Sustainable Syntheses and Sources of Nanomaterials for Microbial Fuel/Electrolysis Cell Applications: An Overview of Recent Progress

Abstract

The use of microbial fuel cells (MFCs) is quickly spreading in the fields of bioenergy generation and wastewater treatment, as well as in the biosynthesis of valuable compounds for microbial electrolysis cells (MECs). MFCs and MECs have not been able to penetrate the market as economic feasibility is lost when their performances are boosted by nanomaterials. The nanoparticles used to realize or decorate the components (electrodes or the membrane) have expensive processing, purification, and raw resource costs. In recent decades, many studies have approached the problem of finding green synthesis routes and cheap sources for the most common nanoparticles employed in MFCs and MECs. These nanoparticles are essentially made of carbon, noble metals, and non-noble metals, together with a few other few doping elements. In this review, the most recent findings regarding the sustainable preparation of nanoparticles, in terms of syntheses and sources, are collected, commented, and proposed for applications in MFC and MEC devices. The use of naturally occurring, recycled, and alternative raw materials for nanoparticle synthesis is showcased in detail here. Several examples of how these naturally derived or sustainable nanoparticles have been employed in microbial devices are also examined. The results demonstrate that this approach is valuable and could represent a solid alternative to the expensive use of commercial nanoparticles.

Engineered nanomaterials in microbial fuel cells – Recent developments, sustainability aspects, and future outlook

“…Considering that the membranes and electrodes account for over 80% of the total MFC costs, a considerable reduction up to 30-40% can make these technologies more competitive to other (waste)water treatment methods. Utilization of inexpensive raw materials (including recycled or naturally occurring materials) as well as the development of facile and cost-effective methods can be considered a potential approach to reduce the costs of MFC fabrication [189]. For instance, Feng et al [190] concluded that among the high-performance materials, SS electrodes (SUS 304) are the cheapest option (21 k$/m 3 ), followed by titanium plate and graphite felt (30 k$/m 3 , and 25-75 k$/m 3 , respectively).…”

Recent Application of Nanomaterials to Overcome Technological Challenges of Microbial Electrolysis Cells

“…The development of nanomaterials has often provided a breakthrough to overcome technological issues in diverse engineering fields because nanomaterials have various distinctive and outstanding properties that are not present in macro-or bulk-sized counterparts. Owing to their preferred properties, such as high electrical conductivity, high specific surface area, high durability, high cost-effectiveness, good catalytic capability for hydrogen evolution, and anti-microbial activity, various nanomaterials have been developed and applied to mitigate some of the aforementioned challenges of MECs by improving the characteristics and performance of critical components (i.e., anode/cathode electrodes, catalysts, and separators) or substituting high-cost components, as shown in Figure 3 [12,25]. To synthesize nanomaterials applied for MECs, various approaches for nanomaterials, such as thermal annealing, electrochemical anodization, and electrodeposition, have been reported, as summarized in Table 1.…”

Synthesis of Plant‐Derived Khat Waste for Environmental Application

“…The pan and sample are heated, and the weight is measured with the heating rate cycle. The weight loss was recorded and analyzed [26,35]. Thermogravimetric analysis is used to know the thermal stability of materials by withstanding temperature as it continues to increase with time as mass is recorded and by this mass loss to find the moisture content, volatile, ash, and moisture contents of the given sample…”