%Calorimetric Determinations of Ba<sup>2+</sup> and La<sup>3+</sup> in the Ion-Exchange Process Involving Pure and Modified α-Titanium Phosphates

Airoldi, Cláudio; Nunes, Liliane M.

doi:10.1021/la9902892

Cited by 14 publications

(4 citation statements)

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“…The most important layered titanium phosphates are the α- and γ-phases. The α-Ti(HPO 4 ) 2 ·H 2 O (denoted α-TiP) was first synthesized in 1967 by Alberti et al The ion-exchange and intercalation behaviors of α-TiP have been widely studied, including ion exchange toward alkali, alkaline earth, and transition-metal ions and intercalations of various amines, such as alkyl amines, aromatic amines, and heterocyclic amines . The γ-Ti(PO 4 )(H 2 PO 4 )·2H 2 O (denoted γ-TiP) was synthesized shortly after the discovery of α-TiP.…”

Section: Introductionmentioning

confidence: 99%

A ^47/49Ti Solid-State NMR Study of Layered Titanium Phosphates at Ultrahigh Magnetic Field

et al. 2009

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Layered titanium phosphates (TiPs) have many potentially important applications in ion exchange, catalysis, intercalation, and sorption. Characterization of metal local environments by solid-state 47/49Ti NMR has been difficult due to many unfavorable 47/49Ti NMR properties. In this work, we have directly characterized the local structures around Ti in several representative layered TiPs, including α-, β-, and γ-TiP, by examining the 47/49Ti static NMR spectra of these materials at an ultrahigh magnetic field of 21.1 T. The 47/49Ti chemical shielding and electric field gradient (EFG) tensors have been extracted from spectral analysis. The observed 47/49Ti spectra are mainly determined by the second-order quadrupolar interactions. The quadrupole coupling constants (C Q) are sensitive to the distortion of the TiO6 octahedron in this series of layered TiPs. Quantum mechanical calculations have been performed on several model clusters as well as periodic systems. The results indicate that, in addition to the oxygens in the first coordination sphere of Ti, the atoms in the second and third coordination spheres and beyond also have significant effects on the EFG at the metal center, and this long-range effect contributes substantially to the C Q. A relationship between observed C Q and the Ti−O bond length distortion parameter appears to exist, and this empirical correlation is also confirmed by theoretical calculations. Using sodium-exchanged α-TiP (α-Na-TiP) with an unknown structure as an example, we show that the 47/49Ti NMR spectra can provide partial information on the local environment of the metal center. For this material, the ion exchange does not affect the Ti local environment significantly. It appears that the layer in α-TiP is more robust compared to that of the zirconium analogue.

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Section: Introductionmentioning

confidence: 99%

A ^47/49Ti Solid-State NMR Study of Layered Titanium Phosphates at Ultrahigh Magnetic Field

et al. 2009

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“…This set of thermodynamic data associated with low endothermic values for spontaneous reactions, as expressed by negative Gibbs energy and favorable from the entropic point of view, reflect weaker interactive processes, as represented by ionic exchange, as observed for other systems [35,36].…”

Section: Tablementioning

confidence: 59%

Isomorphic silicon/aluminum substitution on layered ilerite – Structural study and calorimetry of copper interaction

Pires¹,

Costa²,

Airoldi³

2012

Microporous and Mesoporous Materials

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“…This synthetic crystalline compound was prepared according to Airoldi and Nunes (2000). For the conditioning of TiP with n-butylamine (nba), 1.5 g of TiP was transferred to a dry washing bottle.…”

Section: Preparation Of Tip and Its Conditioning With N-butylaminementioning

confidence: 99%

Flow Injection Photoamperometric Investigation of Ascorbic Acid Using Methylene Blue Immobilized on Titanium Phosphate

Dilgin

Nisli

2006

Analytical Letters

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Methylene blue (MB) was incorporated into titanium phosphate (TiP) after pretreatment of TiP with the gas, n-butyl amine. The dye is strongly retained and not easily leached from the layered host matrix. The adsorbed MB on TiP was used to prepare modified carbon paste electrodes (MCPE), which were studied voltammetrically and in amperometric flow injection (FI) mode for the electrocatalytic oxidation of ascorbic acid (AA). The electrochemical behavior of the immobilized dye was investigated with cyclic voltammetry, at a pH 7.0 phosphate buffer containing 0.5 M KCl, at different potential scan rates. The MB immobilized on the support underwent a quasireversible electrochemical redox reaction. A homemade flow-through electrochemical cell with a suitable transparent window for irradiation of the electrode surface was constructed and used for amperometric FI studies. The photoamperometric-FI conditions were optimized for sensitivity and reproducibility at a flow rate of 1.5 mL/min, a transmission tubing length of 25 cm, a sample injection volume of 100 mL, and a constant applied potential of þ100 mV vs. SCE. The calibration curve for AA was linear over the concentration range from 1.0 Â 10 26 to 2.5 Â 10 25 mol l 21 for both amperometric and photoamperometric studies. But the slope of the photoelectrocatalytic FIA 451procedure was improved about 52% compared with those obtained without irradiation. The results obtained for AA determination in some pharmaceutical products are in good agreement with those obtained using the procedure involving the reaction between triiodide and AA.

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%Calorimetric Determinations of Ba²⁺ and La³⁺ in the Ion-Exchange Process Involving Pure and Modified α-Titanium Phosphates

Cited by 14 publications

References 27 publications

A ^47/49Ti Solid-State NMR Study of Layered Titanium Phosphates at Ultrahigh Magnetic Field

A ^47/49Ti Solid-State NMR Study of Layered Titanium Phosphates at Ultrahigh Magnetic Field

Isomorphic silicon/aluminum substitution on layered ilerite – Structural study and calorimetry of copper interaction

Flow Injection Photoamperometric Investigation of Ascorbic Acid Using Methylene Blue Immobilized on Titanium Phosphate

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%Calorimetric Determinations of Ba2+ and La3+ in the Ion-Exchange Process Involving Pure and Modified α-Titanium Phosphates

Cited by 14 publications

References 27 publications

A 47/49Ti Solid-State NMR Study of Layered Titanium Phosphates at Ultrahigh Magnetic Field

A 47/49Ti Solid-State NMR Study of Layered Titanium Phosphates at Ultrahigh Magnetic Field

Isomorphic silicon/aluminum substitution on layered ilerite – Structural study and calorimetry of copper interaction

Flow Injection Photoamperometric Investigation of Ascorbic Acid Using Methylene Blue Immobilized on Titanium Phosphate

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%Calorimetric Determinations of Ba²⁺ and La³⁺ in the Ion-Exchange Process Involving Pure and Modified α-Titanium Phosphates

A ^47/49Ti Solid-State NMR Study of Layered Titanium Phosphates at Ultrahigh Magnetic Field

A ^47/49Ti Solid-State NMR Study of Layered Titanium Phosphates at Ultrahigh Magnetic Field