickel traces in aragonite following flotation and extraction separation

A method of determination of Co, Cu, Pb and Ni in nanogram quantities from aragonite is presented. Flotation and extraction of Co, Cu, Pb and Ni is suggested as methods for elimination matrix interferences of calcium. The method of flotation is performed by iron(III) hexamethylenedithiocarbamate, Fe(HMDTC)(3), as a colloid precipitate collector. The liquid-liquid extraction of Co, Cu, Pb and Ni is carried out by sodium diethyldithiocarbamate, NaDDTC, as complexing reagent into methylisobutyl ketone, MIBK. The electrothermal atomic absorption spectrometry (ETAAS) is used for determination of analytes. The detection limits of ETAAS followed by flotation are: 7.8 ng.g(-1) for Co, 17.1 ng.g(-1) for Cu, 7.2 ng.g(-1) for Pb and 9.0 mug.g(-1) for Ni. The detection limits of ETAAS followed by extraction are found to be: 12.0 ng.g(-1) for Co, 51.0 ng.g(-1) for Cu, 24.0 ng.g(-1) for Pb and 21.0 ng.g(-1) for Ni.     

Column separation and preconcentration of copper(II), lead(II) and zinc(II) from seawater

Summary The sample of seawater (51) is freed from solid particles, buffered at pH 5.6 and percolated through a column filled with ED₃A. After sample passage 15 ml 1 M hydrochloric acid solution are pumped through the column to dissolve the concentrated ions. The final measurement using flame atomic absorption is carried out in the hydrochloric acid solution. The total labour time is less than 15 min. The standard deviations (4 analyses) for the determination of Cu, Pb and Zn (in the normal concentration range of 2–6 g · l^–1) were 2–5%, 5% and 1–10%, the recoveries 100%, 102% and 104%, respectively. A concentration coefficient of 300–500 was obtained.On leave from Lisbon University, Portugal     

Selective extractive separation of zinc, cadmium and lead from iodide media with mesityl oxide

The extractive separation of zinc, cadmium and lead with mesityl oxide has been investigated as a function of iodide concentration and acidity. The recovery of these metals from the organic phase by back-extraction and the behaviour of other elements under the optimal conditions established for each metal ion have been examined. The method developed has been applied to the separation of these metals from rock samples before determination by spectrophotometry.     

Chitosan for the collection from seawater of naturally occurring zinc, cadmium, lead and copper

Anodic stripping voltammetry with a composite graphite-mercury electrode was applied in order to demonstrate that chitosan can collect naturally occurring zinc, cadmium, lead and copper from sea-water, with high yields. Chitosan columns (15 x 10mm) can be used to preconcentrate trace metals from 3 1. of sea-water; the four elements can be selectively eluted with electrolytes suitable for conventional polarographic determinations. The method can find application in sea-water pollution survey and detection.     

Preconcentration of copper, nickel and zinc with Amberlite XAD-16 resin

Summary An adsorption-elution and atomic absorption spectrophotometric method using Amberlite XAD-16 is proposed for the preconcentration and determination of Cu, Ni and Zn. Optimum conditions for the preconcentration were investigated. Recoveries of the elements were found to be 82.4±0.3%, 95±3% and 71±1% for Cu, Zn and Ni, respectively, at 95% confidence level. The recoveries were increased to about 99% for Cu and Ni by complexing with 1-(2-pyridylazo)-2-naphthol (PAN). The effect of Na and K on the preconcentration of trace metals has also been investigated. The method was applied to a tap water.     

Changes in copper, lead and zinc concentrations in plants from paper mill sludge-treated soils

Effects of paper mill sludge addition on the availability of metals were studied on different soils both laboratory and naturally polluted; copper, lead and zinc concentrations were determined in Hordeum Distichum plants grown on the untreated and on sludge-treated soils. In some case a decrease of metal concentration is observed on sludge-treated soils; these results are consistent with the reduction of metal mobile forms in the soil, before plant growth. The decrease of metal availability in sludge-treated soils may be related with the pH value of the soil after sludge addition.     

Sorption of lead, copper, cadmium, zinc, and nickel by marine algal biomass: characterization of biosorptive capacity and investigation of mechanisms

The marine algae Sargassum sp., Padina sp., Ulva sp., and Gracillaria sp., harvested locally, were investigated for their biosorption performance in the removal of lead, copper, cadmium, zinc, and nickel from dilute aqueous solutions. It was found that the biosorption capacities were significantly affected by solution pH, with higher pH favoring higher metal-ion removal. Kinetic and isotherm experiments were carried out at the optimal pH: at pH 5.0 for lead and copper, and at pH 5.5 for cadmium, zinc, and nickel. The metal removal rates were rapid, with 90% of the total adsorption taking place within 60 min. Sargassum sp. and Padina sp. showed the highest potential for the sorption of the metal ions, with the maximum uptake capacities ranging from 0.61 to 1.16 mmol/g for Sargassum sp. and 0.63 to 1.25 mmol/g for Padina sp. The general affinity sequence for Padina sp. was Pb>Cu>Cd>Zn>Ni, while that for Sargassum sp. was Pb>Zn>Cd>Cu>Ni. XPS and FTIR analysis of Sargassum sp. and Padina sp. revealed the chelating character of the ion coordination to carboxyl groups. It was confirmed that carboxyl, ether, alcoholic, and amino groups are responsible for the binding of the metal ions.