The extracellular electron transfer (EET) mechanism of an isolated Gram-positive Bacillus megaterium strain (LLD-1), identified by 16S rRNA gene sequencing and physiological analysis, was investigated in the present study. The electrochemical activity of strain LLD-1 was confirmed by electrochemical E-t and amperometric I-t tests. Flavins in culture suspension from strain LLD-1 were further proved to be able to act as electron shuttles, strengthening the electron transfer from LLD-1 to the electrode. The output voltage and current output were increased 2.8 times and 3.7 times, respectively, by adding 100nM exogenetic flavins into microbial fuel cells inoculated with LLD-1. Electricity generation by LLD-1 from different carbon sources can be enhanced by adding 100nM exogenetic flavins. This study indicated that flavins were essential to the EET process of the Gram-positive strain LLD-1. Furthermore, a putative EET model for B. megaterium strain LLD-1 and even for Gram-positive bacteria was proposed.

The storage behavior and process of the first delithiation-lithiation of LiCoO2 cathode were investigated by electrochemical impedance spectroscopy (EIS). The electronic and ionic transport properties of LiCoO2 cathode along with variation of electrode potential were obtained in 1 mol.L-1 LiPF6-EC: DMC: DEC electrolyte solution. It was found that after 9 h storage of the LiCoO2 cathode in electrolyte solutions, a new arc appears in the medium frequency range in Nyquist plots of EIS, which increases with increasing the storage time. In the charge/discharge processes, the diameter of the new arc is reversibly changed with electrode potential. Such variation coincides well with the electrode potential dependence of electronic conductivity of the LiCoO2.. Thus this new EIS feature is attributed to the change of electronic conductivity of LixCoO2 during storage of the LiCoO2 cathode in electrolyte solutions, as well as in processes of intercalation-deintercalationtion of lithium ions. It has been revealed that the reversible increase and decrease of the resistance of SEI film in charge-discharge processes can be also ascribed to the variation of electronic conductance of active materials of the LiCoO2 cathode

Biomass pretreatment is a promising technology for reducing pollutants emitted by coal power plants and reducing coal usage. Pretreatment technologies (e.g., torrefaction and ashcontent, which greatly improves less technology) alter the physicochemical properties of raw biomass, such as empty fruit bunch (EFB), and affect its combustion characteristics. In this study, the combustion and emission characteristics of two pretreated biomass fuels mixed with coal in a 500 MW tangentially fired boiler are evaluated by simulation. The results show that the pretreated fuel maintains stable combustion in the boiler under different cofiring ratios. Further, biomasses containing highly volatile substances promote the ignition of coal and increase its burnout rate. The burnout rate of cofired torrefied EFB (T-EFB) is slightly lower than that of ashless EFB (A-EFB). Compared with pure coal combustion, at a cofiring ratio of 30%, the unburned carbon (UBC) concentrations of T-EFB and A-EFB decrease by approximately 9.3 and 52%, respectively. Gas emission measurements (NO X and SO X ) indicate that the pretreated biomasses significantly reduce air emissions. A cofiring ratio of 30% reduces NO X and SO X by approximately 30%. However, T-EFB shows a slightly better performance in terms of NO X reduction, which is known to be dependent on a lower peak gas temperature during combustion. At the same cofiring ratio, the furnace exit gas temperature (FEGT) for cofired A-EFB increases significantly (a maximum increase of approximately 70 K), resulting in a broad and potentially dangerous temperature deviation. The pretreated biomass cofiring conditions reduce the boiler load by no more than 2% compared with the pure coal case. Thus, when combustion characteristics, safe operating conditions, and pollutant emissions are considered, the optimal cofiring ratios of T-EFB and A-EFB with bituminous coal are 30% and only 10%, respectively.

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