Strategic development and performance evaluation of functionalized tea waste ash-clay composite as low-cost, high-performance separator in microbial fuel cell.

The separator is an important component of the microbial fuel cells (MFCs), which separates anode and cathode entities and facilitates ion transfer between both. Despite the high research in separators in recent years, the need for cost-effective, waste-driven selective separators in MFCs persists. Present study discloses the strategic fabrication of functionalized-tea-waste-ash-clay (FTWA-C) composite separator by integrating functionalized tea waste ash (FTWA) with potter's clay. Clay was used as a base, while FTWA was used as cation exchanger. FTWA and clay were separately mixed in four different ratios, 00:100 (C1); 05:95 (C2); 10:90 (C3); 15:85 (C4). Mixtures were then crafted manually as consecutive four layers. C1-side faced anode while separator-cathode-assembly was developed at C4. The separator was characterized by evaluating proton and oxygen transfer coefficient, and water-uptake analysis. The separator was also analysed for elemental composition, microstructure, particle size, and surface area and porous structure. SEM analysis of FTWA showed the presence of 15-100 nm pores. EDS analysis of the FTWA-C showed the presence of hygroscopic oxides, mainly SO42- and SiO2. A slight peak observed at P/Po∼1, confirmed the presence of macropores. The FTWA-C separator showed proton transfer coefficient as high as 18.7 × 10-5 cm/s, and oxygen mass transfer coefficient of 2.1 × 10-4 cm/s. The FTWA-C displayed the highest operating voltage of 612.4.2 mV, the power density of 1.81 W/m3, and COD removal efficiency of 87.52%. The fabrication cost of this separator was estimated to be $9.8/m2. FTWA-C could be an affordable and high-efficiency alternative for expensive ion-exchange membranes in MFCs.

Assessment of expanded polystyrene as a separator in microbial fuel cell.

Separators are considered as an important component in microbial fuel cells (MFCs) to facilitate ion transport and to prevent electrode short circuiting. In the present study, expanded polystyrene (EPS) was evaluated for the first time as a separator in a single-chamber air cathode and dual chamber aqueous cathode MFCs. The characteristics and performance of EPS were analyzed and compared with other conventionally used separators used in MFCs and was found to be competitive. Initially, the EPS was less impermeable to protons, resulting in delayed process startup (17 days) and stabilization (57 days), but gradually exhibited improved and stable performance. In the air cathode MFC with the EPS as the separator and domestic wastewater as the substrate, power production was 391 mW/m2, while power output of the aqueous cathode MFC was 328 mW/m2. The characteristics and cost analysis of EPS indicate that it can be a potential candidate as a separator in scaled-up MFC applications.