Mechanism of Deposition of the CrO42-, HCrO4-, and Cr2O72- Ions on the .gamma.-Alumina Surface

Spanos, N.; Slavov, S.; Kordulis, Christos; Lycourghiotis, Alexis

doi:10.1021/la00021a042

Cited by 36 publications

(56 citation statements)

References 11 publications

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“…Moreover, a value equal to 8.8 kJ mol −1 was found for the energy of the lateral interactions, E0λГ m . This value is comparable with the energy of the lateral interactions found for the adsorbed molybdate [44] and chromate [45] ions on the surface of γ-alumina.…”

Section: Methodssupporting

confidence: 83%

Adsorption monitoring of phospho-l-serine on hydroxyapatite

Skartsila

Spanos

2012

Colloid Polym Sci

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The adsorption of the aminoacid phospho-Lserine (PLS) on the surface of hydroxyapatite {Ca 5 (PO 4 ) 3 OH, HAP}, was investigated using streaming potential measurements. Solutions saturated with respect to HAP, containing different concentrations of PLS, were brought in contact under carefully controlled flow conditions through plugs made of well dispersed HAP powder. The measurement of PLS adsorption during the equilibration of the solute with the HAP substrate, showed a plateau regime corresponding, according to geometrical considerations, to monolayer surface coverage. The PLS uptake measurements on HAP suggested that it is possible to monitor in situ adsorption during the monolayer surface coverage measuring the streaming potential of HAP. Analysis of the surface potential measurements suggested that during the monolayer surface coverage step, the negatively charged (HL 2− ) PLS species were adsorbed. The adsorbed HL 2− was located at the inner Helmholtz plane of the electrical double layer, forming surface complexes with the positively charged ≡CaOH 2 + sites on the surface of HAP. The rate constants of adsorption and desorption were calculated from the kinetics of adsorption of PLS on HAP.

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Section: Methodssupporting

confidence: 83%

Adsorption monitoring of phospho-l-serine on hydroxyapatite

Skartsila

Spanos

2012

Colloid Polym Sci

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“…The decrease in interaction between the support and the active component is due to the changes in hydroxyl cover of the support. The isoelectronic point (IEP) of alumina is 7.2-8.6, and the IEP of silica is 2.0-3.9 [34][35][36]. This is caused by the predominance of the following reactions on the surface of the hydrated supports [34,36]: The decrease in interaction between the support and the active component is due to the changes in hydroxyl cover of the support.…”

Section: Active Component Of Catalystsmentioning

confidence: 99%

“…This is caused by the predominance of the following reactions on the surface of the hydrated supports [34,36]: The decrease in interaction between the support and the active component is due to the changes in hydroxyl cover of the support. The isoelectronic point (IEP) of alumina is 7.2-8.6, and the IEP of silica is 2.0-3.9 [34][35][36]. This is caused by the predominance of the following reactions on the surface of the hydrated supports [34,36]:…”

Section: Active Component Of Catalystsmentioning

confidence: 99%

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Modification by SiO2 of Alumina Support for Light Alkane Dehydrogenation Catalysts

et al. 2016

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Due to the continuously rising demand for C 3 -C 5 olefins it is important to improve the performance of catalysts for dehydrogenation of light alkanes. In this work the effect of modification by SiO 2 on the properties of the alumina support and the chromia-alumina catalyst was studied. SiO 2 was introduced by impregnation of the support with a silica sol. To characterize the supports and the catalysts the following techniques were used: low-temperature nitrogen adsorption; IR-spectroscopy; magic angle spinning 29 Si nuclear magnetic resonance; temperature programmed desorption and reduction; UV-Vis-, Raman-and electron paramagnetic resonance (EPR)-spectroscopy. It was shown that the modifier in amounts of 2.5-7.5 wt % distributed on the support surface in the form of SiO x -islands diminishes the interaction between the alumina support and the chromate ions (precursor of the active component). As a result, polychromates are the compounds predominantly stabilized on the surface of the modified support; under thermal activation of the catalyst and are reduced to the amorphous Cr 2 O 3 . This in turn leads to an increase in the activity of the catalyst in the dehydrogenation of isobutane.

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“…The selection of an inorganic solid for removing polluting agents is based on its structural, superficial characteristics and selectivity, besides its stability to chemical processes, radiation and temperature. [4][5][6] Metal phosphates possessing remarkably large internal surface areas and narrow pore size distributions have attracted considerable attention for their great potential application as catalysts, adsorbents, and host materials. Recently, much work has been devoted to the metal phosphate materials synthesis, [7][8][9][10] and iron phosphate with porous structure would be interesting in terms of structure and adsorbent performance.…”

Section: Introductionmentioning

confidence: 99%

Removal of Chromium Hexavalent Ions From Aqueous Solution by Retention Onto Iron Phosphate

Granados-Correa

Serrano-Gómez

2010

J. Chil. Chem. Soc.

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Iron phosphate was synthesized and characterized for the removal of Cr(VI) ions from aqueous solution. Batch type experiments were conducted to study the effects of contact time, pH of the solution, chromium concentration and temperature. The experimental data were analyzed with the adsorption isotherms models of Freundlich, Langmuir and Dubinin Radushkevich (D-R). Results showed that Cr(VI) retention is dependent on pH and temperature. The thermodynamic parameters of the retention system were determined in a temperature interval from 293-323 K. The obtained values of thermodynamic parameters show that the Cr(VI) ions retention on iron phosphate is endothermic and spontaneous type. The results suggest that iron phosphate could be used as an effective adsorbent for the retention of Cr(VI) ions from aqueous solution.

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Mechanism of Deposition of the CrO42-, HCrO4-, and Cr2O72- Ions on the .gamma.-Alumina Surface

Cited by 36 publications

References 11 publications

Adsorption monitoring of phospho-l-serine on hydroxyapatite

Adsorption monitoring of phospho-l-serine on hydroxyapatite

Modification by SiO2 of Alumina Support for Light Alkane Dehydrogenation Catalysts

Removal of Chromium Hexavalent Ions From Aqueous Solution by Retention Onto Iron Phosphate

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