초록
<P><B>Abstract</B></P> <P>Impact of gas diffusion electrodes (GDEs) was evaluated in enhancing the CO<SUB>2</SUB> bio-availability for its transformation to C4-organics, especially to alcohols using selective mixed culture. Observed current density was more stable (9–11 A/m<SUP>2</SUP>) than submerged experiments reported and significantly varied with pH and respective CO<SUB>2</SUB> solubility. Uncontrolled operating pH (starting with 8.0) showed its impact on shifting/triggering alternate metabolic pathways to increase the carbon length (butyric acid) as well as producing more reduced end products, i.e. alcohols. During the experiments, CO<SUB>2</SUB> was transformed initially to a mixture of volatile fatty acids dominated with formic and acetic acids, and upon their accumulation, ethanol and butanol production was triggered. Overall, 21 g/l of alcohols and 13 g/l of organic acids were accumulated in 90 days with a coulombic efficiency (CE) of 49%. Ethanol and butanol occupied respectively about 45% and 16% of total products, indicating larger potential of this technology.</P> <P><B>Highlights</B></P> <P> <UL> <LI> C4-organics produced from carbon dioxide through electro-biocatalysis. </LI> <LI> Solubility and bio-availability of carbon dioxide increased with gas diffusion electrode. </LI> <LI> Uncontrolled pH triggered alternate metabolic pathways towards butyric acid and alcohols. </LI> <LI> 34 g/l of total products were accumulated in 90 days with coulumbic efficiency of 49%. </LI> <LI> Ethanol and butanol occupied about 45% and 16% of total products, respectively. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>