碩士 / 國立清華大學 / 工程與系統科學系 / 105 / Since 1980s, the average of global temperature increased year by year due to burning lots of fossil fuel caused a huge amount of carbon dioxide emission. Carbon capture and storage system (CCS) was developed in order to decrease the amount of carbon dioxide in atmosphere, yet its operation cost was high. Therefore, we can utilize plants doing photosynthesis to absorb the carbon dioxide in atmosphere. Microalgae have greater photosynthesis efficiency and growing rate compared to other kinds of plants; meanwhile, carbon was the most element in microalgae composition and most of the carbon needed when it growing was absorbing carbon dioxide from the air. Therefore, microalgae has great potential for capturing carbon dioxide. Furthermore, biomass of microalgae can be made for other valuable products, such as biofuel or medicine. However, the growing environment influenced the pathway of microalgae’s metabolism, influencing the growth of microalgae. Therefore, the growing environment parameter of microalgae should be optimized in order to gain highest carbon dioxide capturing efficiency. In this research, few electrochemical sensors was developed to monitor the concentration of dissolved oxygen and pH value of the environment during microalgae growing. Dissolved carbon dioxide sensor was set to calculate the amount of carbon dioxide consumed by microalgae.
Ag/AgCl film electrode was used as reference electrode in electrochemical measuring system in this research. The potential of Ag/AgCl film was -4.97 ±0.90 mV in 20 days. Usually, microalgae achieved stationary phase in 3 to 4 days. Therefore, the Ag/AgCl film was stable enough for being reference electrode in micro-bioreactor.
Iridium oxide electrode was used as sensing electrode in pH sensor. The open circuit potential between iridium oxide electrode and reference electrode changed by the amount of hydrogen ion in solution. The stability could be enhanced by using graphene oxide as the protected layer to prevent it from contaminated by environment. The potential of the senor and pH vale have great linear relationship in the range of pH4 to pH7.
Gold electrode was used as dissolved oxygen sensor. By applying potential on gold, oxygen was forced to reduce to water. Therefore, the concentration of dissolved oxygen could be known by the reduce current. The stability could be enhanced by coating Nafion as electrolyte layer and coating PDMS as gas permeable layer. The amount of reduce current and the concentration of dissolved oxygen have great linear relationship in the range of 2 to 9 g DO/mL..
While carbon dioxide was absorbed by the polyethylenimine selective layer of the sensor, carbon became carbonic acid and released hydrogen ion which was latter doped in the polyaniline layer. The hydrogen ion doped in polyaniline layer was detect by the beneath iridium oxide electrode. However, the carbon dioxide sensor was not yet for on-chip detection. It needed more analysis and improvement in order to being functional.
| Identifer | oai:union.ndltd.org:TW/105NTHU5593078 |
| Date | January 2017 |
| Creators | Chen, Hung-Yu, 陳竑宇 |
| Contributors | Wang, Hsiang-Yu, 王翔郁 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 77 |
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