Modeling the acid-base properties of molybdate(VI) in different ionic media, ionic strengths and temperatures, by EDH, SIT and Pitzer equations

Crea, Francesco; Stefano, Concetta De; Irto, Anna; Milea, Demetrio; Pettignano, Alberto; Sammartano, Silvio

doi:10.1016/j.molliq.2016.12.041

Cited by 20 publications

(12 citation statements)

References 41 publications

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“…The rationale behind this choice was that p 2 , dependent on I 2 , accounts for the C Φ and Ψ coefficients in classical Pitzer equations, which can usually be neglected at relatively low ionic strengths (usually at I < 1 mol kg −1 ). Moreover, it is known that classical Pitzer coefficients are very highly correlated, so that their simultaneous refinement dramatically increases the risk of overparametrization [64]. That is why, when possible, and when no statistically significant improvements of fit quality can be obtained, it is preferable to reduce the number of Pitzer coefficients that are calculated, as was done in this work.…”

Section: Ionic Strength Dependencementioning

confidence: 99%

“…The dependence of the formation constants on ionic strength was studied by means of different approaches, namely the extended Debye-Hückel (EDH), specific ion interaction theory (SIT), and Pitzer approaches (general information can be found, e.g., in References [40][41][42][43][44][45][46], while for some examples of their applications one can refer to [64,[77][78][79][80]).…”

Section: Dependence On Ionic Strengthmentioning

confidence: 99%

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Understanding the Solution Behavior of Epinephrine in the Presence of Toxic Cations: A Thermodynamic Investigation in Different Experimental Conditions

et al. 2020

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The interactions of epinephrine ((R)-(−)-3,4-dihydroxy-α-(methylaminomethyl)benzyl alcohol; Eph−) with different toxic cations (methylmercury(II): CH3Hg+; dimethyltin(IV): (CH3)2Sn2+; dioxouranium(VI): UO22+) were studied in NaClaq at different ionic strengths and at T = 298.15 K (T = 310.15 K for (CH3)2Sn2+). The enthalpy changes for the protonation of epinephrine and its complex formation with UO22+ were also determined using isoperibolic titration calorimetry: ΔHHL = −39 ± 1 kJ mol−1, ΔHH2L = −67 ± 1 kJ mol−1 (overall reaction), ΔHML = −26 ± 4 kJ mol−1, and ΔHM2L2(OH)2 = 39 ± 2 kJ mol−1. The results were that UO22+ complexation by Eph− was an entropy-driven process. The dependence on the ionic strength of protonation and the complex formation constants was modeled using the extended Debye–Hückel, specific ion interaction theory (SIT), and Pitzer approaches. The sequestering ability of adrenaline toward the investigated cations was evaluated using the calculation of pL0.5 parameters. The sequestering ability trend resulted in the following: UO22+ >> (CH3)2Sn2+ > CH3Hg+. For example, at I = 0.15 mol dm−3 and pH = 7.4 (pH = 9.5 for CH3Hg+), pL0.5 = 7.68, 5.64, and 2.40 for UO22+, (CH3)2Sn2+, and CH3Hg+, respectively. Here, the pH is with respect to ionic strength in terms of sequestration.

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Section: Ionic Strength Dependencementioning

confidence: 99%

Section: Dependence On Ionic Strengthmentioning

confidence: 99%

Understanding the Solution Behavior of Epinephrine in the Presence of Toxic Cations: A Thermodynamic Investigation in Different Experimental Conditions

et al. 2020

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“…For an accurate determination of the stability constants of (MoO 4 ) p ( 8-HQA ) q H r (2p+2q−r)− complexes, the acid–base properties of both MoO 4 2− and 8-HQA should be known in the exact conditions of the experiments. Protonation constants at T = 298.15 K and I = 0.2 mol·dm −3 in KCl (aq) were taken from previous works for both ligands [ 2 , 30 ], and are reported as supplementary information (Table S1) . Furthermore, in order to analyze data from spectrophotometric measurements, the specific molar absorbances of both the free ligands and their protonated species must be also known, to be added as input in HypSpec2014 software.…”

Section: Resultsmentioning

confidence: 99%

“…Uncertainties are reported at the ±95% confidence interval. were taken from previous works for both ligands [2,30], and are reported as supplementary information (Table S1). Furthermore, in order to analyze data from spectrophotometric measurements, the specific molar absorbances of both the free ligands and their protonated species must be also known, to be added as input in HypSpec2014 software.…”

Section: Thermodynamic Calculationsmentioning

confidence: 99%

8-Hydroxyquinoline-2-Carboxylic Acid as Possible Molybdophore: A Multi-Technique Approach to Define Its Chemical Speciation, Coordination and Sequestering Ability in Aqueous Solution

et al. 2020

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8-hydroxyquinoline-2-carboxylic acid (8-HQA) has been found in high concentrations (0.5–5.0 mmol·dm−3) in the gut of Noctuid larvae (and in a few other lepidopterans), in which it is proposed to act as a siderophore. Since it is known that many natural siderophores are also involved in the uptake and metabolism of other essential elements than iron, this study reports some results on the investigation of 8-HQA interactions with molybdate (MoO42−, i.e., the main molybdenum form in aqueous environments), in order to understand the possible role of this ligand as molybdophore. A multi-technique approach has been adopted, in order to derive a comprehensive set of information necessary to assess the chemical speciation of the 8-HQA/MoO42− system, as well as the coordination behavior and the sequestering ability of 8-HQA towards molybdate. Chemical speciation studies have been performed in KCl(aq) at I = 0.2 mol·dm−3 and T = 298.15 K by ISE-H+ (glass electrode) potentiometric and UV/Vis spectrophotometric titrations. CV (Cyclic Voltammetry), DP-ASV (Differential Pulse-Anodic Stripping Voltammetry), ESI-MS experiments and quantum mechanical calculations have been also performed to derive information about the nature and possible structure of species formed. These results are also compared with those reported for the 8-HQA/Fe3+ system in terms of chemical speciation and sequestering ability of 8-HQA.

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“…Cruywagen et al 43,44 determined experimentally the formation constants of several medium-sized polyoxomolybdates involved in the formation of octamolybdate [Mo 8 O 26 ] 4À . Further work has been done in that direction, including measurements that combine potentiometric 45 and spectroscopic 46,47 techniques. These sets of experimentally measured formation constants constitute the simplest speciation model, which includes very few species: monomer, heptamolybdate and octamolybdate only.…”

Section: Introductionmentioning

confidence: 99%

Nucleation mechanisms and speciation of metal oxide clusters

Petrus

Segado

2020

Chem. Sci.

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Modeling the acid-base properties of molybdate(VI) in different ionic media, ionic strengths and temperatures, by EDH, SIT and Pitzer equations

Cited by 20 publications

References 41 publications

Understanding the Solution Behavior of Epinephrine in the Presence of Toxic Cations: A Thermodynamic Investigation in Different Experimental Conditions

Understanding the Solution Behavior of Epinephrine in the Presence of Toxic Cations: A Thermodynamic Investigation in Different Experimental Conditions

8-Hydroxyquinoline-2-Carboxylic Acid as Possible Molybdophore: A Multi-Technique Approach to Define Its Chemical Speciation, Coordination and Sequestering Ability in Aqueous Solution

Nucleation mechanisms and speciation of metal oxide clusters

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