Gas diffusion electrodes improve hydrogen gas mass transfer for a hydrogen oxidizing bioanode

Area of Science:

• Electrochemistry
• Environmental Science
• Biotechnology

Background:

• Bioelectrochemical systems (BESs) enable metal recovery via anode oxidation of substrates.
• Hydrogen gas has been explored as an electron donor for copper recovery in BESs.
• Mass transfer limitations of hydrogen to the bioanode hindered current production.

Purpose of the Study:

• To enhance hydrogen mass transfer to the bioanode in BESs.
• To investigate the effect of a gas diffusion electrode (GDE) on hydrogen oxidation.
• To explore the impact of bicarbonate addition on current generation.

Main Methods:

• Utilized a gas diffusion electrode (GDE) to improve hydrogen mass transfer.
• Introduced bicarbonate to the influent to facilitate acetate production.
• Optimized mass transfer through enhanced mixing and bicarbonate supplementation.

Main Results:

• GDE use increased hydrogen oxidation current density to 2.9 A m^-2.
• Bicarbonate addition (50 mmol L^-1) resulted in acetate production and increased current density to 10.7 A m^-2.
• Combined GDE, bicarbonate, and enhanced mixing achieved a current density of 17.1 A m^-2.

Conclusions:

• Hydrogen gas is a viable electron donor for bioanodes, with acetate as a potential intermediate.
• Optimized mass transfer and substrate addition are crucial for efficient BES performance.
• This approach offers potential for metal recovery in hydrogen-rich environments lacking organic matter.