The Structure of Zinc Chloride Complexes in Aqueous Solution

Maeda, Masunobu; Ito, T.; Hori, Masahito; Johansson, gGeorg

doi:10.1515/zna-1996-1-210

Cited by 45 publications

(44 citation statements)

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“…Although, the energetics of the system is functional dependent, the structural properties of a given species, are almost identical. Bond lengths between the element of interest and its neighbours is an important crystal-chemical parameter controlling isotopic properties (Schauble, 2011;Kowalski & Jahn, 2011;Kowalski et al, 2013;Méheut & Schauble, 2014) Kuzmin et al, 1997;Maeda et al, 1996). This effect is due to the GGA-PBE and vdW-DF2 exchange-correlation functionals which are known to overestimate bond lengths (e.g.…”

Section: Molecular Dynamics Modelsmentioning

confidence: 99%

Equilibrium isotopic fractionation between aqueous Zn and minerals from first-principles calculations

2018

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Theoretical mineral-solution equilibrium isotopic fractionation can contribute to the interpretation of Zn isotopic compositions. In this study, we investigate equilibrium isotopic fractionation properties of hexaaquo zinc complex, a major Zn aqueous species, using first-principles molecular dynamics (FPMD) based on density functional theory (DFT). Pentaaquo and tetraaquo zinc complexes, which can be relevant for specific mechanisms such as adsorption on mineral surfaces, are also considered. This approach takes into account both configurational and solvation effects that are less easily accounted for in molecular cluster models. The logarithmic value of the reduced partition function ratio of aqueous Zn (ln β 66 Zn/ 64 Zn) is 2.86 ± 0.04 at 295 K, while the same computational approach gave ln β 66 Zn/ 64 Zn in the range 2.2 − 4.1 for various Znbearing minerals. For example, calculations predict at 295 K, equilibrium fractionations between mineral and aqueous Zn of-0.46 for primary zinc sulfide sphalerite and of-0.20 and +0.34 for secondary phases gunningite and hydrozincite, respectively. Molecular clusters are also modelled, predicting isotopically heavier Zn with respect to related FPMD models (ln β increases by 0.09 to 0.23). These values are small but significant in the Zn isotopic system and supports the idea that a proper description of the dynamics of the system and the solvation effect are required for a reliable prediction of the isotopic properties of solvated ions.

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Section: Molecular Dynamics Modelsmentioning

confidence: 99%

Equilibrium isotopic fractionation between aqueous Zn and minerals from first-principles calculations

2018

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“…These results were confirmed using Raman, x-ray, and neutron diffraction experiments. [45][46][47] At lower concentrations octahedral species are formed mainly with water molecules. With regard to the complex formation between Zn 2+ and Cl − , thermodynamic studies in a variety of non-aqueous solutions have been reported showing that Zn 2+ forms mono-, di-, tri-, and tetra-chloro complexes depending on the chloride activity.…”

Section: Introductionmentioning

confidence: 99%

Structural characterization of zinc(II) chloride in aqueous solution and in the protic ionic liquid ethyl ammonium nitrate by x-ray absorption spectroscopy

D’Angelo

Zitolo

Ceccacci

et al. 2011

The Journal of Chemical Physics

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Extended x-ray absorption fine structure (EXAFS) spectroscopy has been used to investigate the species and structures existing in a series of ZnCl(2)-H(2)O-NaCl solutions with different chloride/zinc ratios and in a solution of ZnCl(2) in the protic ionic liquid ethyl ammonium nitrate (EAN). The average coordination numbers and distances of zinc species were determined from the analysis of the EXAFS data. In aqueous solution the number of chloride ions tightly bounded to Zn(2+) is significantly related to the chloride/zinc ratio, and no inner complex formation between Zn(2+) and Cl(-) ions has been detected for low ZnCl(2) concentration (0.1 and 0.2 M). Conversely, in the same concentration range (0.13 M) the ZnCl(2) species do not dissociate in EAN and the Zn(2+) first coordination shell has two chloride ions and is completed by two oxygen atoms of the nitrate anion. The results of this investigation show that notwithstanding the existence of similar characteristics between EAN and water, the solvation properties of the two solvents are markedly different.

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“…-. [32] The charged zinc species are not directly extractable into the ether phase, but as a neutral species, ZnCl 2 is expected to be solvated by i Pr 2 O. The examination of ZnCl 2 sigma profile reveals that a substantial part of its negatively charged sigma surface is outside of the main i Pr 2 O solvation (Figure 7, peak I).…”

Section: +mentioning

confidence: 99%

“…[24] A broader question of Ga vs. Zn selectivity arises in the context of LLE of the two metals following cyclotron production of *Ga where the concentrations of HCl and zinc may vary during irradiation due to high temperatures and radiolysis. The speciation of Ga and Zn under different HCl concentrations was studied in detail using titration, [23,31] X-ray scattering, Raman, [32] and EXAFS spectroscopy. [28] These studies provide an opportunity to inform theory about the Ga and Zn species most likely to be present in solution, which coupled with an appropriate computational technique can pave the way to a predictive quantitative model.…”

Section: Cosmo-rs Model For Extraction Of Ga and Znmentioning

confidence: 99%

Separation of Radiogallium from Zinc Using Membrane-Based Liquid-Liquid Extraction in Flow: Experimental and COSMO-RS Studies

Pedersen

Nielsen

Fonslet

et al. 2019

Solvent Extraction and Ion Exchange

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A switch from batch to continuous manufacturing of gallium-68 (68 Ga) and 68 Ga-labeled pharmaceuticals can be advantageous, as it recycles isotopically-enriched zinc-68 (68 Zn), removes pre-and post-irradiation target manipulations, and provides scalability via dose-on-demand production. Herein we report efficient extraction of radiogallium (66,67,68 Ga = *Ga) from ZnCl 2 /HCl solutions in batch and in flow using a membrane-based liquidliquid separator. From 5.6 M ZnCl 2 /3 M HCl, a 1/2 (v/v) diisopropyl ether (i Pr 2 O)/trifluorotoluene (TFT) solvent extracts 76.3 ± 1.9% of *Ga and 1.9 ± 1.6% of Zn in flow using a single pass through. From 1 M ZnCl 2 /6 M HCl, a 1/2 (v/v) n-butyl methyl ether (n-BuOMe)/TFT solvent extracts 95.7 ± 2.0% of *Ga and 0.005 ± 0.003% of Zn in flow. TFT plays a key role in controlling the interfacial tension between the aqueous and the organic phases, ensuring clean membrane-based separation. The process did not extract Cu, Mn, and Co but did extract Fe. Using HGaCl 4 and ZnCl 2 as the extractable species, the COSMO-RS theory predicts the solvation-driven extraction of Ga and Zn with a mean unsigned error of prediction of 4.0% and 3.4% respectively. KEYWORDS Gallium-68; gallium-67; liquid-liquid extraction in flow; COSMO-RS 68 Ge/ 68 Ga-generators further contribute to 68 Ga popularity in clinical and pre-clinical settings. [6] Meeting the growing demand for 68 Ga is a challenge, as it is mostly supplied by the gallium generators which suffer from high prices, long lead time, quality inconsistencies, and limited shelf life. [7] An alternative method of 68 Ga production is the irradiation of 68 Zn using a cyclotron. [8] Since many PET-centers have their own cyclotrons, this is potentially a convenient means of in-house production of 68 Ga-tracers. However, the cyclotron production of 68 Ga in solid targets from 68 Zn

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The Structure of Zinc Chloride Complexes in Aqueous Solution

Cited by 45 publications

References 0 publications

Equilibrium isotopic fractionation between aqueous Zn and minerals from first-principles calculations

Equilibrium isotopic fractionation between aqueous Zn and minerals from first-principles calculations

Structural characterization of zinc(II) chloride in aqueous solution and in the protic ionic liquid ethyl ammonium nitrate by x-ray absorption spectroscopy

Separation of Radiogallium from Zinc Using Membrane-Based Liquid-Liquid Extraction in Flow: Experimental and COSMO-RS Studies

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