| Abstract [eng] |
With increasing human needs and a growing world population, the earth is facing many global challenges. With the rapid expansion of the industrial sector and the meeting of the ever-growing market needs, the damage caused to nature is often overlooked. For this reason, new technologies that address issues of freshwater scarcity, the use of non-renewable electricity or the pollution of natural ecosystems with toxic waste are of growing interest in conserving natural resources. One of the technologies producing sustainable “clean” energy is microbial fuel cells (MFC), in which exoelectrogens are able to directly generate electricity from organic materials. Exoelectrogens, e.g. Shewanella putrefaciens bacteria, are able to pass electrons, which are released during bacteria metabolism processes, while decomposing organic matter to the anode in MFC. Through the anode, electrons enter a closed electrical circuit and move to the cathode. Thus, useful electrical work is done. The electricity generated in this way is not only "clean", but also enables the removal of organic matter from polluted wastewater. MFC can also be used as biological sensors if favorable conditions for microorganisms or enzymes are assured. Due to its advantages and wide application, this innovation is receiving more and more attention from scientists. The voltage generated by the two-chamber microbial fuel cells is highly dependent on the properties of electrodes, microorganisms, medium and the design used. A culture of Shewanella putrefaciens bacteria was used as exoelectrogens in the anode chamber. During the study, graphite fiber felt (GFF) was electrochemically oxidized and modified with different organic amines. Four different organic amines were used in the experiments: m-xylylenediamine, 2,4-diaminotoluene, 3-amino-1,2,4-triazole, and 3-aminopyridine. Microbial fuel cells with anodes made of the samples of modified GFFs were assembled and their generated voltage was recorded in long-term studies with and without aeration of the catholyte. The results of the investigation revealed, that the highest voltage was generated by MFC with anode made from GFF modified with 2,4-diaminotoluene. It should be noted, that all MFC with anodes made from modified GFF maintained higher and more stable voltage without catholyte aeration in comparison with the MFC utilizing a bare GFF as an anode. Extremely constant voltage was generated by the MKE, which anode was modified with m-xylenediamine. Voltage generated by this MFC varied within ± 1 mV over 20 h period. It can be stated, that nitrogen-containing compound fragments attached to the anode in a microbial fuel cell increase the magnitude and stability of the generated voltage. During the project, the influence of the different concentration of NaCl in bacteria nutrient media used as anolyte in MFCs was determined. It has been shown, that increasing the sodium chloride concentration to 22 g/l in the MFC anolyte medium, resulted in the increased voltage generated by MFC. |
