Performance and kinetic study of photo microbial fuel cells (PMFCs) with various conditions

• Main Authors: KUMARAN RAMAN, 古馬丁
• Other Authors: JohnChi-WeiLan
• Format: Others
• Language: en_US
• Online Access: http://ndltd.ncl.edu.tw/handle/52692205048571007108

碩士 === 元智大學 === 生物科技與工程研究所 === 100 === The concern about global warming effects and fossil fuel costs has encouraged the search for alternative sources of energy. Microbial fuel cell (MFC) offers an alternative way to obtain bio-electricity by oxidizing organic materials using microorganisms as biocatalysts. Many microorganisms such as Clostridium sp., Shewanella sp. and some photosynthetic microorganisms have been applied as microbial catalysts for driving MFC devices. My thesis is divided into two parts where in the first part I investigated the advantage of Chlamydomonas reinhardtii transformation F5-1 over the wild type strain. Chlamydomonas reinhardtii transformation F5-1 is a genetically modified strain where the ferredoxin 5 (F5) isoform is over expressed. In this part I found out that Chlamydomonas reinhardtii transformation F5-1 is better than wild type only when it is cultivated during light condition. Other test such as effect of acetic acid addition in culture broth every day shows that Chlamydomonas reinhardtii transformation F5-1 is better than wild type. Besides that, I also investigated the effect of different acetic acid concentration (25 mM, 50 mM, 100 mM, 200 mM) as carbon source on the Chlamydomonas reinhardtii transformation F5-1 cells growth. The results showed that Chlamydomonas reinhardtii transformation F5-1 grows better in 25 mM acetic acid. In the second part I investigated the performance and kinetic study of photo microbial fuel cells (PMFCs) with various conditions. First I tested the PMFC with different electrode distances. The electrode distances applied in this study were 10.3, 12.5 and 14.7 cm. Higher power density and lower internal resistance were observed at electrode density 14.7 and 10.3 cm compare to at electrode distance 12.5 cm. Besides that, higher exchange current density (io) and over potential (ƞ) but lower electron transfer coefficient (β) can be observed at electrode density 14.7 and 10.3 cm compare to at electrode distance 12.5 cm. In addition we also performed experiment with different stirring speed and found out that power density increased and internal resistance decreased with increasing stirring speed. Secondly I tested the PMFC with rough anode surface electrode. The results showed that higher power density and lower internal resistance can be obtained using rough anode surface electrode. Besides that higher exchange current density (io) and lower over potential (ƞ) can be observed at electrode density 14.7 and 10.3 cm compare to at electrode distance 12.5 cm. Thirdly I tested the PMFC with different anode electrolyte pH value. The pH values used were 5.8, 8 and 10. The results showed that higher power density can be obtained at pH 8 value but the internal resistance value is slightly higher than at ph 5.8. Besides that higher exchange current density (io) and lower over potential (ƞ) can be observed at pH 8 compare to at ph 5.8 and 10. The performance of PMFC started to decrease at pH 10 maybe due to high accumulation of OH- ions. Fourthly, PMFC were operated continuously by adding 80 mM salt (NaCl) for three days. The results showed that higher power density and lower internal resistance can be obtained on the third day of PMFC operation (240 mM). Besides that higher exchange current density (io) and lower over potential (ƞ) can be observed on the third day. In addition, the survival rate (%) of Chlamydomonas reinhardtii transformation F5-1 in the anode chamber decreased to 26.92 % on the third day of PMFC operation. Finally, I investigated the performance of PMFC under various blue and red LED light intensities (100 Lux, 300 Lux, 600 Lux and 900 Lux). Besides that, the effects of various blue and red LED light intensities on chlorophyll formation were also observed. The results showed that red LED light with light intensity of 900 Lux is more suitable for Chlamydomonas reinhardtii transformation F5-1 because higher power density and lower internal resistance can be achieved. Besides that higher exchange current density (io) and lower over potential (ƞ) can be observed at this light intensity. Not only that, blue LED light doesn’t show a clear effect on chlorophyll formation but clear patent can be observed using red LED light.