Wood derived biochar as electron donor and its influence on microbial denitrification: Role of extracellular polymeric substances in extracellular electron transfer

2020 ◽  
Author(s):  
Kuppusamy Sathishkumar ◽  
Yi Li ◽  
Rana Muhammad Adnan Ikram
Keyword(s):  
Electron Transfer ◽  
Electron Donor ◽  
Electrochemical Behavior ◽  
Nitrate Reduction ◽  
Extracellular Polymeric Substances ◽  
Electrochemical Impedance ◽  
Electrochemical Analysis ◽  
Extracellular Electron Transfer ◽  
Microbial Denitrification

<p>Biochar is extensively used in environmental pollutant remediation because of its diverse property, however the effect of biochar on microbial nitrate reduction and electrochemical behavior of biochar remain unknown. Also electron transfer from the microbial cells to electron donor or acceptor have been transport across the extracellular polymeric substances (EPS), however it was unclear whether extracellular polymeric substances captured or enhance the electrons.  Hence, aim of the present study is to investigate the electrochemical behavior of biochar and its effects on microbial nitrate reduction and elucidate the role of extracellular polymeric substances in extracellular electron transfer (EET).  The biochar was prepared at different pyrolysis temperatures (400 °C, 500 °C and 600 °C) and their electrochemical behavior was characterized by electrochemical analysis (cyclic voltammetry, electrochemical impedance spectrum, chronoamperometry). Results demonstrated that all the biochars could donate and accept the electrons, impact of biochar on microbial nitrate reduction was studied and the results showed that biochar prepared at 400 °C significantly enhances microbial nitrate reduction process. Phenol O-H and quinone C=O surface functional groups on the biochar contributes in the overall electron exchange which accelerated the nitrate reduction. The role of EPS in EET by electrochemical analysis results reveals that outer membrane c-type cytochrome and flavin protein from the biofilm was involved in electron transfer process, and EPS act as transient media for microbial EET. Overall, present study suggested that biochar could be used as eco-friendly material for the enhancement of microbial denitrification.</p>

Impact of Graphitic Structures in Pyrogenic Carbon on Microbial Reduction of Ferrihydrite

2021 ◽  
Author(s):  
wentao yu ◽  
baoliang chen
Keyword(s):  
Electron Transfer ◽  
Pyrolysis Temperature ◽  
Shewanella Oneidensis ◽  
Exchange Capacity ◽  
Microbial Reduction ◽  
Systematic Evaluation ◽  
Extracellular Electron Transfer ◽  
Pyrogenic Carbon ◽  
The Impact

<p>Pyrogenic carbon plays important roles in microbial reduction of ferrihydrite by shuttling electrons in the extracellular electron transfer (EET) processes. Despite its importance, a full assessment on the impact of graphitic structures in pyrogenic carbon on microbial reduction of ferrihydrite has not been conducted. This study is a systematic evaluation of microbial ferrihydrite reduction by Shewanella oneidensis MR-1 in the presence of pyrogenic carbon with various graphitization extents. The results showed that the rates and extents of microbial ferrihydrite reduction were significantly enhanced in the presence of pyrogenic carbon, and increased with increasing pyrolysis temperature. Combined spectroscopic and electrochemical analyses suggested that the rate of microbial ferrihydrite reduction were dependent on the electrical conductivity of pyrogenic carbon (i.e., graphitization extent), rather than the electron exchange capacity. The key role of graphitic structures in pyrogenic carbon in mediating EET was further evidenced by larger microbial electrolysis current with pyrogenic carbon prepared at higher pyrolysis temperatures. This study provides new insights into the electron transfer in the pyrogenic carbon-mediated microbial reduction of ferrihydrite.</p>

Development of a novel palm fiber biofilm electrode reactor (PBER) for nitrate-contaminated wastewater treatment: performance and mechanism

2020 ◽  
Vol 6 (3) ◽  
pp. 839-850 ◽  
Author(s):  
Chen Yang ◽  
Chuanping Feng ◽  
Nan Chen ◽  
Yang Deng ◽  
Weiwu Hu ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Wastewater Treatment ◽  
Electrochemical Reduction ◽  
Nitrate Reduction ◽  
Extracellular Electron Transfer ◽  
Autotrophic Denitrification ◽  
Palm Fiber ◽  
Treatment Performance ◽  
Performance And Mechanism ◽  
Heterotrophic Denitrification

The main pathways for nitrate reduction are electrochemical reduction, heterotrophic denitrification, hydrogen autotrophic denitrification and extracellular electron transfer.

scholarly journals In-Situ Sensing of Microbial Growth Phases via Two-Terminal Cyclic Voltammetry

2020 ◽  
Author(s):  
Arindam Kushagra ◽  
Diyasa Bazal ◽  
Anup Kumar Pradhan ◽  
Pratyusha Ghosh ◽  
Akshaya Pandey
Keyword(s):  
Electron Transfer ◽  
Cyclic Voltammetry ◽  
Microbial Growth ◽  
Extracellular Polymeric Substances ◽  
Electrochemical Sensors ◽  
Extracellular Electron Transfer ◽  
Growth Phases ◽  
Electron Transfer Mechanism ◽  
Temporal Area ◽  
In Situ Sensing

Microbial growth has been of prime importance to the researchers in health and biotechnology industries. It has been known to be closely associated to the secretion of extracellular polymeric substances that help in the formation of colonies. Inter-microbial communication happens within such colonies by means of extracellular electron transfer mediated by the aforementioned polymeric substances. Conventionally, different phases of microbial growth are monitored with the aid of a traditional UV-Visible spectrophotometer by measuring the optical density of the liquid medium at 280 nm. In this paper, we have developed an alternative novel way to sense different growth phases employing electrochemical means i.e. two-terminal cyclic voltammetry. This cyclic voltammetry relies on the extracellular electron transfer mechanism taking place via the polymeric substances secreted by the microorganisms, measured by the temporal area changes in the current-voltage hysteresis curves in the inoculated nutrient broth. This work paves a new way to detect the biological activity in the medium, which can be directly correlated to the population of microorganisms. It would be of immense interest to scientists and researchers working in the field of microbiology as well as in development of biosensors, electrochemical sensors etc. which would be helpful in absence of traditional spectrophotometers.

scholarly journals Electrochemical Analysis of Architecturally Enhanced LiFe0.5Mn0.5PO4 Multiwalled Carbon Nanotube Composite

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Sabelo Sifuba ◽  
Shane Willenberg ◽  
Usisipho Feleni ◽  
Natasha Ross ◽  
Emmanuel Iwuoha
Keyword(s):  
Electron Transfer ◽  
Carbon Nanotube ◽  
Electrode Materials ◽  
Electrochemical Impedance ◽  
Electrochemical Analysis ◽  
Multiwalled Carbon Nanotube ◽  
Spectroscopic Techniques ◽  
Redox Potentials ◽  
Multiwalled Carbon ◽  
Iron Manganese

In this work, the effect of carbon on the electrochemical properties of multiwalled carbon nanotube (MWCNT) functionalized lithium iron manganese phosphate was studied. In an attempt to provide insight into the structural and electronic properties of optimized electrode materials, a systematic study based on a combination of structural and spectroscopic techniques was conducted. The phosphor-olivine LiFe0.5Mn0.5PO4 was synthesized via a simple microwave synthesis using LiFePO4 and LiMnPO4 as precursors. Cyclic voltammetry was used to evaluate the electrochemical parameters (electron transfer and ionic diffusivity) of the LiFe0.5Mn0.5PO4 redox couples. The redox potentials show two separate distinct redox peaks that correspond to Mn2+/Mn3+ (4.1 V vs Li/Li+) and Fe2+/Fe3+ (3.5 V vs Li/Li+) due to interaction arrangement of Fe-O-Mn in the olivine lattice. The electrochemical impedance spectroscopy (EIS) results showed LiFe0.5Mn0.5PO4-MWCNTs have high conductivity with reduced charge resistance. This result demonstrates that MWCNTs stimulate faster electron transfer and stability for the LiFe0.5Mn0.5PO4 framework, which demonstrates to be favorable as a host material for Li+ ions.

scholarly journals The role of the concentration profile of titanium oxide on the electrochemical behavior of RuO2-TiO2 coatings obtained by the sol-gel procedure

2003 ◽  
Vol 68 (12) ◽  
pp. 979-988 ◽  
Author(s):  
Vladimir Panic ◽  
Aleksandar Dekanski ◽  
Vesna Miskovic-Stankovic ◽  
Slobodan Milonjic ◽  
Branislav Nikolic
Keyword(s):  
Electrochemical Behavior ◽  
High Frequency ◽  
Electrochemical Impedance ◽  
Sol Gel ◽  
Tio2 Coating ◽  
Tio2 Layer ◽  
Low Frequencies ◽  
Tio2 Coatings ◽  
Overall Resistance

In order to understand the role of TiO2 in the deactivation mechanism of an active RuO2?TiO2 coating, an additional TiO2 layer was introduced in the support coating interphase of regular Ti//[RuO2?TiO2 anode in one case and on the surface of the coating in the other. The electrochemical behavior of these, with TiO2 enriched, anodes was compared with the behavior of anodes with regular RuO2?TiO2 coatings, which were subjected to an accelerated stability test. A high-frequency semicircle in the complex plane plot obtained by electrochemical impedance spectroscopy, for a regular RuO2?TiO2 coating corresponds to TiO2 enrichment in the coating as a consequence of anode corrosion. In the case of the coatings with additional TiO2 layers, a high-frequency semicircle was not observed. The additional TiO2 layers increase the coating overall resistance and influence the coating impedance behavior at low frequencies. Similar equivalent electrical circuits were used to analyze the impedance behavior of coatings having an additional TiO2 layer at different position within RuO2?TiO2 coating.

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