Efficient reduction of antimony by sulfate-reducer enriched bio-cathode with hydrogen production in a microbial electrolysis cell

Bio-cathodeMicrobial electrolysis cell (MEC) is a promising and eco-friendly technology for concurrent hydrogen production and heavymetal reduction. However, the bioreduction of Antimony (Sb) in a bio-electrochemical systemwith H2 production is not explored. In this study, two efficient sulfate-reducing bacterial (SRB) strains were used to investigate the enhanced bioreduction of sulfate and Sbwith H-2 production in theMEC. SRB Bio-cathode MECwas developed fromthe microbial fuel cell (MFC) and operatedwith an applied voltage of 0.8 V. The performance of the SRB bio-cathode was confirmed by cyclic voltammetry, linear sweep voltammetry and electrochemical impedance spectroscopy. SRB strains of BY7 and SR10 supported the synergy reduction of sulfate and Sb by sulfide metal precipitation reaction. Hydrogen gas was the main product of SRB bio-cathode, with 86.9%, and 83.6% of H-2 is produced by SR10 and BY7, respectively. Sb removal efficiency reached up to 88.2% in BY7 and 96.3% in SR10 with a sulfate reduction rate of 92.3 +/- 2.6 and 98.4 +/- 1.6 gm(-3)d(-1) in BY7 and SR10, respectively. The conversion efficiency of Sb (V) to Sb (III) reached up to 70.1% in BY7 and 89.2% in SR10. It was concluded that the total removal efficiency of Sb relies on the amount of sulfide concentration produced by the sulfate reduction reaction. The hydrogen production rate was increased up to 1.25 +/- 0.06 (BY7) and 1.36 +/- 0.02 m(3) H-2/(m(3.)d) (SR10) before addition of Sb and produced up to 0.893 +/- 0.03 and 0.981 +/- 0.02 m(3)H(2)/(m(3.)d) after addition of Sb. The precipitates were characterized by X-ray diffraction and X-ray photoelectron spectroscopy, which confirmed Sb (V) was reduced to Sb2S3. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study successfully enhanced the bioreduction of sulfate and antimony by utilizing two efficient sulfate-reducing bacterial strains in a SRB bio-cathode microbial electrolysis cell. The sulfate reduction products improved the reduction efficiency of Sb (V) and increased the hydrogen production.