The structural environments of cations adsorbed onto clays: A cesium-133 MAS NMR spectroscopic study

Chapter I investigates the local structural environment of adsorbed cations on the mineral hectorite using $\sp{133}$Cs Variable-Temperature Magic-Angle-Spinning Nuclear Magnetic Resonance (VT-MAS NMR) spectroscopy. The results show that Cs on hectorite occurs in several distinctly different chemical environments, and that motional averaging of Cs between some of these sites occurs above ${\sim}{-}40\sp\circ$C if water is present in the interlayer. Above ${\sim}{-}10\sp\circ$C, spectra for slurries of hectorite in CsCl solutions yield two peaks, one due to Cs in solution, and the other due to Cs motionally-averaged on the clay. Below ${\sim}{-}60\sp\circ$C, motional averaging of the adsorbed Cs slows sufficiently to allow resolution of two peaks representing different Cs-environments on the clay. The Stern-Gouy model is employed to explain these peaks and assign one to Cs in the Stern layer (relatively tightly bound to the basal oxygens), and the other to Cs in the Gouy diffuse layer. Between ${\sim}{-}60$ and $-10\sp\circ$C peaks for these two sites and a motionally-averaged peak are present. Cs-exchanged hectorite dehydrated at 500$\sp\circ$C yields peaks for two different sites on the clay, interpreted to be highly coordinated site (probably 12), and a less coordinated site (possibly 9), both in the interlayer.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Geology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Weiss, Charles Arthur, Jr

Contributors dc:contributor

• Kirkpatrick, R. James

• Mineralogy
• Geochemistry

Statement dc:rights

• Copyright 1989 Weiss, Charles Arthur, Jr

Language dc:language

eng

Identifier

AAI9011071
(UMI)AAI9011071

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/21845