Extraction of cadmium by TODGA–dodecane and TBP–dodecane: A comparative study by MD simulation

Singh, Meena B.; Mukhtyar, Ankita; Bootwala, Yousuf; Gaikar, Vilas G.

doi:10.1080/01496395.2017.1282967

Cited by 5 publications

(3 citation statements)

References 32 publications

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“…To assist the development of LLExt protocols, in an earlier work, MD simulations have been carried out to study the biphasic behavior of extractants and the extracted complexes. For example, these studies covered the ligands of BTPhen, BTBP, 18-Crown-6, − tri- n -butyl phosphate (TBP), − calix[4]arene, N , N -di(2-ethylhexyl)isobutyramide (DEHiBA), and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEHEHP) . It is now established that the complexation of ligands with metal ions happened at the interface.…”

Section: Discussionmentioning

confidence: 99%

Key Factors Determining Efficiency of Liquid–Liquid Extraction: Implications from Molecular Dynamics Simulations of Biphasic Behaviors of CyMe₄-BTPhen and Its Am(III) Complexes

et al. 2020

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zotriazin-3-yl)-1,10-phenanthroline, denoted as L) has been considered as a promising extractant in lanthanide(III)/actinide(III) separation. Vast endeavors in its application put forward a compelling need on the understanding of the underlying mechanism in the liquid−liquid extraction. To address the issue of its dynamics in biphasic systems, we carried out molecular dynamics (MD) simulations of L and its complexes with a heavy f-block metal ion, americium(III) (Am 3+ ) in "oil"/water binary solvents. Two types of organic phases have been considered, differing in the presence of octanol in the bulk ndodecane or not, and the distribution of the solutes and their interfacial behaviors have been investigated. Two of the key factors that determine the efficiency of a liquid−liquid extraction protocol were delineated and discussed, that is, the appropriate ligand to enhance the lipophilicity of AmL complexes and appropriate way to form ion pairs to minimize the attraction between the complexes and aqueous phase. The simulations showed that the charge states of both ligand and AmL complexes were strongly correlated with their phase behavior, and the migration of neutral species was driven by van der Waals interactions while that of charged species by electrostatic interactions, indicating stronger lipophilicity of the former than the latter. The presence of octanol facilitated the migration of the ligand from the interface to the organic phase via hydrogen bond between its polar head and the ligand or the AmL complexes and constituted a polar core in the organic phase. This work bridged the widely used liquid−liquid extraction technique in chemistry to a fundamental chemical concept, that is, minimization of hydrophilicity and maximization of lipophilicity to facilitate phase transfer from the aqueous phase to the organic phase, and is expected to improve the understanding of dynamics of ligands and their complexes with metal ions and to contribute to the development of efficient protocols for phase transfer of target species.

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Section: Discussionmentioning

confidence: 99%

Key Factors Determining Efficiency of Liquid–Liquid Extraction: Implications from Molecular Dynamics Simulations of Biphasic Behaviors of CyMe₄-BTPhen and Its Am(III) Complexes

et al. 2020

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“…It was known that the nonhydrated Cd(II) adsorption energy on the SiO 2 surface was −2.96 eV. However, the [Cd (H 2 O) 6 ] 2+ (the hydrated Cd(II) existed as the form of hexacoordination with H 2 O) 50 adsorption energy on the SiO 2 surface was 0.692 eV. Moreover, 0.0710 e − electrons were transferred in the [Cd (H 2 O) 6 ] 2+ adsorption, and this value was obviously smaller than that in the Cd(II) adsorption (0.865 e − ), indicating that the hydrated layer hindered the charge transfer in the Cd(II) adsorption process.…”

Section: Effect Of Degree Of Silicification On Cd(ii) Boundmentioning

confidence: 99%

Effect of Degree of Silicification on Silica/Silicic Acid Binding Cd(II) and Its Mechanism

Zheng

Chen

et al. 2019

J. Phys. Chem. A

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Heavy metal pollution in farmland soil reduces crop yield and quality and also potentially causes the crisis to human health. Formerly, the fact that silicon fertilizer could effectively reduce the residual concentration of heavy metal in crops has been identified at the tissue level. In this paper, molecular dynamics simulation was employed to investigate the effects of the degree of silicification of silicic acids [namely, the molar ratio of Si(OH) 4 and SiO 2 ] on the Cd(II) bound in the aspect of radial distribution functions and mean square displacements. The results demonstrated that Si(OH) 4 attracted Cd(II) through the coordination, while SiO 2 attracted Cd(II) by the adsorption. In particular, when the degree of silicification was 0, both the bound Cd(II) amount and strength were the maximum value, indicating that the silicon fertilizer had the best efficiency of Cd(II) bound as Si(OH) 4 . By comparing the adsorption energy and electronic transfer of Cd(II) and Si(OH) 4 adsorption onto the SiO 2 surface through the quantum chemical simulation, we concluded that Cd(II) adsorption onto the SiO 2 surface was chemisorption, while the Si(OH) 4 adsorption onto SiO 2 surface was physisorption. Consequently, the adsorption capacity of Cd(II) on the SiO 2 surface was higher than that of Si(OH) 4 adsorption on the SiO 2 surface. Moreover, the compact hydration layers around Cd(II) prevented the process of Cd(II) adsorption on the SiO 2 surface; even so, the counterion Cl − in the system promoted the adsorption process. The mechanism of silicon fertilizer binding heavy metal Cd(II) was investigated and revealed at the molecular and electronic level. This work has expanded the possibility of theoretical guidance for the design of silicon fertilizer.

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“…MD simulations have proven useful for providing understanding of TODGA solvent complexation, extraction, and selectivity in a variety of diluents and extraction systems. [38][39][40][41][42][43][44][45][46] By modeling TODGA in the above four solvents, while keeping in mind the framework described in Fig. 1, ligand self-association and the resultant effects on energetics and liquid structures can be not only described, but also meaningfully quantified.…”

Section: Introductionmentioning

confidence: 99%

Molecular-scale understanding of diluent effects on ligand assembly for metal ion separations

Poe,

Seifert,

Servis

2024

Phys. Chem. Chem. Phys.

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Extraction of cadmium by TODGA–dodecane and TBP–dodecane: A comparative study by MD simulation

Cited by 5 publications

References 32 publications

Key Factors Determining Efficiency of Liquid–Liquid Extraction: Implications from Molecular Dynamics Simulations of Biphasic Behaviors of CyMe₄-BTPhen and Its Am(III) Complexes

Key Factors Determining Efficiency of Liquid–Liquid Extraction: Implications from Molecular Dynamics Simulations of Biphasic Behaviors of CyMe₄-BTPhen and Its Am(III) Complexes

Effect of Degree of Silicification on Silica/Silicic Acid Binding Cd(II) and Its Mechanism

Molecular-scale understanding of diluent effects on ligand assembly for metal ion separations

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Extraction of cadmium by TODGA–dodecane and TBP–dodecane: A comparative study by MD simulation

Cited by 5 publications

References 32 publications

Key Factors Determining Efficiency of Liquid–Liquid Extraction: Implications from Molecular Dynamics Simulations of Biphasic Behaviors of CyMe4-BTPhen and Its Am(III) Complexes

Key Factors Determining Efficiency of Liquid–Liquid Extraction: Implications from Molecular Dynamics Simulations of Biphasic Behaviors of CyMe4-BTPhen and Its Am(III) Complexes

Effect of Degree of Silicification on Silica/Silicic Acid Binding Cd(II) and Its Mechanism

Molecular-scale understanding of diluent effects on ligand assembly for metal ion separations

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Product

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Key Factors Determining Efficiency of Liquid–Liquid Extraction: Implications from Molecular Dynamics Simulations of Biphasic Behaviors of CyMe₄-BTPhen and Its Am(III) Complexes

Key Factors Determining Efficiency of Liquid–Liquid Extraction: Implications from Molecular Dynamics Simulations of Biphasic Behaviors of CyMe₄-BTPhen and Its Am(III) Complexes