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3. Fuel Cell Institute / Institut Sel Fuel

Title:	Development of a sulphate reducing bacteria based biocathode for hydrogen production in a full biological microbial electrolysis cell
Authors:	Tahereh Jafari (P69309)
Supervisor:	Wan Ramli Wan Daud, Prof. Dato' Ir. Dr.
Keywords:	Hydrogen Biocathode Hydrogen as fuel
Issue Date:	1-Mar-2018
Description:	Microbial electrolysis cells (MECs) have rapidly evolved as a promising technology to produce hydrogen from organic matter. To produce clean hydrogen in an MEC, both anodic and cathodic reactions should be catalyzed biologically. The MEC bioanode enrichment strategy is already known. However, the performance needs to be improved. The MEC cathode has a rate limiting effect on the hydrogen evolution reaction (HER) in the MEC due to its overpotential which has previously been overcome by using expensive noble metal catalysts. Microorganism attached to the cathode, known as biocathode, is a promising alternative to abiotic catalysts for hydrogen production. Sulphate-reducing bacteria (SRB) have been discussed and hypothesised in the literature as a potential source for biocathode enrichment but this has not been studied for hydrogen production in an MEC biocathode. The objectives of this study are to develop an SRB-based biocathode and enhance the hydrogen production rate (HPR) in a half biological MEC (HB-MEC) setup, to study hydrogen production in a full biological MEC (FB-MEC) and to characterise the enriched biocathodes in terms of their morphology and microbial communities. Moreover, the mode of operation to have an efficient bioanode has been investigated in a conventional microbial fuel cell (MFC) system and was applied to the anode of the FB-MEC. Therefore, the SRB were enriched through ex-situ and in-situ enrichment stages in two experimental configurations, i.e. polarity reversal of an MFC anode to an MEC biocathode (MFC-MEC) and originally development of an MEC biocathode (MEC-O) in HB-MEC. The anode mode of operation was studied in a HB-MFC. Subsequently the developed bioanode and biocathode were transferred to a FB-MEC. Furthermore, the developed biocathodes were examined by scanning electron microscopy (SEM). The DNA of the microbial communities attached to the biocathodes was then extracted and the dominant communities identified in detail using metagenomic amplicon sequencing. Hydrogen was the main product of the MEC-O biocathode while methane was detected as the sole product of the MFC-MEC biocathode system. Based on the results of these experiments, the MEC-O configuration was selected for further performance enhancement stage. The biocathode development procedure was comprehensively studied concerning the effective parameters of sulphate content, H2-rich environment and pH consecutively. The results showed that the HER onset potential decreased from -1.18 to -0.84 V and charge transfer resistance (Rct) declined from 6.2 to 1.56 Ώ and HPR increased to 1.85 m3/(m3.d) in the biocathode system during the enhancement stages. The results were at reasonably comparable levels with those obtained for the conventional Pt-cathode MEC which were -0.69 V, 1.22 Ώ and 2.7 m3/(m3.d) respectively. The entire biocathode development stages had achieved a 430-mV reduction of HER onset potential, 300 times reduction of Rct and moreover, about 6 times increment in HPR compared to those of the non-inoculated plain graphite felt cathode. The recirculation batch mode of operation showed the highest result in the mode of operation study and the FB-MEC setup. Desulfovribio was detected as the dominant genus in the enriched biocathode. Taken together, the results showed that the developed FB-MEC produced cleaner hydrogen due to the cheaper, more environmentally friendly and self-generative characteristics of enriched biocatalyst compared to the expensive, non-renewable, scarce and easily poisoned abiotic catalysts.,Certification of Master's/Doctoral Thesis" is not available
Pages:	164
Call Number:	TD359.H8J336 2018 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Fuel Cell Institute / Institut Sel Fuel

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