Marzorati S., Magni M., Campisi S., Ghiara G., Valtorta G.A., Gervasini A., Trasatti S.P., 2024, Development of Biochar-based Composites Electrodes from Pyrolysis of Coffee Silverskin: Microbial Fuel Cells for Wastewater Treatment, Chemical Engineering Transactions, 109, 7-12 DOI:10.3303/CET24109002

A recent study explores the innovative use of biochar-based composites as electrodes in microbial fuel cells (MFCs) for wastewater treatment. By implementing circular economy principles, researchers have developed cost-effective and eco-friendly materials from coffee silverskin, a byproduct of coffee roasting.

Coffee silverskin was subjected to pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More at 900°C to produce conductive biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More. This biochar was then utilized to create inks that formed microporous layers on carbon cloth, which served as cathodes in MFCs. The study also incorporated hydroxyapatite (HAP) into biochar to enhance the composite’s ability to remove inorganic pollutants like cadmium and zinc, while also treating organic pollutants.

MFCs operate by using bacteria found in wastewater to catalyze electrochemical reactions at the electrodes. This process reduces the Chemical Oxygen Demand (COD) of the wastewater and generates microcurrents. The study’s findings show that the biochar-based cathodes, particularly those combined with HAP, performed better than traditional materials, highlighting their potential for broader applications in pollutant removal.

Experiments demonstrated that the biochar-based MFCs achieved high COD removal efficiencies and generated more power compared to control MFCs using commercial activated carbonActivated carbon is a form of carbon that has been processed to create a vast network of tiny pores, increasing its surface area significantly. This extensive surface area makes activated carbon exceptionally effective at trapping and holding impurities, like a molecular sponge. It is commonly More. Additionally, the HAP/biochar composites exhibited significant sorption capacities for heavy metals, suggesting their effectiveness in treating wastewater contaminated with both organic and inorganic pollutants.

This research underscores the potential of biochar-based materials in developing sustainable and efficient wastewater treatment technologies, addressing the dual challenges of environmental remediation and clean energy generation. The innovative approach not only promotes waste valorization but also paves the way for the future design of smarter bioelectrochemical systems.