Performance of iron – doped activated carbon synthesised from cocoa husk as a cathode catalyst in microbial fuel cell powered Fenton process

Abstract

Abstract BACKGROUND Bio‐electro‐Fenton (BEF) systems, specifically microbial fuel cell (MFC) driven electro‐Fenton (EF) systems, have gained significant attention in wastewater treatment in recent years. The role of the cathode catalyst in BEF is crucial, as it undergoes O 2 reduction via a 2e − oxygen reduction reaction (ORR) to produce H 2 O 2 . In this study, we have harnessed the abundant lignocellulosic composition of cocoa pod husk (CPH) to prepare a novel iron‐doped heterogeneous Fenton catalyst for the BEF system. Cocoa is typically grown for its wet beans, which constitute only one third of cocoa fruit by weight, while CPH makes up about two‐thirds of the weight and is often discarded as by‐product or waste. As a result, approximately 10 million tons of CPH are produced globally each year, highlighting the potential for transforming it into a value‐added product. To date, CPH has been utilised as a natural fertiliser, soil amendment, biomass fuel, poultry and livestock feed ingredient, and more. RESULTS The presence of mesoporous structure, iron content, oxygen containing functional groups, and prominent reduction peaks in cyclic voltammetry validated the Fe‐doped cocoa husk biochar's (Fe‐CHB) potential to act as an ORR catalyst. The BEF system achieved an open circuit voltage, current, and power densities of 0.697 V, 0.15 A/m 2 , and 0.040 W/m 2 , respectively, at an optimum resistance of 350 Ω. Optimisation of the process parameters using RSM and ANN predicted maximum dye removal efficiencies of 93.34% and 92.45%, respectively, at dye and substrate concentrations of 10 mg/L and 1 g/L. These predictions closely aligned with the experimental findings of 92.5%. CONCLUSION The synthesised catalyst provided large surface area, electrical conductivity, superior ORR catalytic efficiencies, and ample sites for H 2 O 2 activation. Hence, Fe‐CHB can serve as a highly effective electrocatalyst in BEF systems. © 2024 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Key findings

• ▸Iron-doped activated carbon from cocoa husk shows promising catalytic activity in the Fenton process
• ▸The material's high surface area and iron content contribute to its enhanced catalytic performance
• ▸The use of this catalyst in a microbial fuel cell-powered Fenton process achieves efficient wastewater treatment

Keywords

Identifiers

DOI

10.1002/jctb.7697

Journal

Journal of Chemical Technology & Biotechnology

Year

2024