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Mobility and Reactions of VO2+ on Hydrated Smectite Surfaces

Published online by Cambridge University Press:  01 July 2024

Murray B. McBride
Murray B. McBride*
Affiliation:
Department of Agronomy, Cornell University, Ithaca, New York 14853
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Abstract

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The electron spin resonance (ESR) spectra of varying quantities of vanadyl ion (VO2+) adsorbed on hydrated hectorite indicated that hydrolysis of VO2+ was promoted at low levels of adsorption. The hydrolyzed product was adsorbed on the clay surfaces, with a ligand environment that was partially aqueous and partially hydroxide in nature. Greater amounts of VO2+ adsorbed on wetted hectorite obscured the ESR spectrum of the strongly adsorbed hydrolysis product with a solutionlike spectrum. An approximately 50% reduction in rotational mobility of VO2+ relative to solution was indicated by the linewidth of this spectrum. Loss in mobility occurred with reduction of the interlamellar spacing until, under strongly dehydrating conditions, the VO(H2O)52+ ions became aligned with the V=O bond axis normal to the plane of the clay platelets.

Резюме

Резюме

Электронный спинный резонансный (ЭСР) спектр различных количеств ионов ванадила (VO2+), адсорбированного гидратным гекторитом, указывал, что гидролиз VO2+ ускорялся на низких уровнях адсорбции. Гидролизный продукт адсорбировался на поверхностях глины в среде лиганда, который частично был водным, и частично гидроокисным по природе. Большие количества VO2+, адсорбированные на влажном гекторите, затемняли ЭСР спектр сильно адсорбированного гидролизного продукта с растворо-подобмным спектром. Приблизительно 50% уменьшение в ротационной мобильности VO2+ по отношению к раствору определялось линейной шириной этого спектра. Потеря мобильности происходила с уменьшением межслойных промежутков до тех пор пока в условиях сильной дегидратации ионы VO(Н2O)52+ выравнивались с осями связи V=O, нормальными к плоскости пластинок глины.

Resümee

Resümee

Die ESR Spektren verschiedener Mengen von Vanadylion (VO2+), adsorbiert auf hydriertem Hektorit, deutet an, daß Hydrolyse von VO2+ bei niedrigen Adsorptionsstufen angeregt wird. Das hydrolisierte Produkt war an der Tonoberfläche adsorbiert, mit einer Ligandenumgebung, die zum Teil wässrig und zum Teil hydroxydhaltig war. Größere Mengen von VO2+, welche auf angenäßtem Hektorit adsorbiert waren, verunklaren das ESR Spektrum des stark adsorbiertem Hydrolyseprodukts mit einem lösungsähnlichen Spektrum. Die Signalweite dieses Spektrums deutete eine etwa 50% Verminderung der rotationalen Beweglichkeit des VO2+ im Verhältnis zu lösungen an. Der Verlust in Beweglichkeit ereignete sich während der Reduktion der interlamellaren Abstände bis unter stark dehydrierenden Bedingungen die VO(H2O)52+ Ionen nach der V=O Bindungsachse ausgerichtet wurden, senkrecht zur Ebene der Tonplättchen.

Résumé

Résumé

Les spectres de spin d’électrons (ESR) de quantités variés d'ions de vanadyl (VO2+) adsorbée sur de l'hectorite hydratée ont indiqué que l'hydrolyse de VO2+ était promue à des niveaux d'adsorption peu élevés. Le produit hydrolysé était adsorbé sur les surfaces argileuses, avec un environment liant qui était de nature partiellement hydroxide et partiellement aqueux. De plus grandes quantités de VO2+ adsorbées sur de l'hectorite mouillée ont obscurci le spectre ESR du produit d'hydrolyse fortement adsorbé par un spectre semblable à celui d'une solution. La largeur de la ligne de ce spectre a indiqué une réduction d'approximativement 50% de la mobilité de rotation de VO2+ relative à une solution. La perte de mobilité a été de pair avec une réduction de l'espacement interlamellaire jusqu’à ce que, sous des conditions fortement déshydratantes, les ions VO(H2O)52+ s'alignent avec l'axe de liaison V=O, normal au plan des plaquettes argileuses.

Keywords

AdsorptionESRSmectiteVanadium
Type
Research Article
Information
Clays and Clay Minerals , Volume 27 , Issue 2 , April 1979 , pp. 91 - 96
Copyright
Copyright © 1979, The Clay Minerals Society

Footnotes

1

Contribution of the Department of Agronomy, Cornell University, Ithaca, N.Y. 14853. Agronomy Paper No. 1251.

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