Structure and Dynamics of Layered Double Hydroxides

Layered double hydroxides (LDHs) are a complex group of phases with wide ranging technological applications and increasingly recognized geochemical significance. They are unusual among oxide and hydroxide phases in having large anion exchange capacities, and enhancing their application and understanding their geochemical significance require better understanding of the interlayer and surface structure and dynamics of anions and water molecules. This thesis describes a systematic experimental investigation of the hydration, expansion, and molecular scale structure and dynamics of LDHs. It provides important, fundamental data and significant new insight into the factors that control the observed structural and dynamic behavior. The diversity of LDHs allows incorporation of many NMR-observable nuclei and thus systematic investigation of the effects of such parameters as anionic size, charge, and configuration on the structure and dynamics. I have synthesized a wide variety of LDHs containing the cations Mg,Al and Li,Al in the octahedral layers and anions including 13CO32-, 15NO 3-, 77SeO42- , 77SeO32-, 35ClO4-, 35Cl -, H31PO42-, 31PO43- and many others. These samples were examined with NMR, XRD, TGA and water gravimetry under well-controlled relative humidity conditions or/and over a wide temperature range. The results show that LDHs have widely variable hydration, expansion, structural and dynamical behaviors that depend on the anion size, charge, and configuration, and on the hydroxide-layer composition. The results illustrate clearly how NMR spectroscopy combined with XRD, water sorption and thermogravimetric (TGA) data can effectively probe these properties and provide a basis for understanding the interaction and relationships among these properties. Chapter 1.3 provides a detailed summary of the principal results.

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

2015

Author dc:creator

• Hou, Xiaoqiang

Contributors dc:contributor

• Kirkpatrick, R. James

• Chemistry, Nuclear

Language dc:language

eng

Identifier

(MiAaPQ)AAI3030438

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/86519