ATR-FTIR spectroscopy as a probe for metal ion binding onto immobilized ligands

Alexandratos, Spiro D.; Zhu, Xiaoping

doi:10.1016/j.matchemphys.2018.07.026

Cited by 8 publications

(3 citation statements)

References 54 publications

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“…The effect of the binding mode on carboxylate stretching frequencies is well known in the literature . Phosphinic acid ligands have not been as widely studied, but previous studies have shown shifts to the symmetric and asymmetric O–P–O stretching bands of phosphinic acid ligands from aqueous positions when adsorbed to goethite , and when coordinated with metal ions in solution. , …”

Section: Resultsmentioning

confidence: 99%

“…63,64 Phosphinic acid ligands have not been as widely studied, but previous studies have shown shifts to the symmetric and asymmetric O-P-O stretch bands of phosphinic acid ligands from aqueous positions when adsorbed to goethite 65,66 and when coordinated with metal ions in solution. 67,68 Figure 10 compares the spectra of 13b adsorbed to bastnäsite in situ with the aqueous spectrum. The corresponding spectra for 10b and 24 are shown in Figures S17 and S18.…”

Section: Atr-ftir Spectra Of Ligands Adsorbed To Bastnäsitementioning

confidence: 99%

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Molecular Recognition at Mineral Interfaces: Implications for the Beneficiation of Rare Earth Ores

Sutton

Roy

Chowdhury

et al. 2020

ACS Appl. Mater. Interfaces

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Ce-bastnäsite is the single largest mineral source for light rare-earth elements. In view of the growing industrial importance of rare-earth minerals, it is critical to develop more efficient methods for separating the valuable rare-earth-containing minerals from the surrounding gangue. In this work, we employ a combination of periodic density functional theory (DFT) and molecular mechanics (MM) calculations together with the de novo molecular design program HostDesigner to identify bis-phosphinate ligands that preferentially bind to the (100) Ce-bastnäsite surface rather than the (104) calcite surface. DFT calculations for a simple phosphinate ligand were employed to qualitatively understand key behaviors involved in ligand-metal, ligand-solvent, and solvent-metal interactions. These insights were then used to guide the search for flexible, rigid, and semirigid hydrocarbon linkers to identify candidate bisphosphinate ligands with the potential to bind preferentially to Ce-bastnäsite. Among the five most promising bis-phosphinate ligands suggested by theoretical studies, three ligands were synthesized and their adsorption characteristics to bastnäsite (100) interfaces were characterized using vibrational sumfrequency (vSFG) spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and isothermal titration calorimetry (ITC). The efficacy of the selective interfacial molecular binding was demonstrated by identifying a bis-phosphinate ligand capable of providing an overall higher surface coverage of alkyl groups relative to a monophosphinate ligand. The results highlight the interplay between adsorption binding strength and maximum surface coverage in determining ligand efficiency to render the mineral surface hydrophobic. DFT calculations further indicate that all tested ligands have higher affinity for Ce-bastnäsite than for calcite. This is consistent with the ITC data showing stronger adsorption enthalpy to bastnäsite than to calcite, making these ligands promising candidates for selective flotation of Ce-bastnäsite.

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Section: Resultsmentioning

confidence: 99%

Section: Atr-ftir Spectra Of Ligands Adsorbed To Bastnäsitementioning

confidence: 99%

Molecular Recognition at Mineral Interfaces: Implications for the Beneficiation of Rare Earth Ores

Sutton

Roy

Chowdhury

et al. 2020

ACS Appl. Mater. Interfaces

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“…For the Diphonix resin and Diphonix-Ni(II) the bands are quite similar being located at 993 and 994 cm −1 . However, for Diphonix-La(III) it is located at 998 cm −1 (Alexandratos and Zhu 2018;Chiarizia et al 1995).…”

Section: Ftir Studiesmentioning

confidence: 96%

Recovery of metals from waste nickel-metal hydride batteries using multifunctional Diphonix resin

2019

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In this study, Diphonix resin containing sulfonic, diphosphonic and carboxylic groups was used to evaluate the adsorption capacity of metal ions contained in the nickel-metal hydride batteries (Ni-MH). This type of ion exchanger can be considered as the multifunctional material having great affinity to many metal ions. Using Diphonix resin adsorption process was carried out for La(III) and Ni(II) ions to characterize kinetic, adsorption and thermodynamic parameters. Preliminary studies of the Nd(III), Ce(III), La(III), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) metal ions mixture were also performed. The best results of adsorption studies were obtained using 0.2 M HNO 3. Diphonix resin exhibits especially good adsorptive properties with respect to rare earth element ions (adsorption efficiency of about 100%) in comparison with the heavy metal ions in the second oxidation state (about 50% or below). The series of affinity of the resin for the studied ions can be presented as follows: La(III) > Fe(III) > Nd(III) > Ce(III) > Cu(II) > Zn(II) > Co(II) > Ni(II). The obtained results confirmed the possibility of further use of the resin for the recovery and separation of rare earth elements from solutions after Ni-MH batteries leaching.

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