ABSTRACT
Microbial desalination cells (MDCs) are considered as a sustainable technology for water desalination, wastewater treatment, and power generation. However, this neoteric technology suffers from different challenges, including sluggish oxygen reduction reaction and poor electron transfer from microbes to electrodes, ultimately leading to less power generation and desalination efficiency. This review delves into the intricate roles of both abiotic and biocatalysts in enhancing performance of MDCs through ion removal and charge transfer mechanisms. Detailed discussions highlight the comparative advantages and limitations of different catalyst types and insights into electrode modifications to optimise catalytic activity and biofilm formation. Further, recent advancements in electrode engineering, including surface coatings and integration of nanomaterial, geared towards enhancing efficiency of MDC and performance stability are discussed. Finally, future recommendations are provided, focusing on innovative catalyst designs, material integration, and considerations for scale-up and commercialisation, thereby offering a comprehensive roadmap for the continued advancement of MDC.
ABSTRACT
Microbial fuel cells (MFCs) have been the prime focus of research in recent years because of their distinctive feature of concomitantly treating and producing electricity from wastewater. Nevertheless, the electrical performance of MFCs is hindered by a protracted oxygen reduction reaction (ORR), and often a catalyst is required to boost the cathodic reactions. Conventional transition metals-based catalysts are expensive and infeasible for field-scale usage. In this regard, carbon-based electrocatalysts like waste-derived biochar and graphene are used to enhance the commercialisation prospects of MFC technology. These carbon-catalysts possess unique properties like superior electrocatalytic activity, higher surface area, and high porosity conducive to ORR. Theoretically, graphene-based cathode catalysts yield superior results than a biochar-derived catalyst, though at a higher cost. In contrast, the synthesis of waste-extracted biochar is economical; however, its ability to catalyse ORR is debatable. Therefore, this review aims to make a side-by-side techno-economic assessment of biochar and graphene-based cathode catalyst used in MFC to predict the relative performance and typical cost of power recovery. Additionally, the life cycle analysis of the graphene and biochar-based materials has been briefly discussed to comprehend the associated environmental impacts and overall sustainability of these carbo-catalysts.
