Dissertation
Thermodynamics of Layered Double Hydroxides for Removal of Iodine Species from Aqueous Media
Washington State University
Doctor of Philosophy (PhD), Washington State University
2023
DOI:
https://doi.org/10.7273/000005028
Abstract
Nuclear energy has the potential to provide sufficient clean energy to replace fossil fuels and reduce carbon dioxide emissions. However, significant health and environmental concerns surround nuclear power plants. Radioiodine is a major fission product of uranium (~3 wt%) iodine-131 (131I) has a half-life of 1.6 x 107 years and iodine-129 (129I) has a half-life of 8 days and is a high energy gamma radiator (364 KeV). Furthermore, iodine is highly environmentally mobile, specifically as the iodide (I-) and iodate (IO3-) anions, and therefore poses a great risk to humans. Although the iodate anion makes up the majority of iodine species (~70.6 %) at the Hanford Tank Waste Treatment and Immobilization Plant in Washington, United States, the focus for iodine capture and detection studies has mainly been on elemental iodine (I2) and organoiodides. Layered materials such as layered double hydroxides (LDHs) have great potential to both adsorb and detect iodine from aqueous waste. The positively charged layers of LDHs require charge balancing anions in the interlayer, thus we can use the interlayer space to confine iodine anions within the LDH structure. LDHs are battery-like capacitor materials with redox by an insertion mechanism, they possess pseudocapacitive charge storage capabilities. Their electrochemical properties open the door to sensing applications that could aid in the detection of radioiodine from the environment. This work will outline the following main findings (i) structural degradation is observed upon insertion of iodine into the interlayer of NiAl-LDH structure, (ii) iodide confined in the interlayer of NiAl-LDH, causes the formation to become more energetically stable by 46.16 kJ/mol LDH, whereas the formation of iodate confined NiAl-LDH becomes less energetically stable by 121.47 kJ/mol LDH compared to the NiAl-LDH with no iodine confined, (iii) the mechanism for binding iodine within the interlayer of NiAl-LDH differs from I- to IO3- yet both interfacial bonding mechanisms present high thermal stabilities above 340℃ under oxidative gas, and (iv) the specific capacitance of NiAl-LDH is observed to decrease by 274.13 Fg-1 and 427.13 Fg-1 when I- and IO3- respectively are present in the interlayer.
Metrics
17 File views/ downloads
80 Record Views
Details
- Title
- Thermodynamics of Layered Double Hydroxides for Removal of Iodine Species from Aqueous Media
- Creators
- Megan Rose Hawkins
- Contributors
- Di Wu (Advisor)Ursula Mazur (Committee Member)Xiaofeng Guo (Committee Member)Qiang Zhang (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Chemistry
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 157
- Identifiers
- 99901019635101842
- Language
- English
- Resource Type
- Dissertation