Effects of applied potential and reactants to hydrogen-producing biocathode in a microbial electrolysis cell

Swee Su Lim, Byung Hong Kim, Li Da Li, Yujie Feng, Wan Ramli Wan Daud, Keith Scott, Eileen Hao Yu

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Understanding the mechanism of electron transfer between the cathode and microorganisms in cathode biofilms in microbial electrolysis cells (MECs) for hydrogen production is important. In this study, biocathodes of MECs were successfully re-enriched and subjected to different operating parameters: applied potential, sulfate use and inorganic carbon consumption. It was hypothesized that biocathode catalytic activity would be affected by the applied potentials that initiate electron transfer. While inorganic carbon, in the form of bicarbonate, could be a main carbon source for biocathode growth, sulfate could be a terminal electron acceptor and thus reduced to elemental sulfurs. It was found that potentials more negative than -0.8 V (vs. standard hydrogen electrode) were required for hydrogen production by the biocathode. In additional, a maximum hydrogen production was observed at sulfate and bicarbonate concentrations of 288 and 610 mg/L respectively. Organic carbons were found in the cathode effluents, suggesting that microbial interactions probably happen between acetogens and sulfate reducing bacteria (SRB). The hydrogen-producing biocathode was sulfate-dependent and hydrogen production could be inhibited by excessive sulfate because more energy was directed to reduce sulfate (E° SO42-/H2S = -0.35 V) than proton (E° H+/H2 = -0.41 V). This resulted in a restriction to the hydrogen production when sulfate concentration was high. Domestic wastewaters contain low amounts of organic compounds and sulfate would be a better medium to enrich and maintain a hydrogen-producing biocathode dominated by SRB. Besides the risks of limited mass transport and precipitation caused by low potential, methane contamination in the hydrogen-rich environment was inevitable in the biocathode after long term operation due to methanogenic activities.

Original languageEnglish
Article number318
JournalFrontiers in Chemistry
Volume6
Issue numberAUG
DOIs
Publication statusPublished - 1 Aug 2018

Fingerprint

Regenerative fuel cells
Sulfates
Hydrogen
Hydrogen production
Cathodes
Carbon
Bicarbonates
Electrons
Bacteria
Precipitation (meteorology)
Methane
Biofilms
Organic carbon
Organic compounds
Sulfur
Microorganisms
Protons
Effluents
Catalyst activity
Wastewater

Keywords

  • Bicarbonate conversion
  • Electron bifurcation
  • Hydrogen-producing biocathode
  • Microbial electrolysis cell
  • Sulfate reduction

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Effects of applied potential and reactants to hydrogen-producing biocathode in a microbial electrolysis cell. / Lim, Swee Su; Kim, Byung Hong; Da Li, Li; Feng, Yujie; Wan Daud, Wan Ramli; Scott, Keith; Yu, Eileen Hao.

In: Frontiers in Chemistry, Vol. 6, No. AUG, 318, 01.08.2018.

Research output: Contribution to journalArticle

Lim, Swee Su ; Kim, Byung Hong ; Da Li, Li ; Feng, Yujie ; Wan Daud, Wan Ramli ; Scott, Keith ; Yu, Eileen Hao. / Effects of applied potential and reactants to hydrogen-producing biocathode in a microbial electrolysis cell. In: Frontiers in Chemistry. 2018 ; Vol. 6, No. AUG.
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