La3+ and Y3+ interactions with the carboxylic acid moiety at the liquid/vapor interface: Identification of binding complexes, charge reversal, and detection limits

Sthoer, Adrien; Adams, Ellen M.; Sengupta, Sanghamitra; Corkery, Robert W.; Allen, Heather C.; Tyrode, Eric

doi:10.1016/j.jcis.2021.10.052

Cited by 27 publications

(51 citation statements)

References 77 publications

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“…The decrease in intensities can have two main reasons, both resulting from the ion adsorption to the monolayer. 56,74,75 Ion adsorption can screen the surface charge of the interfacial film thus effectively reducing the electric field normal to the liquid surface facing down into the subphase.…”

Section: Interfacial Water Structure Near Graphene Oxidementioning

confidence: 99%

Effects of Ion Adsorption on Graphene Oxide Films and Interfacial Water Structure: A Molecular-Scale Description

Carr

Kumal

et al. 2022

Preprint

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Graphene oxide is a promising, emerging separation material, as it is durable, dispersible in water, and has naturally forming functional groups. Bulk studies using graphene oxide flakes have demonstrated impressive metal adsorption. However, little interfacial information about water and metal organization near graphene oxide is available. A mechanistic understanding of water and ions interactions with graphene oxide films is critical toward advanced separations, including improved sorption efficiency and membrane regeneration. We study metal ion and local water organization near graphene oxide thin films formed at the air/water interface. These films are not typical membranes and allow us to determine nanoscale information about the graphene oxide-water interface. We accomplish this with x-ray reflectivity (XR), x-ray fluorescence near total reflection (XFNTR), and vibrational sum frequency generation spectroscopy (SFG). These interface-specific techniques provide the electron density profile normal to the interface, number of adsorbed ions, and information about the orientational ordering and hydrogen-bonding network of interfacial water, respectively. Via XFNTR and SFG, we find that trivalent yttrium ions preferentially adsorb to graphene oxide and affect its structure, compared to divalent strontium and monovalent cesium ions. Two different interfacial water populations can be described, based on their hydrogen bonding strength, and the adsorbed ions affect these populations differently. These results provide fundamental information about ion and water organization at the interface and help address the large computational-experimental agreement gap for graphene oxide systems. Additionally, they are relevant for improved soft-scaffold graphene oxide membranes and downstream applications.

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Section: Interfacial Water Structure Near Graphene Oxidementioning

confidence: 99%

Effects of Ion Adsorption on Graphene Oxide Films and Interfacial Water Structure: A Molecular-Scale Description

Carr

Kumal

et al. 2022

Preprint

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“…As the obtained surface area is significantly less than this minimum, the speciation of Lu is probably different from the trivalent species found in bulk solution, i.e., counterions may be present in the bilayer to compensate the charge. The presence of divalent hydroxyl-lanthanide species next to an anionic monolayer has been recently reported …”

Section: Resultsmentioning

confidence: 97%

Spontaneous and Ion-Specific Formation of Inverted Bilayers at Air/Aqueous Interface

2022

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Developing better separation technologies for rare earth metals, an important aspect of a sustainable materials economy, is challenging due to their chemical similarities. Identifying molecular scale interactions that amplify the subtle differences between the rare earths can be useful in developing new separation technologies. Here, we describe ion-dependent monolayer to inverted bilayer transformation of extractant molecules at the air/aqueous interface. The inverted bilayers form with Lu 3+ ions but not with Nd 3+ . By introducing Lu 3+ ions to preformed monolayers, we extract kinetic parameters corresponding to the monolayer to inverted bilayer conversion. Temperature-dependent studies show Arrhenius behavior with an energy barrier of 40 kcal/mol. The kinetics of monolayer to inverted bilayer conversion is also affected by the character of the background anion, although anions are expected to be repelled from the interface. Our results show the outsized importance of ion-specific effects on interfacial structure and kinetics, pointing to their role in chemical separation methods.

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“…All solutions were prepared in a background of 20 μM EDTA, for which the pH had been adjusted before adding the salt. The addition of EDTA is critical for avoiding trace amounts of divalent/trivalent ions from interacting with the fatty acid monolayer. , Anion specific interactions were observed at the silica surface of the pH electrode, particularly for the more polarizable anions such as SCN – and I – . Thus, the pH was systematically verified before and after experiments with different pH indicator papers (MColorpHast pH 0–14, 4.0–7.0, 6.5–10, and 11.0–13.0 and Whatman Panpeha pH 0–14 from Merck).…”

Section: Methodsmentioning

confidence: 99%

“… 31 Anion specific effects have also been reported on a negatively charged dihexadecyl phosphate monolayer, but only in the presence of trivalent cations in solution. 32 In such a case, the preferential adsorption of the trivalent cation leads to charge reversal and a net positively charged surface, 8 where anions can more readily interact. No such effect is expected for monovalent cations.…”

Section: Introductionmentioning

confidence: 99%

“…The ensuing negative surface potential creates an electrical double layer (EDL), where ions in solution redistribute to screen the surface charge. , Because of basic electrostatic arguments, counterions (i.e., cations) are enriched at the surface, while co-ions (i.e., anions) are instead expected to be largely expelled. It becomes then obvious why the vast majority of the research on specific interactions of ions with carboxylic acids monolayers has focused on the cations. − …”

Section: Introductionmentioning

confidence: 99%

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Anion Specific Effects at Negatively Charged Interfaces: Influence of Cl^–, Br^–, I^–, and SCN^– on the Interactions of Na⁺ with the Carboxylic Acid Moiety

Sthoer

Tyrode

2021

J. Phys. Chem. B

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Unlike counterion interactions with charged interfaces, the influence of co-ions is only scarcely reported in the literature. In this work, the effect of SCN − and the halide co-ions in the interactions of Na + with carboxylic acid Langmuir monolayers is investigated by using vibrational sum frequency spectroscopy. At 1 M concentrations in the subphase, the identity of the anion is shown to have a remarkable influence on the charging behavior and degree of deprotonation of the monolayer, with ions ordering in the sequence I − > SCN − > Cl − ≈ Br − . The same trend is observed at both pH 6 and pH 9 when the monolayer is intrinsically more charged. Spectroscopic evidence is found for both the presence of I − and SCN − in the interfacial region at levels close to their detection limits. The results contradict electrostatic theories on charged interfaces where co-ions are not expected to play any significant role. The higher propensity for the large polarizable anions to deprotonate the monolayer is explained in terms of their ability to modify the cations affinity toward the carboxylic acid groups present at the surface.

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La3+ and Y3+ interactions with the carboxylic acid moiety at the liquid/vapor interface: Identification of binding complexes, charge reversal, and detection limits

Cited by 27 publications

References 77 publications

Effects of Ion Adsorption on Graphene Oxide Films and Interfacial Water Structure: A Molecular-Scale Description

Effects of Ion Adsorption on Graphene Oxide Films and Interfacial Water Structure: A Molecular-Scale Description

Spontaneous and Ion-Specific Formation of Inverted Bilayers at Air/Aqueous Interface

Anion Specific Effects at Negatively Charged Interfaces: Influence of Cl^–, Br^–, I^–, and SCN^– on the Interactions of Na⁺ with the Carboxylic Acid Moiety

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La3+ and Y3+ interactions with the carboxylic acid moiety at the liquid/vapor interface: Identification of binding complexes, charge reversal, and detection limits

Cited by 27 publications

References 77 publications

Effects of Ion Adsorption on Graphene Oxide Films and Interfacial Water Structure: A Molecular-Scale Description

Effects of Ion Adsorption on Graphene Oxide Films and Interfacial Water Structure: A Molecular-Scale Description

Spontaneous and Ion-Specific Formation of Inverted Bilayers at Air/Aqueous Interface

Anion Specific Effects at Negatively Charged Interfaces: Influence of Cl–, Br–, I–, and SCN– on the Interactions of Na+ with the Carboxylic Acid Moiety

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Product

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Anion Specific Effects at Negatively Charged Interfaces: Influence of Cl^–, Br^–, I^–, and SCN^– on the Interactions of Na⁺ with the Carboxylic Acid Moiety