Chemical speciation in fresh, saline and hyper-saline waters

2014 ◽  
Vol 86 (7) ◽  
pp. 1097-1104 ◽  
Author(s):  
Stefka Tepavitcharova ◽  
Diana Rabadjieva ◽  
Tihomir Todorov ◽  
Antonina Kovacheva ◽  
Manos Dassenakis ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Natural Waters ◽  
Chemical Species ◽  
Interaction Model ◽  
Ion Association ◽  
Water Systems ◽  
Association Model ◽  
Combined Model ◽  
Inorganic Composition ◽  
The Stability

AbstractA thermodynamic model is proposed, which combines the ion association and the ion interaction models using the extended database pit2010.dat for a more precise modeling of the chemical species of micro components in natural waters of varying ionic strength (fresh, saline and hyper-saline). Compared to the ion association model, the proposed combined model more adequately describes the complex character of the ionic interactions. The performance of the combined ion association/ion interaction model compared to that of the ion association model is illustrated in case studies of several Bulgarian natural water systems of different ionic strength and type of pollution. The results are interpreted in terms of the chemical behavior of the metals and of their chemical species in the water systems, which is defined by the redox potential, pH, cationic and anionic organic and inorganic composition of the water systems and by the ability of the metals to preferentially coordinate with some anions, as well as by the stability of the corresponding species. The affinity of the transition metals towards the ligands is explained by the “hardness-softness” factor and the crystal field stabilization energy (CFSE).

Investigation of V(V) interaction with Humic Acid in aqueous solution using anion-exchange Ion Chromatography

2021 ◽  
Author(s):  
Lucija Knežević ◽  
Elvira Bura-Nakić
Keyword(s):  
Humic Acid ◽  
Ionic Strength ◽  
Anion Exchange ◽  
Ion Chromatography ◽  
Natural Waters ◽  
Detection System ◽  
Chemical Species ◽  
Research Report ◽  
Complexing Agent ◽  
Model Solutions

<p>The distribution of V chemical species in natural waters has been scarcely studied mainly due to its high reactivity and wide variety of co-existing forms depending on number of factors including metal concentration, pH, Eh, ionic strength, the presence of complexing ligands etc. <sup>1</sup> Importance of V speciation studies lies in the dependence of toxicity and bioavailability upon different chemical species that V takes form of in natural waters, with V(V) being most toxic and soluble <sup>4</sup>. Although thermodynamic calculations predict V(V) as dominant species in well oxidized marine environments, V(IV) is also reported to be present due to its ability to form stable complexes with Dissolved Organic Matter (DOM) related ligands found in natural waters <sup>2–6</sup>. Furthermore, previous research report that Humic Acid (HA) acts as an adsorbent and complexing agent for many trace metals (Cu<sup>2+</sup>, Zn<sup>2+</sup>, Cd<sup>2+</sup>, Fe<sup>2+</sup>). However, HA impact on V speciation and potential removal from the water column of natural aquatic systems is still unclear <sup>7</sup>.</p><p>Interaction of V(V) with HA was investigated in model solutions under different conditions using anion-exchange based Ion Chromatography with UV/Vis detection system. The goal of the research was to mimic natural conditions, as experimentally possible, in order to assess likely contribution of HA to changes in V speciation and potential removal from the solution by adsorption on HA colloids. Temporal study on V(V) reduction kinetics was conducted using strong chelator (EDTA) which was added in the filtrated solution prior to measurement in order to stabilize distribution of V species in the model solutions. Removal of V(V) from the solution on HA particles was quantified using calibration curves. Desorption experiments were performed with the addition of EDTA in un-filtrated solutions 24 hours before measurement.</p><p>Research showed that V interaction with HA is highly dependant on ionic strength of solution as well as ratios between V(V) and HA present in the solution. Desorption experiments showed almost complete recovery of V in the solutions with higher ionic strength, mainly in the form of V(IV). Observed reduction and removal of V(V) from the solution on the pH of natural waters suggest high impact of DOM on V speciation and consequently its toxicity and bioavailability.  </p><p><strong>References:</strong></p><p>1           P. N. Linnik and R. P. Linnik, Russ. J. Gen. Chem., 2018, <strong>88</strong>, 2997–3007.</p><p>2           J. P. Gustafsson, Appl. Geochemistry, 2019, <strong>102</strong>, 1–25.</p><p>3           P. Bernárdez, N. Ospina-Alvarez, M. Caetano and R. Prego, Environ. Chem., 2013, <strong>10</strong>, 42–53.</p><p>4           D. Wang and S. A. Sañudo Wilhelmy, Mar. Chem., 2009, <strong>117</strong>, 52–58.</p><p>5           K. Hirayama, S. Kageyama and N. Unohara, Analyst, 1992, <strong>117</strong>, 13–17.</p><p>6           D. Wang and S. A. Sañudo-Wilhelmy, Mar. Chem., 2008, <strong>112</strong>, 72–80.</p><p>7           Y. Yu, M. Liu and J. Yang, Chem. Ecol., 2018, <strong>34</strong>, 548–564.</p>

Europium tartronate and mandelate ion association in water

1967 ◽  
Vol 45 (14) ◽  
pp. 1643-1647 ◽  
Author(s):  
P. G. Manning
Keyword(s):  
Ionic Strength ◽  
Solvent Extraction ◽  
Stability Constant ◽  
Stability Constants ◽  
Ion Association ◽  
Tridentate Ligand ◽  
Radiotracer Method ◽  
The Stability ◽  
Two Stages ◽  
Low Ionic Strength

Stepwise stability constants have been determined for the 1:1 and 1:2 Eu3+:mandelate− and Eu3+:tartronate2− complexes in water. Measurements were made at low ionic strength and the temperature was 25 °C. The solvent-extraction–radiotracer method was used.For the mandelate system at an ionic strength of 0.104, K1 = 5.0 × 102, K2 = 1.58 × 102, and K1:K2 = 3.1. The K1:K2 ratios suggest monodentate ligandcy.The stepwise stability constants for the two stages of tartronate ion association are: K1 = 7.1 ( ± 15%) × 104 and K1K2 = 4.2 ( ± 5%) × 108. The magnitudes of the stability constants suggest that tartronate is a tridentate ligand. The stability constant ratios are discussed with reference to the ratios for piperidinedicarboxylate and iminodiacetate complexes.

Aggregation kinetics and surface charge of CuO nanoparticles: the influence of pH, ionic strength and humic acids

2013 ◽  
Vol 10 (4) ◽  
pp. 313 ◽  
Author(s):  
Vânia Serrão Sousa ◽  
Margarida Ribau Teixeira
Keyword(s):  
Ionic Strength ◽  
Surface Charge ◽  
Humic Acids ◽  
Electrostatic Interactions ◽  
Natural Waters ◽  
Particle Diameter ◽  
Cuo Nanoparticles ◽  
Hydrodynamic Diameter ◽  
Aggregation Kinetics ◽  
The Stability

Environmental context The high demand and use of nanomaterials in commercial products have led to increased concerns about their effect on the environment and human health. Because CuO nanoparticles are widely used in several products, it is necessary to understand and predict their behaviour and fate in the environment. We report a study on the aggregation and surface charge of CuO nanoparticles under environmentally relevant conditions to better predict the mobility and bioavailability of these materials in natural waters. Abstract In this study, the role of pH, ionic strength and humic acids (HAs) on the aggregation kinetics and surface charge of commercial copper oxide (CuO) nanoparticles were examined. Results show that the aggregation of CuO nanoparticles is favoured near pH 10, which was determined as the isoelectric point where the hydrodynamic diameter of the aggregates is the greatest. The aggregation of CuO nanoparticles is also ionic strength dependent. The increase in the ionic strength reduces the zeta potential, which leads to an increase in aggregation until 0.15M. After this point an increase in ionic strength has no influence on aggregation. In the presence of HA for concentrations below 4mgCL–1, aggregation was enhanced for acidic to neutral pH, whereas for higher concentrations, at all pH tested, aggregation does not change. The influence of HA on CuO nanoparticles is due to steric and electrostatic interactions. The sedimentation rates of CuO nanoparticles showed a relation between particle diameter and zeta potentials values confirmed by Derjaguin–Landau–Verwey–Overbeek calculations. The results obtained have important implications for predicting the stability and fate of CuO nanoparticles in natural water.

TARTRATE COMPLEXES OF THE RARE-EARTH ELEMENTS II. THE dl- AND meso-TARTRATE COMPLEXES OF La, Ce, Pm, Tm, AND Y

1963 ◽  
Vol 41 (10) ◽  
pp. 2566-2574 ◽  
Author(s):  
P. G. Manning
Keyword(s):  
Rare Earth ◽  
Ionic Strength ◽  
Stability Constant ◽  
Metal Ion ◽  
Ionic Radius ◽  
Ion Association ◽  
Liquid Distribution ◽  
Distribution Method ◽  
The Stability ◽  
Two Stages

The liquid-liquid distribution method has been used to measure the stability constants of the dl-tartrate complexes of La3+, Ce3+, Pm3+, Tm3+, and Y3+, and the meso-tartrate complexes of Ce3+ and Tm3+. Thenoyltrifluoroacetone was the organic phase extractant, and the aqueous phase, acetate buffered (pH = 4.53), was maintained at a constant ionic strength (0.0597) by means of sodium perchlorate.The order of stabilities for the two stages of ion association are[Formula: see text][Formula: see text]The b1/b2 values, where b is a stepwise stability constant defined as [Formula: see text]are lower (by factors of 4–8) for the dl-tartrates than for the meso-tartrate complexes. The b1/b2 ratios decrease as the ionic radius of the metal ion decreases, and for the dl-tartrates of Tb3+, Y3+, and Tm3+, the b1/b2 values are 5.3, 5.0, and 4.3 respectively. The enhanced stabilities of the 1:2 (ML2−) dl-tartrate chelates have been interpreted in terms of ligand–ligand hydrogen bridging in the 1:2 complex.

EUROPIUM OXALATE ION ASSOCIATION IN WATER

1966 ◽  
Vol 44 (24) ◽  
pp. 3057-3062 ◽  
Author(s):  
P. G. Manning
Keyword(s):  
Acetic Acid ◽  
Ionic Strength ◽  
Stability Constant ◽  
Stability Constants ◽  
Aqueous Phase ◽  
Sodium Acetate ◽  
Ion Association ◽  
Sodium Oxalate ◽  
Aqueous Sodium ◽  
Oxalate Ion

The partitioning of radiotracer 152/151Eu between aqueous sodium oxalate (Na2L) solutions and toluene solutions of thenoyltrifluoroacetone (HTTA) has been studied as a function of the oxalate concentration. The pH of the aqueous phase was controlled by means of sodium acetate – acetic acid mixtures and the ionic strength (I) by NaCl or NaClO4.At low ionic strengths (~0.05) and [L] ~10−4 M EuL+ formed, but at I = 0.95 and [L] ~10−3 M EuL2− also formed. Stability constants for the 1:1 and 1:2 (metal:ligand) complexes are reported.The magnitudes of the stepwise stability constant ratios are discussed.

Thermodynamic Studies of the Core Histones:  pH and Ionic Strength Effects on the Stability of the (H3−H4)/(H3−H4)2System†

Biochemistry ◽  
1996 ◽  
Vol 35 (6) ◽  
pp. 2037-2046 ◽  
Author(s):  
Vassiliki Karantza ◽  
Ernesto Freire ◽  
Evangelos N. Moudrianakis
Keyword(s):  
Ionic Strength ◽  
Thermodynamic Studies ◽  
The Core ◽  
Core Histones ◽  
The Stability

scholarly journals Stability Studies of Transition Metal Chelates of 5-Bromosalicylidene-4-methoxyaniline andSalicylidene-2,3-dimethylaniline as Ligands

2011 ◽  
Vol 8 (4) ◽  
pp. 1911-1915
Author(s):  
N. G. Nadkarni ◽  
K. V. Mangaonkar
Keyword(s):  
Ionic Strength ◽  
Transition Metal ◽  
Stability Constants ◽  
Metal Chelates ◽  
Ternary Complexes ◽  
Water Medium ◽  
Stability Studies ◽  
Binary And Ternary Complexes ◽  
Transition Metal Chelates ◽  
The Stability

Binary and ternary complexes of the type M-Y and M-X-Y [M = Mn(II), Ni(II), Cu(II) and Zn(II); X = 5-bromosalicylidene-4-methoxyaniline and Y = salicylidene-2,3-dimethylaniline] have been examined pH-metrically at 27±0.5°C and at constant ionic strength, μ = 0.1 M (KCl) in 75 : 25(v/v) 1,4-dioxne-water medium. The stability constants for binary (M-Y) and ternary (M-X-Y) systems were calculated.

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