Electrochemical recycling of sodium borohydride for hydrogen storage : physicochemical properties of sodium metaborate solutions
The large-scale adoption of a "hydrogen economy" is hindered by the lack of a practical storage method and concerns associated with its safe handling. Chemical hydndes have the potential to address these concerns. Sodium borohydride (sodium tetrahydroborate, NaBH₄), is the most attractive...
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ndltd-UBC-oai-circle.library.ubc.ca-2429-179002018-01-05T17:39:10Z Electrochemical recycling of sodium borohydride for hydrogen storage : physicochemical properties of sodium metaborate solutions Cloutier, Caroliine R. The large-scale adoption of a "hydrogen economy" is hindered by the lack of a practical storage method and concerns associated with its safe handling. Chemical hydndes have the potential to address these concerns. Sodium borohydride (sodium tetrahydroborate, NaBH₄), is the most attractive chemical hydride for H₂ generation and storage in automotive fuel cell applications but recycling from sodium metaborate (NaB0₂) is difficult and costly. An electrochemical regeneration process could represent an economically feasible and environmentally friendly solution. In this thesis, the properties of diluted NaB0₂ aqueous solutions and concentrated NaB0₂ alkaline aqueous solutions that are necessary for the development of electrochemical recycling methods have been studied. The conductivity and viscosity of dilute aqueous solutions of NaB0₂ were measured as a function of concentration at 25°C. Also, the solubility, pH, density, conductivity and viscosity of the filtrate of saturated aqueous NaB0₂ solutions containing varying weight percentages (1, 2, 3, 5, 7.5 and 10 wt%) of alkali hydroxides (NaOH, KOH and LiOH) were evaluated at 25°C. Selected experiments were repeated at 50 and 75°C to investigate the effect of temperature on the NaB0₂ alkaline aqueous solution solubility and physicochemical properties. Preliminary experiments to investigate the effect of glycine (C₂H₅N0₂), the smallest amino acid, on the solubility and physicochemical properties of NaB0₂ alkaline aqueous solutions were conducted at 25°C. Furthermore, the precipitates formed in the supersaturated 10 wt% alkaline aqueous NaB0₂ solutions at 25°C were characterized by X-Ray Diffraction and Scanning Electron Microscopy. The use of KOH as the electrolyte was found to be more advantageous for the H₂ storage and generation system based on NaBO₂ solubility and NaBH₄ half-life due to the pH effect. However, the addition of NaOH led to the highest ionic conductivity, and its use seems more suitable for the electroreduction of NaB0₂. Further investigations on the impact of KOH and NaOH on the electroreduction of NaB0₂ in aqueous media have the potential to enhance the commercial viability of this H₂ generation and storage system. Applied Science, Faculty of Materials Engineering, Department of Graduate 2010-01-08T21:41:34Z 2010-01-08T21:41:34Z 2006 2006-11 Text Thesis/Dissertation http://hdl.handle.net/2429/17900 eng For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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English |
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The large-scale adoption of a "hydrogen economy" is hindered by the lack of a practical storage method and concerns associated with its safe handling. Chemical hydndes have the potential to address these concerns. Sodium borohydride (sodium tetrahydroborate, NaBH₄), is the most attractive chemical hydride for H₂ generation and storage in automotive fuel cell applications but recycling from sodium metaborate (NaB0₂) is difficult and costly. An electrochemical regeneration process could represent an economically feasible and environmentally friendly solution. In this thesis, the properties of diluted NaB0₂ aqueous solutions and concentrated NaB0₂ alkaline aqueous solutions that are necessary for the development of electrochemical recycling methods have been studied. The conductivity and viscosity of dilute aqueous solutions of NaB0₂ were measured as a function of concentration at 25°C. Also, the solubility, pH, density, conductivity and viscosity of the filtrate of saturated aqueous NaB0₂ solutions containing varying weight percentages (1, 2, 3, 5, 7.5 and 10 wt%) of alkali hydroxides (NaOH, KOH and LiOH) were evaluated at 25°C. Selected experiments were repeated at 50 and 75°C to investigate the effect of temperature on the NaB0₂ alkaline aqueous solution solubility and physicochemical properties. Preliminary experiments to investigate the effect of glycine (C₂H₅N0₂), the smallest amino acid, on the solubility and physicochemical properties of NaB0₂ alkaline aqueous solutions were conducted at 25°C. Furthermore, the precipitates formed in the supersaturated 10 wt% alkaline aqueous NaB0₂ solutions at 25°C were characterized by X-Ray Diffraction and Scanning Electron Microscopy. The use of KOH as the electrolyte was found to be more advantageous for the H₂ storage and generation system based on NaBO₂ solubility and NaBH₄ half-life due to the pH effect. However, the addition of NaOH led to the highest ionic conductivity, and its use seems more suitable for the electroreduction of NaB0₂. Further investigations on the impact of KOH and NaOH on the electroreduction of NaB0₂ in aqueous media have the potential to enhance the commercial viability of this H₂ generation and storage system. === Applied Science, Faculty of === Materials Engineering, Department of === Graduate |
author |
Cloutier, Caroliine R. |
spellingShingle |
Cloutier, Caroliine R. Electrochemical recycling of sodium borohydride for hydrogen storage : physicochemical properties of sodium metaborate solutions |
author_facet |
Cloutier, Caroliine R. |
author_sort |
Cloutier, Caroliine R. |
title |
Electrochemical recycling of sodium borohydride for hydrogen storage : physicochemical properties of sodium metaborate solutions |
title_short |
Electrochemical recycling of sodium borohydride for hydrogen storage : physicochemical properties of sodium metaborate solutions |
title_full |
Electrochemical recycling of sodium borohydride for hydrogen storage : physicochemical properties of sodium metaborate solutions |
title_fullStr |
Electrochemical recycling of sodium borohydride for hydrogen storage : physicochemical properties of sodium metaborate solutions |
title_full_unstemmed |
Electrochemical recycling of sodium borohydride for hydrogen storage : physicochemical properties of sodium metaborate solutions |
title_sort |
electrochemical recycling of sodium borohydride for hydrogen storage : physicochemical properties of sodium metaborate solutions |
publishDate |
2010 |
url |
http://hdl.handle.net/2429/17900 |
work_keys_str_mv |
AT cloutiercaroliiner electrochemicalrecyclingofsodiumborohydrideforhydrogenstoragephysicochemicalpropertiesofsodiummetaboratesolutions |
_version_ |
1718590676654882816 |