Activated carbon-Fe catalyst modification on stainless steel cathode affects hydrogen production in microbial electrolysis cell

Abstract

Microbial Electrolysis Cell (MEC) can be used to produce hydrogen gas from organic matter contained in wastewater. However, at the cathode of MECs, hydrogen production may be limited by methanogenesis wherein CO2 and hydrogen protons react to form methane and water. In this study, activated carbon (AC)-Fe was used as a catalyst coated onto SS mesh 304 cathode. AC-Fe/SS was chosen for its high surface area, good activity, and stability. The combination of AC-Fe on SS was expected to increase hydrogen production in MECs. Adsorption and phase inversion were chosen to coat AC-Fe mixture on SS. The research was carried out in a 100 mL MEC reactor with an operating time of 258 h. The produced hydrogen was analyzed for its purity by GC-TCD. Voltage measurements were carried out using a digital multimeter. Additionally, bacterial growth was analyzed by spectrophotometer. The highest fraction of hydrogen gas production was 60% without catalyst (uncoated) over only 0.08% with AC-Fe/SS. The highest value of optical density for bacterial growth was 0.611 for AC-Fe/SS, higher than 0.427 without catalyst. The highest current density was 99.11 mA/m2 for AC-Fe/SS and 59.52 mA/m2 without catalyst. The results suggested AC-Fe/SS coating allows for increased bacterial growth and voltage generation at the cost of an adverse effect on hydrogen gas production.