ABSTRACT
The current study investigated the development and application of lithium (Li)-doped zinc oxide (ZnO)-impregnated polyvinyl alcohol (PVA) proton exchange membrane separator in a single chambered microbial fuel cell (MFC). Physiochemical analysis was performed via FT-IR, XRD, TEM, and AC impedance analysis to characterize thus synthesized Li-doped ZnO. PVA-ZnO-Li with 2.0% Li incorporation showed higher power generation in MFC. Using coulombic efficiency and current density, the impact of oxygen crossing on the membrane cathode assembly (MCA) area was evaluated. Different amounts of Li were incorporated into the membrane to optimize its electrochemical behavior and to increase proton conductivity while reducing biofouling. When acetate wastewater was treated in MFC using a PVA-ZnO-Li-based MCA, the maximum power density of 6.3 W/m3 was achieved. These observations strongly support our hypothesis that PVA-ZnO-Li can be an efficient and affordable separator for MFC.
ABSTRACT
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 15-100â nm pores. EDS analysis of the FTWA-C showed the presence of hygroscopic oxides, mainly SO42- and SiO2. A slight peak observed at P/Poâ¼1, confirmed the presence of macropores. The FTWA-C separator showed proton transfer coefficient as high as 18.7 × 10-5â cm/s, and oxygen mass transfer coefficient of 2.1 × 10-4â cm/s. The FTWA-C displayed the highest operating voltage of 612.4.2â mV, the power density of 1.81â 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.
Subject(s)
Bioelectric Energy Sources , Clay , Protons , Silicon Dioxide , Electrodes , Oxygen , ElectricityABSTRACT
A bioelectrochemical reactor is an assembly, which facilitates energy generation and resource recovery using electrochemically active microorganisms. To maximise energy production from wastewater in this bioreactor system special design is required. Therefore, in the present study, continuous flow auto dripping bioelectrochemical reactors (AutoDriBERs) were developed as a single and multi-electrode assembly for urine treatment. Further, their performance was assessed by connecting reactors in series and parallel arrangements. AutoDriBER configured in series connection showed the highest 93.64 ± 1.57% chemical oxygen demand removal rate with the 1.38 ± 0.64â V voltage and 2.54â Wâ m-3 polarisation power density. The optimum flow rate for maximum voltage production was tested with various models i.e. the linear, exponential, Sweibull-1, and Sweibull-2 models to confirm voltage prediction and its validity. The Linear and exponential models were found best fitted for voltage production with R2 value of 0.999. These findings infer a novel approach toward optimisation of the complex, inexpensive and self-sufficient design for electricity generation from energy-rich urine wastewater in rural areas.
