Improvement in methanogenesis by incorporating transition metal nanoparticles and granular activated carbon composites in microbial electrolysis cells

Kim, Kyeong-Rok; Kang, Jun; Chae, Kyu-Jung

doi:10.1016/j.ijhydene.2017.06.142

Cited by 49 publications

(24 citation statements)

References 32 publications

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“…Granular active carbon and zero-valent iron have been employed to accelerate the start-up of biocathodes and upgrade electromethanogenesis efficiency (20)(21)(22). One such a study however showed that electromethanogenesis was not affected by magnetite amendment in comparison with magnetite-free reactors (20).…”

Section: Discussionmentioning

confidence: 99%

“…The performance of electromethanogenesis could be improved by introducing supplemental materials that are optimized for cathode electron transfer or that can efficiently catalyze H 2 evolution at low potentials (20)(21)(22). Iron oxide minerals such as magnetite are common in soils (23)(24)(25)(26)(27).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies on electromethanogensis often collected inoculants from anaerobic digesters. Anaerobic digesters specialized in industry may limit the diversity of methanogens (1, 14, 15, 21, 22, 32), while natural environments such as paddy soil or wetlands can harbor a wider variety of methanogens (33) and hence offer an opportunity to screen methanogens capable of efficient electromethanogenesis. In the present study, electromethanogenic reactors were constructed using an inoculum obtained from a rice paddy soil.…”

Section: Introductionmentioning

confidence: 99%

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Response of methanogen community to elevation of cathode potentials in the presence of magnetite

Gao

Wang

Huang

et al. 2020

Preprint

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Electromethanogenesis refers to the process where methanogens utilize electrons derived from cathodes for the reduction of CO2 to CH4. Setting of low cathode potentials is essential for this process. In this study, we test if magnetite, an iron oxide mineral widespread in environment, can facilitate the adaption of methanogen community to the elevation of cathode potentials in electrochemical reactors. Two-chamber electrochemical reactors were constructed with inoculants obtained from a paddy field soil. We elevated cathode potentials stepwise from the initial −0.6 V vs standard hydrogen electrode (SHE) to −0.5 V and then to −0.4 V over the 120 days acclimation. Only weak current consumption and CH4 production were observed in the reactors without magnetite. But biocathodes were firmly developed and significant current consumption and CH4 production were recorded in the magnetite reactors. The robustness of electro-activity in the magnetite reactors was not affected with the elevation of cathode potentials from −0.6 V to −0.4 V. But, the current consumption and CH4 production were virtually halted in the reactors without magnetite when cathode potential was elevated to −0.4 V. Methanogens related to Methanospirillum were enriched on cathode surface of the magnetite reactors at −0.4 V, while Methanosarcina relatively dominated in the reactors without magnetite. Methanobacterium also increased in the magnetite reactors but stayed off electrodes in the culture medium at −0.4 V. Apparently, magnetite greatly facilitates the development of biocathodes, and it appears that with the aid of magnetite Methanospirillum spp. can adapt to high cathode potentials performing the efficient electromethanogenesis.IMPORTANCEConverting CO2 to CH4 through bioelectrochemistry is a promising approach for development of green energy biotechnology. This process however requires setting the low cathode potentials, which takes cost. In this study, we test if magnetite, a conductive iron mineral, can facilitate the adaption of methanogens to the elevation of cathode potentials. In the two-chamber reactors constructed using inoculants obtained from a paddy field soil, biocathodes were firmly developed in the presence of magnetite, whereas only weak electro-activity was observed in the reactors without magnetite. The elevation of cathode potentials did not affect the robustness of electro-activity in the magnetite reactors over the 120 days acclimation. Methanospirillum was identified as the key methanogens associated with cathode surface during the operation at relatively high potentials. The findings reported in this study shed a new light on the adaption of methanogen community to the elevated cathode potentials in the presence of magnetite.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Response of methanogen community to elevation of cathode potentials in the presence of magnetite

Gao

Wang

Huang

et al. 2020

Preprint

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“…However, carbon-based electrodes provide slow catalysis for cathodic HER, which seems to be critical for enriching hydrogenotrophic methanogens (Kim et al, 2017;Liu et al, 2016;Park et al, 2018d). Some previous studies successfully employed metal catalyst on carbon electrodes, such as nickel-and platinum-coated carbon materials, to provide superior HER (Kim et al, 2017;Liu et al, 2016;Park et al, 2018d), while these catalysts are still quite expensive.…”

Section: Introductionmentioning

confidence: 99%

“…However, carbon based-cathode materials, such as carbon fiber, carbon cloth, and carbon brush, have been employed in most of the previous studies due to their high surface area and biocompatibility properties (Choi et al, 2017; De Vrieze et al, 2014; Liu et al, 2016). However, carbon-based electrodes provide slow catalysis for cathodic HER, which seems to be critical for enriching hydrogenotrophic methanogens (Kim et al, 2017; Liu et al, 2016; Park et al, 2018d). Some previous studies successfully employed metal catalyst on carbon electrodes, such as nickel- and platinum-coated carbon materials, to provide superior HER (Kim et al, 2017; Liu et al, 2016; Park et al, 2018d), while these catalysts are still quite expensive.…”

Section: Introductionmentioning

confidence: 99%

Characterization and significance of extracellular polymeric substances, reactive oxygen species, and extracellular electron transfer in methanogenic biocathode

Zakaria

Dhar

2020

Preprint

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Carbon-based electrodes have been mostly used as a biocathode material in microbial electrolysis cell assisted anaerobic digestion (MEC-AD) due to their excellent biocompatibility and higher surface area over metal-based electrodes. Here, we report a multifaceted approach combining characterization of microbial communities, extracellular polymeric substances (EPS), redox oxygen species (ROS), and expression of genes associated with extracellular electron transfer (EET) to shed light on mechanisms governing electro-methanogenic activity in different biocathode materials. Carbon fiber and stainless-steel mesh biocathode were tested in MEC-AD systems fed with synthetic glucose medium. Despite the higher specific surface area provided by carbon fiber biocathode, methanogenesis performance was much inferior (100.3 mL CH4) than that obtained from a stainless steel biocathode (179.5 mL CH4). Interestingly, biofilms did not entirely cover the surfaces of carbon fibers, while stainless steel biocathode showed evenly denser biofilms with higher biovolume (30.2±4.2 vs. 13.5±2.8 μm3/μm2). Analyses of microbial communities indicated that the key mechanism for electro-methanogenesis in both reactors was hydrogenotrophic methanogenesis by Methanobacterium species. The redox activity of EPS derived from biocathode, as well as expressions of EET genes, suggested that electro-methanogenesis via direct electron transfer might have occurred to some extent in both biocathodes. Higher abundance of strictly hydrogenotrophic Methanobacterium sp. and homoacetogenic Acetobacterium appeared to play a major role in higher methanogenesis performance from stainless steel biocathode. It was possibly attributed to effective catalysis of hydrogen evolution reaction (HER) on stainless steel biocathode. The most considerable secretion of EPS accompanied by the lowest ROS level in stainless steel biocathode indicated that higher EPS possibly protected cells from harsh metabolic conditions (e.g., unfavorable local pH) induced by faster HER. The results of this study have important significance in the development of effective biocathode for MEC-AD systems.HighlightsStainless-steel mesh outperformed carbon fibers for methanogenic biocathode.Multifaceted characterization of biofilms unveiled underlying mechanisms.The results confirmed H2-utilizing methanogenesis is the dominant pathway.Homoacetogenesis only played a crucial role in the stainless-steel biocathode.Biocathode EPS might be responsible for superior methanogenesis.Graphical Abstract

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Preparation of Cobalt Nanoparticles

et al. 2021

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The development of modern chemistry is currently proceeding in several priority areas including investigations focused on the synthesis, stabilisation, and application of transition metal nanoparticles (NPs), which are widely used in physical, chemical, engineering, and biomedical processes. A special place among known transition metal NPs is occupied by cobalt nanoparticles, since they are used for highly important targets, such as creation of new catalysts, magnetic devices, composites, or carriers for drug delivery. The selective preparation of NPs is a difficult task that requires special conditions and has some limitations. In this minireview, we summarise the most successful and most efficient methods for obtaining Co NPs, including chemical and physical aspects of their preparation.

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Improvement in methanogenesis by incorporating transition metal nanoparticles and granular activated carbon composites in microbial electrolysis cells

Cited by 49 publications

References 32 publications

Response of methanogen community to elevation of cathode potentials in the presence of magnetite

Response of methanogen community to elevation of cathode potentials in the presence of magnetite

Characterization and significance of extracellular polymeric substances, reactive oxygen species, and extracellular electron transfer in methanogenic biocathode

Preparation of Cobalt Nanoparticles

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