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Specrophotometric study and analytical applications of the complexes of copper(II) and zinc(II) with some sulphonated azo-dyes
No full textThe complexing ability of some sulphonated azo-dyes towards copper(II) and zinc(II) were investigated in different conditions. One of the considered ligands was able to complex only copper(II), so allowing a very good selectivity to be obtained
VOLTAMMETRIC DETERMINATION OF SOME ORGANIC COMPOUNDS OF ARSENIC REDUCED AT THE MERCURY ELECTRODE
No full textCyclic voltammetric scans for methylarsonic acid, dimethylarsinic acid and 3-acetamido-4-hydroxyphenylarsonic acid at amercuryelectrode in an acidic medium show anodic adsorption waves when the starting potential is sufficiently negative; the related arsines are formed on the electrode. Detection limits are at the micromolar level for the absorption peak found at about −0.1 V vs. SCE for all three compounds. Interferences are discussed
Spectrophotometric investigation of the reactions of nickel(II) with some sulphonated azo-dyes
No full textSix azo-dyes, synthesized in our laboratory or commercially available, containing or not containing heteroatoms, have been investigated for their complexation properties towards nickel(II). As a result, a spectrophotometric method for Ni(II) determination could be developped
Determination of total and free copper(II) and cadmium(II) in freshwater samples by chelating resin titration with a resin containing iminodiacetic groups
No full textThe sorption of copper(II) and cadmium(II) on a chelating resin containing iminodiacetic groups from freshwater samples by a batch procedure is investigated. As in most cases sorption is not quantitative, a method is suggested for the evaluation of total concentration, based on the determination of the concentration of the metal ion sorbed on the resin at different values of the ratio V/w, i.e. the volume of the solution phase to the amount of resin. The method is named chelating resin titration (CRT). A good agreement was found between the total concentration of the metal ion in the sample and that found by CRT. The ratio of total to free metal ion (alpha(M(I))) in solution in the presence of the resin could be evaluated by the same procedure, obtaining very high values at the two acidities considered, and for both metal ions. The usual complexing substances commonly present in freshwaters can not be considered responsible for such strong complexation
Investigation of the Complexation of Metal-Ions by Strong Ligands in Fresh and Marine Water.
No full text1. Scope. The detection and investigation of metal ions bound in strong complexes in natural waters is a difficult task, due to the low concentration of the metal ions themselves, and also of the
strong ligands, which, moreover, are often not of a well-defined
composition. Here, a method is proposed for the investigation
of the speciation of metal ions in natural waters.
2. Objective and Method. It is based on the sorption of metal ions
on strongly sorbing ion exchange resins, i.e. complexing resins.
For this reason the method is called Resin Titration. It has been
shown in previous investigations that the concentration of metal
ion totally sorbed by a particular resin, and its reaction coefficient
in the solution phase in the presence of the resin, can be
determined from the sorption data using a simple relationship.
Here, a data treatment (the Ruzic linearization method) is proposed for also determining the concentration of the ligands responsible for the complex in equilibrium with the resin.
3. Results. The method was applied to data obtained by Resin Titration of a freshwater and a seawater. Copper(II) and aluminium(III) were considered, using Chelex 100 as a titrant, due to its strong sorbing properties towards these metal ions. The results were: the total metal concentration in equilibrium with the resin, the side reaction coefficients, and the concentration of ligands. In all these cases the ligands forming very strong complexes were found to be at concentration lower than that of the metals.
4. Conclusion. The Ruzic linearization method allows the determination of the concentration of the ligands forming very
strong complexes in equilibrium with Chelex 100. The reaction
coefficient was better determined by the calculation method
previously proposed for RT. The ligands responsible for the
strong complexes were found to be at low concentration, often
lower than that of the metal ions considered. The metal in the
original sample is partly bound to these ligands, since the complexes are very strong. Only a part of the metal is linked to
weaker ligands, or free
The reaction between tetrazolazo-2-naphhol-3,6-disulphonic acid and Cu(II) and Ni(II). Analytical application
No full textDiffusione di inquinanti in relazione alla presenza di discariche abusive. Esempi dell'Oltrepo pavese.
No full textApplied macroinorganics. IV. Effect of the crosslinking agent on protonation and metal ions complexing abilities of ion exchange resins with poly(amido-amine) structure
No full textOscillopolarographic determination of cyanide in waste electroplating industrial effluents
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