Constructing an in-situ Fenton reaction using iron-air fuel cells with a graphite cathode for landfill leachate treatment

Abstract

The cost-effective removal of chemical oxygen demand (COD) and ammonia nitrogen (NH₄⁺-N) from landfill leachate remains a significant challenge. In this study, a Fenton reaction was established using an iron-air fuel cell (IAFC), examining H₂O₂ yields with three types of air cathodes and two types of electrolytes. The removal performance and mechanisms of landfill leachate by the IAFC were also analyzed. The results demonstrated that the graphite (GR) cathode generated more H₂O₂ than the activated carbon (AC) or platinum-carbon black (PCB) cathodes. The GR cathode exhibited greater effectiveness in a 10 g/L Na₂SO₄ electrolyte. A 20 g/L NaCl electrolyte can efficiently enhance the power output of the IAFC. However, excessive Cl^– may react with Fe²⁺, inhibiting the Fenton reaction and leading to H₂O₂ accumulation. The IAFC achieved removal rates of 58% for COD and 19% for NH₄⁺-N in landfill leachate. Among these, 35% of COD was removed by adsorption, and 17% of NH₄⁺-N was removed by Fenton oxidation. Through Raman analysis, FeOOH and Fe₂O₃ formed in the reactor environment were identified as adsorbents for common pollutants in landfill leachate. Constructing a Fenton reaction using an IAFC not only effectively treats landfill leachate but also recovers electrical energy, aligning with principles of green and sustainable development.

Graphical abstract

Keywords

Fuel cell / Landfill leachate / Electro-Fenton / Adsorption / Power output

Highlight

	● An iron-air fuel cell constructs a Fenton reaction for leachate treatment.
	● A graphite cathode with 10 g/L Na2SO4 produces Fenton reagent and electricity.
	● The system removes 58% of the COD and 19% of the NH4+-N from landfill leachate.
	● Raman and XRD confirmed the adsorbed products as FeOOH and Fe2O3.

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