Doctoral Dissertations
Abstract
"Borate glasses have been developed for biomedical applications such as scaffolds for soft tissue and bone repair. The dissolution processes of borate glasses in phosphate-containing aqueous solutions were studied by µ-Raman spectroscopy which provided information about the types and concentrations of borate species released into the solution as a function of time and characterized the formation of calcium phosphate reaction products on the glass surface. Boric acid molecules (H3BO3) and borate anions (B(OH)4-) can be detected in solution and their relative concentrations depend on the solution pH.
Static and dynamic single-pass flow-through experiments were employed to study the dissolution kinetics of a borate bioactive glass 13-93B3 in water, simulated body fluid (SBF), and other solutions. As the glasses react, B-, Ca-, Na-, K-, Mg-, and P-species were released from the glass and a magnesium-containing amorphous calcium phosphate (ACP) or hydroxyapatite (HAP) layer formed on the surface of the glass. The formation of crystalline hydroxyapatite was favored with faster flow rates, longer reaction times, and increased phosphate concentration in solution. Under static conditions, the dissolution rates are initially described by a reaction-controlled model (linear kinetics), but after the glass is ~25-30% reacted, a diffusion-controlled model (parabolic kinetics) better describes the dissolution rates. The change in reaction mechanism is attributed to the diffusion of species from the glass through the ACP layer. The activation energy for the reaction-controlled process is 41.1±0.6 kJ/mol, whereas the activation energy for the diffusion process is 32.3±0.1 kJ/mol. For the SPFT experiments, glasses dissolved faster under faster flow rates and smaller glass volumes. The ion release rate was calculated and found to range from 1.7x10-5 g/m2/s for slow flow rates to 1.1x10-3 g/m2/s for lower glass volumes."--Abstract, page iv.
Advisor(s)
Brow, Richard K.
Committee Member(s)
Day, D. E.
Fahrenholtz, William
Schlesinger, Mark E.
Wronkiewicz, David J.
Department(s)
Materials Science and Engineering
Degree Name
Ph. D. in Materials Science and Engineering
Sponsor(s)
National Science Foundation (U.S.)
Missouri University of Science and Technology. Center for Biomedical Science and Engineering
Publisher
Missouri University of Science and Technology
Publication Date
Spring 2015
Journal article titles appearing in thesis/dissertation
- In-situ characterization of borate glass dissolution kinetics by µ-Raman spectroscopy
- Dissolution of a bioactive borate glass under static conditions
- In-vitro dissolution of a bioactive borate glass under dynamic conditions
- Nanocrystalline rare earth phosphates from glass dissolution and precipitation reactions
Pagination
xiv, 176 pages
Note about bibliography
Includes bibliographic references.
Rights
© 2015 Jaime Lynn George, All rights reserved.
Document Type
Dissertation - Open Access
File Type
text
Language
English
Subject Headings
Glass -- ResearchBoratesHydroxyapatitePhosphates
Thesis Number
T 10712
Electronic OCLC #
913391303
Recommended Citation
George, Jaime Lynn, "Dissolution of borate glasses and precipitation of phosphate compounds" (2015). Doctoral Dissertations. 2382.
https://scholarsmine.mst.edu/doctoral_dissertations/2382
Comments
This research was supported by the National Science Foundation under grant numbers DMR-0305202 and DMR-1207520