Hydrous Lanthanum Hydroxide as an Emulsifying Agent.

Moeller, Therald

doi:10.1021/j150398a011

Cited by 5 publications

(2 citation statements)

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“…Lanthanides and their compounds are of interest due to their use in catalysis, in organic synthesis, as electroluminescents, as molecular magnets, and as corrosion inhibitors . Lanthanide hydroxides [Ln(OH) 3 ] are used for defluoridation, in batteries, , for photoluminescence, , as supercapacitors, − as absorbents, , for photoelectrochemical water splitting, as emulsifying agents, and as a precursor to lanthanide oxides . Electroprecipitation has proven to be a powerful tool to fabricate Ln(OH) 3 nanostructures such as (La, Nd) nanowires, (La) nanotubes, nanospindles, nanorods, − nanocapsules, and (La, Gd) nanoparticles .…”

Section: Introductionmentioning

confidence: 99%

Electroprecipitation of Nanometer-Thick Films of Ln(OH)₃ [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

2022

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We report investigations of the deposition of nanometer-thick Ln(OH) 3 films (Ln = La, Ce, and Lu) and their effect on outer-sphere and inner-sphere electron-transfer reactions. Insoluble Ln(OH) 3 films are deposited from aqueous solutions of LaCl 3 onto the surface of 12.5 μm radius Pt microdisk electrodes during water or oxygen reduction. Both reactions produce interfacial OH − , which complexes with Ln 3+ , resulting in the precipitation of Ln(OH) 3 . Surface analyses by scanning electron microscopy (SEM), SEM−energy-dispersive X-ray spectroscopy, and atomic force microscopy indicate the formation of a 1−2 nm thick uniform film. Outer-sphere electron-transfer reactions (Ru-(NH 3 ) 6 3+ reduction, FcMeOH oxidation, and Fe(CN) 6 4−/3− oxidation/reduction) were investigated at Ln(OH) 3 -modified electrodes of different film thicknesses. The results demonstrate that the steady-state transport-limited current for these reactions decreases with an increase in the film thickness. Moreover, the degree of blockage depends upon the redox species, suggesting that the Ln(OH) 3 films are free from pinholes greater than the size of the redox molecules. This suggests that the films are either ionically conducting or that electron tunneling occurs across these thin layers. A similar blocking effect was observed for the inner-sphere reductions of H 2 O and O 2 . We further demonstrate that the thickness of La(OH) 3 films can be controlled by anodic dissolution. Additionally, we show that La 3+ lowers the supersaturation of dissolved H 2 required to nucleate a stable nanobubble.

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Section: Introductionmentioning

confidence: 99%

Electroprecipitation of Nanometer-Thick Films of Ln(OH)₃ [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

2022

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“…At the end of titra tion, opalescence was observed due to to the formation of Ln(OH) 3 colloid solutions. No dense Ln(OH) 3 pre cipitates were formed becuase of a low lanthanum(III) concentration in solution (10 -3 mol/L), intense stir ring, and the propensity of Ln(OH) 3 to form gel like system [40].…”

Section: Resultsmentioning

confidence: 99%

Hydrolysis constants of tervalent lanthanum and lanthanide ions in 0.1 M KNO3 solution

Yakubovich

Алексеев

2012

Russ. J. Inorg. Chem.

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In recent years, the growing interest is observed in studying lanthanide complexes with bioligands, such as anions of amino acids and peptides [1], tetracycline [2], quinolone [3], and β lactam [4] antibiotics, and other bioactive and medicinal substances. On the one hand, this is caused by the creation of new high sensi tive methods for the analysis of bioobjects on the basis of the luminescent properties of lanthanide complexes [5] and, on the other hand, by the prospects of the application of these complexes as medicines [6][7][8]. Moreover, studies of lanthanide ion complexes give interesting information on the coordination abilities of bioligands. As a rule, lanthanide complexes with bioligands are formed in a neutral or weakly alkaline medium, thus requiring the hydrolysis of Ln 3+ ions to be correctly taken into consideration and the hydroly sis constants K h determined under the same experi mental conditions to be introduced into computa tional equations.The hydrolysis of Ln 3+ ions have been studied repeatedly. A review of the works published on this topic before 1977 is given in [9]. Later obtained results are reviewed in . However, K h values estimated in most of these works can usually not be used to study complexation processes, as they were determined under other conditions (at a very high or low ionic strength and a temperature different from 25°С). In many cases, data were obtained for only some ions instead of the entire series of lanthanides. The thermo dynamic hydrolysis constants obtained in some works via referring values to zero ionic strength have different values (Table 1).Having the further study of complexation of lan thanide(III) ions with a number of bioligands in the view, in this work we were intended to estimate the hydrolysis constants of Ln 3+ ions at 25°С by pH titra tion against the background of 0.1 M KNO 3 , that is, under the conditions typical for studying complex ation in solutions. EXPERIMENTAL 0.05 M Ln(NO 3 ) 3 solutions (where Ln is La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu) were prepared from weighed portions of recrystallized Ln(NO 3 ) 3 ⋅ 6H 2 O salts and standardized by complexo metric titration. The purity of Ln(NO 3 ) 3 ⋅ 6H 2 O sam ples was monitored by X ray fluorescence spectros copy on a Spectroscan Max G. spectrometer. A 0.1 M KNO 3 solution was prepared from a weighed portion of KNO 3 (chemically pure grade). A 0.0429 M NaOH solution was prepared from a weighed portion of metallic sodium and standardized by the pH titration of a weighed portion of potassium biphthalate. All solutions were prepared with the use of bidistilled water previously boiled to remove CO 2 . pH was mea sured on a Microtechna M120 ion meter equipped with a Crytur 01 21 measuring glass electrode and a Radelkis OP 0830P saturated calomel reference elec trode. The system was calibrated against buffer solu tions of Na 2 B 4 O 7 (pH 9.18 at 25°С) and KH 3 (C 2 O 4 ) 2 (pH 1.68 at 25°С). The pH measurement accuracy was ±0.01.A 0.1 M KNO 3 solution (100 mL) and a Ln(NO 3 ) 3 s...

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Insoluble Solids as Emulsifiers**School of Pharmacy, University of North Carolina, Chapel Hill

Jowdy¹,

Brecht²

1957

Journal of the American Pharmaceutical Association (Scientific

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Hydrous Lanthanum Hydroxide as an Emulsifying Agent.

Cited by 5 publications

References 5 publications

Electroprecipitation of Nanometer-Thick Films of Ln(OH)₃ [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

Electroprecipitation of Nanometer-Thick Films of Ln(OH)₃ [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

Hydrolysis constants of tervalent lanthanum and lanthanide ions in 0.1 M KNO3 solution

Insoluble Solids as Emulsifiers**School of Pharmacy, University of North Carolina, Chapel Hill

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Hydrous Lanthanum Hydroxide as an Emulsifying Agent.

Cited by 5 publications

References 5 publications

Electroprecipitation of Nanometer-Thick Films of Ln(OH)3 [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

Electroprecipitation of Nanometer-Thick Films of Ln(OH)3 [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

Hydrolysis constants of tervalent lanthanum and lanthanide ions in 0.1 M KNO3 solution

Insoluble Solids as Emulsifiers**School of Pharmacy, University of North Carolina, Chapel Hill

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Electroprecipitation of Nanometer-Thick Films of Ln(OH)₃ [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions

Electroprecipitation of Nanometer-Thick Films of Ln(OH)₃ [Ln = La, Ce, and Lu] at Pt Microelectrodes and Their Effect on Electron-Transfer Reactions