Speciation of Al3+ in fairly concentrated solutions (20 to 200 mmol L-1) at I = 1 mol L-1 (NaNO3), in the acidic pH range, at different temperatures.

AbstractThe hydrolysis of Al3+ was studied in aqueous 1 mol L−1 NaNO3 solution at different concentrations (20–200 mmol L−1) and temperatures (283.15–343.15 K) by potentiometry (ISE-H+, glass electrode). Many different speciation models were considered in the calculations and it was found that the best model is represented by the following species: Al(OH)2+, Al(OH)45+, Al13(OH)327+. Hydrolysis constants and enthalpy changes at different temperatures are reported.

The solution behavior of dopamine in the presence of mono and divalent cations: A thermodynamic investigation in different experimental conditions

The interactions of dopamine [2-(3,4-Dihydroxyphenyl)ethylamine, (Dop-)] with methylmercury(II) (CH3Hg+), magnesium(II), calcium(II), and tin(II) were studied in NaCl(aq) at different ionic strengths and temperatures. Different speciation models were obtained, mainly characterized by mononuclear species. Only for Sn2+ we observed the formation of binuclear complexes (M2L2 and M2LOH (charge omitted for simplicity)

Hydrolysis of organotin compounds at high concentration

Speciation Studies of Bifunctional 3-Hydroxy-4-Pyridinone Ligands in the Presence of Zn2+ at Different Ionic Strengths and Temperatures

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Speciazione di Sn(II) in presenza di leganti O-donatori di interesse biologico

Lo stagno è il ventiquattresimo elemento più abbondante nella crosta terrestre ed ha il più elevato numero di isotopi stabili (dieci). Generalmente questo elemento non viene annoverato tra gli inquinanti più importanti, in quanto lo stagno inorganico non risulta particolarmente tossico. Tuttavia, molti dei suoi sali lo sono. Infatti, la corrosione di contenitori in stagno da parte di cibi e bevande acide ha causato in passato numerosi intossicazioni ad opera di composti solubili di questo metallo. Inoltre, la bioalchilazione dello stagno inorganico porta alla formazione di composti ancor più nocivi per l’ambiente. Per tali ragioni, per esempio, la Food Standards Agency del Regno Unito ha im…

The Effect of Metal Cations on the Aqueous Behavior of Dopamine. Thermodynamic Investigation of the Binary and Ternary Interactions with Cd2+, Cu2+ and UO22+ in NaCl at Different Ionic Strengths and Temperatures

The interactions of dopamine [2-(3,4-Dihydroxyphenyl)ethylamine, (Dop−)] with cadmium(II), copper(II) and uranyl(VI) were studied in NaCl(aq) at different ionic strengths (0 ≤ I/mol dm−3 ≤ 1.0) and temperatures (288.15 ≤ T/K ≤ 318.15). From the elaboration of the experimental data, it was found that the speciation models are featured by species of different stoichiometry and stability. In particular for cadmium, the formation of only MLH, ML and ML2 (M = Cd2+; L = dopamine) species was obtained. For uranyl(VI) (UO22+), the speciation scheme is influenced by the use of UO2(acetate)2 salt as a chemical; in this case, the formation of ML2, MLOH and the ternary MLAc (Ac = acetate) species in a …

Hydrolysis of Monomethyl-, Dimethyl-, and Trimethyltin(IV) Cations in Fairly Concentrated Aqueous Solutions at I = 1 mol L-1 (NaNO3) and T = 298.15 K. Evidence for the Predominance of Polynuclear Species

The hydrolysis of methyltin(IV) cations at fairly high concentrations was investigated to evaluate the formation of polynuclear species in aqueous solution. The hydrolysis of monomethyltin(IV), dimethyltin(IV), and trimethyltin(IV) was studied by potentiometry at T = 298.15 K and at I = 1 mol L-1 in NaNO3 aqueous solutions. The results obtained gave evidence for the formation of the following polynuclear species, in addition to the mononuclear species already reported, which were also considered in the models proposed for the three systems investigated: [(CH3)Sn(OH)3]0, [(CH3)Sn(OH)4]-, [((CH3)Sn)2(OH)4]2+, [((CH3)Sn)2(OH)5]+, [((CH3)Sn)2(OH)7]-, [((CH3)Sn)3(OH)5]4+, [((CH3)Sn)3(OH)7]2þ, [(…

Polycarboxylic acids in sea water: acid–base properties, solubilities, activity coefficients, and complex formation constants at different salinities

This paper reports the results of the investigations carried out in synthetic sea water at different salinities for different classes of polycarboxylic acids. The investigations can be summarized as follows: (a) Determination of the protonation constants in such multicomponent solution in a salinity range 15 ≤ S ≤ 45, at t = 25 °C, for the linear dicarboxylic acids HOOC-(CH2) n –COOH (0 ≤ n ≤ 8), and aromatic polycarboxylic acids (o-phthalic and 1,2,4-benzenetricarboxylic acids). For malonic, succinic, 1,2,3-benzenetricarboxylic, and 1,2,3,4-benzenetetracarboxylic acids, investigations were also carried out at t = 10 and 37 °C; (b) Determination of the total and intrinsic solubility (S T an…

Speciation of tin(II) in aqueous solution: thermodynamic and spectroscopic study of simple and mixed hydroxocarboxylate complexes

This contribution reports the results of potentiometric and Mossbauer investigations on the formation, stability, and structure of binary and ternary mono- and binuclear complexes of Sn2+ with three hydroxocarboxylic ligands (namely L = tartrate, malate, and citrate) and chloride at T = 298.15 K in different ionic media and ionic strengths (0.15 and 1.00 mol dm−3 in NaCl(aq) and 1.00 mol dm−3 in NaNO3(aq)). The stability constants of various simple Sn i H j L (2+−) and mixed Sn i H j L k Cl (2+−−) species obtained in the different experimental conditions are reported, and various speciation diagrams of the simple and mixed systems are shown in different conditions. The sequestering ability …

Enhancement of Hydrolysis through the Formation of Mixed Heterometal Species: Al3+/CH3Sn3+ Mixtures

ABSTRACT: The hydrolysis of mixed-metal cations (Al3+/CH3Sn3+) was studied in aqueous solutions of NaNO3, at I = 1.00 ± 0.05 mol·dm−3 and T = 298.15 K, by potentiometric technique. Several hydrolytic mixed species are formed in this mixed system, namely, Alp(CH3Sn)q(OH)r with (p, q, r) = (1, 1, 4), (1, 1, 5), (1, 1, 6), (2, 1, 4), (1, 2, 5), (1, 4, 11), (1, 3, 8), and (7, 6, 32). The stability of these species, expressed by the equilibrium: pAl3+ + qCH3Sn3+ + rOH− = Alp(CH3Sn)q(OH)r 3(p+q)−r, βpqr OH, can be modeled by the empirical relationship: log βpqr OH = −3.34 + 2.67p + 9.23(q + r). By using the equilibrium constant Xpqr relative to the formation reaction: pAl(p+q)(OH)r + q(CH3Sn)(p+q…