Determining the lon-exchange Mechanism of Strontium into a Niobium Doped Titanosilicate

<p>A 25% niobium substituted sitinakite was exchanged with strontium as time resolved X-ray diffraction data was collected. The structural modeling of this data by Rietveld method1 has lead to the determination of the atomic positions of the ions and unit cell parameters as strontium occupancy increases.</p> <p>The starting material of the exchange experiment is the protonated phase, H2Nb0.67Ti1.33SiO7·1.9 H2O, with space group P42/mcm2,3. Once strontium (Sr2+) enters the unit cell, extra-framework H2O molecules shift to provide the necessary hydration coordination. These new positions of H2O result in a lowering of symmetry to the P-42m space group, and it is thought that the new hydrogen bonding network serves to enhance strontium ion diffusion into the channels of sitinakite. Exchange of strontium into the microporous material reaches a maximum fractional occupancy of 21% when a 10.0 mM strontium ion solution is forced over the powdered material. Sequestration of strontium into this material has contributed valuable information to the study of microporous materials and ion exchange chemistries.</p>

Name thesis:degree_name

Master of Science

Discipline thesis:degree_discipline

Department of Geography and Geology

Year

2011

Author dc:creator

• Kramer, Samantha Jane

Contributors dc:contributor

• Dr. Aaron Celestian (Director), Dr. Les Pesterfield, Dr. Michael May, Dr. Andrew Wulff

• ion exchange
• zeolites
• sequestration
• X-ray diffraction
• WKU‟s Advanced Materials Institute
• Environmental Chemistry
• Environmental Indicators and Impact Assessment
• Geochemistry

Repository record dc:identifier

https://digitalcommons.wku.edu/theses/1068

OAI identifier oai:identifier

oai:digitalcommons.wku.edu:theses-2072