Palladium(II) sequestration by phytate in aqueous solution - speciation analysis and ionic medium effects

2010 ◽  
Vol 7 (3) ◽  
pp. 259 ◽  
Author(s):  
Antonio Gianguzza ◽  
Demetrio Milea ◽  
Alberto Pettignano ◽  
Silvio Sammartano
Keyword(s):  
Stability Constants ◽  
Urban Areas ◽  
Metal Ion ◽  
Empirical Relationship ◽  
Speciation Analysis ◽  
Stable Complex ◽  
Experimental Conditions ◽  
Complex Species ◽  
Ionic Medium ◽  
The Stability

Environmental context.In the last 20 years, the demand for palladium and other platinum-group elements has intensified, causing a significant increase in their concentration in the environment, with particular accumulation in urban areas. Knowledge about Pd2+ speciation in aqueous media is fundamental for the understanding of its biological and environmental activity in contaminated areas. Phytic acid appears to be a good sequestering agent towards Pd2+ under various conditions, indicating its potential use in the remediation of contaminated sites. Abstract. Palladium(II) speciation in the presence of phytate (Phy12–) was studied by H+ ion selective electrode (ISE) potentiometry at 25°C in NaNO3(aq) and in NaCl(aq) at ionic strength I = 0.1 mol L–1, in order to evaluate the effect of the ionic medium on the sequestering ability of phytate towards palladium(II). Owing to the discrepancies found in the literature on both the nature and the stability of hydrolytic species formed by this cation, Pd2+ hydrolysis was studied under the same experimental conditions as phytate/PdII measurements. As palladium(II) forms stable complex species with the chloride ion, the stability constants of various Pd2+–Cl– species were also calculated, as well as those of weak species formed with nitrate. The stability constants of six palladium(II)–phytate species, namely PdPhyOH11–, PdPhy10–, PdPhyH9–, PdPhyH28–, PdPhyH37– and PdPhyH46–, were determined. The sequestering ability of this ligand towards Pd2+ was evaluated by the calculation of various pL50 values (total ligand concentrations, as antilogarithm, necessary to bind the 50% of the metal ion as a trace present in the solution) under different conditions. Phytate sequestering ability towards palladium(II) was then compared with that towards other divalent cations under various conditions. Finally, the dependence of pL50 on pH was modelled by a simple empirical relationship.

The affinity of aldehydic compounds to complex formation. Nickel(II) and cobalt(II) complexes with 2-pyridinecarboxaldehyde

1977 ◽  
Vol 55 (14) ◽  
pp. 2613-2619 ◽  
Author(s):  
M. S. El-Ezaby ◽  
M. A. El-Dessouky ◽  
N. M. Shuaib
Keyword(s):  
Complex Formation ◽  
Aqueous Solutions ◽  
Stability Constants ◽  
Metal Ion ◽  
Experimental Conditions ◽  
Complex Species ◽  
Spectrophotometric Methods ◽  
Complex Equilibria ◽  
The Stability ◽  
Hydroxy Groups

The interactions of Ni(II) and Co(II) with 2-pyridinecarboxaldehyde have been investigated in aqueous solutions at μ = 0.10 M (KNO3) at 30 °C. The stability constants of different complex equilibria have been determined using potentiometric methods. Spectrophotometric methods were also used in the case of the nickel(II) – 2-pyridinecarboxaldehyde system. It was concluded that nickel(II) and cobalt(II), analogous to copper(II), enhance hyrdation of 2-pyridinecarboxaldehyde prior to deprotonation of one of the geminal hydroxy groups. Complex species of 1:1 as well as 1:2 metal ion to ligand composition exist under the experimental conditions used.

SODIUM CHELATES OF ETHYLENEDIAMINETETRAACETIC ACID

1963 ◽  
Vol 41 (1) ◽  
pp. 18-20 ◽  
Author(s):  
Vladimir Palaty
Keyword(s):  
Stability Constant ◽  
Stability Constants ◽  
Ethylenediaminetetraacetic Acid ◽  
Glass Electrode ◽  
Neutral Solution ◽  
Experimental Conditions ◽  
The Stability ◽  
Sensitive Method

The stability constant of the sodium chelate of EDTA was determined by means of a sodium-sensitive glass electrode. It appears that a hydrogen chelate of the formula NaHY2− is formed in the neutral solution of EDTA, but is very unstable. The stability constants, pKNaY = −2.61 and pKNaHY = 0.03, are comparable to the value obtained by Schwarzenbach and Ackermann under different experimental conditions by a less sensitive method.

Transferrin binding of Al3+ and Fe3+.

1987 ◽  
Vol 33 (3) ◽  
pp. 405-407 ◽  
Author(s):  
R B Martin ◽  
J Savory ◽  
S Brown ◽  
R L Bertholf ◽  
M R Wills
Keyword(s):  
Stability Constant ◽  
Blood Plasma ◽  
Stability Constants ◽  
Metal Ion ◽  
Equilibrium Dialysis ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Quantitative Studies ◽  
Intensity Changes ◽  
The Stability

Abstract An understanding of Al3+-induced diseases requires identification of the blood carrier of Al3+ to the tissues where Al3+ exerts a toxic action. Quantitative studies demonstrate that the protein transferrin (iron-free) is the strongest Al3+ binder in blood plasma. Under plasma conditions of pH 7.4 and [HCO3-]27 mmol/L, the successive stability constant values for Al3+ binding to transferrin are log K1 = 12.9 and log K2 = 12.3. When the concentration of total Al3+ in plasma is 1 mumol/L, the free Al3+ concentration permitted by transferrin is 10(-14.6) mol/L, less than that allowed by insoluble Al(OH)3, by Al(OH)2H2PO4, or by complexing with citrate. Thus transferrin is the ultimate carrier of Al3+ in the blood. We also used intensity changes produced by metal ion binding to determine the stability constants for Fe3+ binding to transferrin: log K1 = 22.7 and log K2 = 22.1. These constants agree closely with a revision of the reported values obtained by equilibrium dialysis. By comparison with Fe3+ binding, the Al3+ stability constants are weaker than expected; this suggests that the significantly smaller Al3+ ions cannot coordinate to all the transferrin donor atoms available to Fe3+.

scholarly journals Interaction of Ampicillin and Amoxicillin with Mn2+: A Speciation Study in Aqueous Solution

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3110
Author(s):  
Claudia Foti ◽  
Ottavia Giuffrè
Keyword(s):  
Aqueous Solution ◽  
Stability Constants ◽  
Metal Ion ◽  
Formation Constants ◽  
Enthalpy Change ◽  
Ligand Concentration ◽  
Empirical Parameter ◽  
Speciation Study ◽  
Potentiometric Measurements ◽  
The Stability

A potentiometric and UV spectrophotometric investigation on Mn2+-ampicillin and Mn2+-amoxicillin systems in NaCl aqueous solution is reported. The potentiometric measurements were carried out under different conditions of temperature (15 ≤ t/°C ≤ 37). The obtained speciation pattern includes two species for both the investigated systems. More in detail, for system containing ampicillin MLH and ML species, for that containing amoxicillin, MLH2 and MLH ones. The spectrophotometric findings have fully confirmed the results obtained by potentiometry for both the systems, in terms of speciation models as well as the stability constants of the formed species. Enthalpy change values were calculated via the dependence of formation constants of the species on temperature. The sequestering ability of ampicillin and amoxicillin towards Mn2+ was also evaluated under different conditions of pH and temperature via pL0.5 empirical parameter (i.e., cologarithm of the ligand concentration required to sequester 50% of the metal ion present in traces).

Fletcher–Powell minimization of analytical potentiometric data by microcomputer: application to the Cu(II) complexes of biological polyamines

1985 ◽  
Vol 63 (11) ◽  
pp. 3122-3128 ◽  
Author(s):  
Douglas M. Templeton ◽  
Bibudhendra Sarkar
Keyword(s):  
Biological Activity ◽  
Metal Complex ◽  
Stability Constants ◽  
Speciation Analysis ◽  
Complex Stability ◽  
Minimization Algorithm ◽  
The Stability ◽  
Best Fit ◽  
Complex Stability Constants ◽  
Potentiometric Data

The Fletcher–Powell minimization algorithm has been successfully implemented for the extraction of metal complex stability constants from analytical potentiometric data. The procedure has been adapted to run on a microcomputer with acceptable execution times, and several strategies are employed to speed convergence and avoid false minima. This allows economical minimization for a large number of models of speciation, and improves the reliability of the proposed best fit by encouraging the checking of more models than previously possible. The Ni(II)–glycine system has been analyzed and excellent agreement with the stability constants of an earlier multi-laboratory study has been attained. The system proves useful in the evaluation of both analytical and computational methods. The procedure has also been used for speciation analysis of the Cu(II) complexes of the growth regulating polyamines, spermine, and spermidine. Both systems form fully deprotonated complexes at physiological pH, which are relevant to their biological activity.

Predicting the Stability Constants of Metal-Ion Complexes from First Principles

2013 ◽  
Vol 52 (18) ◽  
pp. 10347-10355 ◽  
Author(s):  
Ondrej Gutten ◽  
Lubomír Rulíšek
Keyword(s):  
Stability Constants ◽  
First Principles ◽  
Metal Ion ◽  
Metal Ion Complexes ◽  
The Stability

Aqueous Reactions of Sparingly Soluble Tellurites I. Silver Tellurite

1972 ◽  
Vol 50 (11) ◽  
pp. 1788-1791 ◽  
Author(s):  
M. C. Mehra ◽  
S. M. Kahn
Keyword(s):  
Experimental Data ◽  
Stability Constant ◽  
Constant Temperature ◽  
Solubility Product ◽  
Complex Species ◽  
Ionic Medium ◽  
The Stability ◽  
Aqueous Reactions

The aqueous interactions of the sparingly soluble silver tellurite show that in a controlled ionic medium and at a constant temperature, an aqueous complex,[Formula: see text] is formed in presence of free tellurite ions. The solubility product of silver tellurite and the stability constant of the complex species have been evaluated from the experimental data.

scholarly journals IN SILICO MODEL QSPR FOR PREDICTION OF STABILITY CONSTANTS OF METAL-THIOSEMICARBAZONE COMPLEXES

2018 ◽  
Vol 127 (1A) ◽  
pp. 67
Author(s):  
Nguyen Minh Quang ◽  
Tran Xuan Mau ◽  
Pham Van Tat ◽  
Tran Nguyen Minh An ◽  
Vo Thanh Cong
Keyword(s):  
Neural Network ◽  
Stability Constants ◽  
In Silico ◽  
Metal Ion ◽  
Test Group ◽  
Structure And Property ◽  
The Neural Network ◽  
Complex Solutions ◽  
Artificial Neural Network Ann ◽  
The Stability

In the present work, the stability constants logb<sub>11</sub> and the concentration of metal ion and thiosemicarbazone in complex solutions were determined by using <em>in silico</em> models. The 2D, 3D, physicochemical and quantum descriptors of complexes were generated from the molecular geometric structure and semi-empirical quantum calculation PM7 and PM7/sparkle. The quantitative structure and property relationships (QSPRs) were constructed by using the ordinary linear regression (OLR) and artificial neural network (ANN). The best linear model QSPR<sub>OLR</sub> (with <em>k</em> of 6) involved descriptors k0, core-core repulsion, xp5, xch5, valence, and SHHBd. The quality of model QSPR<sub>OLR</sub> had the statistical values: <em>R</em><sup>2</sup><sub>train</sub> = 0.898, <em>R</em><sup>2</sup><sub>adj</sub> = 0.889, <em>Q</em><sup>2</sup><em><sub>LOO</sub></em> = 0.846, MSE = 1.136, and <em>F<sub>stat</sub></em> = 91.348. The neural network model QSPR<sub>ANN</sub> with architecture I(6)-HL(6)-O(1) had the statistical values: <em>R</em><sup>2</sup><em><sub>train</sub></em> = 0.9768, and <em>Q</em><sup>2</sup><em><sub>LOO</sub></em> = 0.8687. The predictability of QSPR models for complexes of the test group turned out to be in good agreement with those from the experimental data in the literature.

scholarly journals 1H NMR and spectrophotometric study of alkaline metal ion complexes with N-dansyl aza-18-crown-6

2006 ◽  
Vol 4 (1) ◽  
pp. 13-28 ◽  
Author(s):  
Tadeusz Ossowski ◽  
Hanna Sulowska ◽  
Tomasz Karbowiak ◽  
Dorota Zarzeczanska ◽  
Błażej Gierczyk ◽  
...  
Keyword(s):  
Fluorescence Spectroscopy ◽  
Stability Constants ◽  
Metal Ion ◽  
Spectrophotometric Study ◽  
Alkaline Metal ◽  
Empirical Methods ◽  
Absorption And Fluorescence Spectroscopy ◽  
The Stability ◽  
Semi Empirical ◽  
Formation Of Complexes

AbstractFormation of complexes of A18C6-Dns and metal cations (Ca2+, Sr2+, Ba2+ and Mg2+) in acetonitrile has been studied by NMR, absorption and fluorescence spectroscopy and PM5 semi-empirical methods. A18C6-Dns forms stable complexes with Ca2+, Sr2+ and Ba2+ cations. The stability constants of various complexes are determined by different methods and their structures are visualised by the PM5 semi-empirical calculations.

On the Hydrolysis of Tetravalent Metal Ions

2000 ◽  
Vol 663 ◽  
Author(s):  
C. Ekberg ◽  
P. Brown ◽  
J. Comarmond ◽  
Y. Albinsson
Keyword(s):  
Metal Ions ◽  
Stability Constants ◽  
Safety Assessment ◽  
Experimental Conditions ◽  
Polymeric Species ◽  
The Stability ◽  
Hydrolysis Of

ABSTRACTThe stability constants of the hydroxide complexes of zirconium(IV) and uranium(IV) have been measured at 15, 25 and 35°C [in 1.0 mol dm−3 (Na, H)ClO4] using potentiometry. For zirconium(IV), the results indicate the presence of Zr(OH)3+ and the polymeric species Zr3(OH)48+ and Zr4(OH)88+ whereas the results for uranium(IV) indicate the presence of U(OH)3+ and the polymeric species U4(OH)124+. The hydrolysis of both metal ions was studied at three temperatures allowing the determination of ΔH° and ΔS° of reaction for each species. The results were compared with previous results determined for thorium(IV) under the same experimental conditions to ascertain whether thorium should be used as an analogue for other tetravalent metal ions in safety assessment studies of nuclear repositories.

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