Exploring hydrogen production and distillery wastewater treatment using MnFe₂O₄·GGO nanocomposites in microbial...

Amid increasing economic and environmental challenges, integrating wastewater treatment with resource recovery has emerged as a critical strategy to enhance water security and sustainability. In this context, hydrogen production through microbial electrolysis cell (MEC) offers a promising pathway for clean and sustainable energy generation. The management of distillery effluent presents a significant environmental concern, primarily due to its detrimental effects on water quality. This study investigates a manganese ferrite/green graphene oxide nanocomposite as a cathode catalyst for enhancing hydrogen production in MECs. The nanocomposite was synthesized using eco-friendly methods, ensuring minimal environmental impact. Characterization studies were performed for the synthesized nanocomposite cathode, and the performance was evaluated in terms of hydrogen production rate (HPR) and cathodic hydrogen recovery. The results demonstrated that the nanocomposite significantly supports the hydrogen evolution reaction (HER). The optimal configuration of the nanocomposite yielded an HPR of 1.98 ± 0.2 mmol L^-1 D^-1, which is two-fold higher than that obtained using the control (0.938 ± 0.02 mmol L^-1 D^-1). Additionally, the stability of the nanocomposite was confirmed through electrochemical studies. The nanocomposite cathode caused a reduction in chemical oxygen demand (COD) in the wastewater by 48 ± 0.5%. The MnFe₂O₄/GO cathode exhibited a CHR of 60% ± 0.6%, with current generation of 28 A m^-2, indicating improved electron transfer efficiency. Electrochemical impedance analysis revealed a lower Warburg resistance of 4.531 kΩ for the nanocomposite, confirming enhanced ion diffusion and mass transfer characteristics, which directly boosted the overall electrochemical performance. In addition, the nanocomposite showed excellent electrochemical stability during long-term operation.