Electricity generation in microbial fuel cell from wet torrefaction wastewater and locally developed corncob electrodes

Abstract

Corncob pyrochar activated with steam (CCA) and nonactivated corncob pyrochar (NCC) were produced and characterized. The performance of the best material was tested in a dual-chambered microbial fuel cell (MFC) as an electrode for bioelectricity generation using wet torrefaction wastewater as substrate. Pyrolysis of 80.3 g of dried corncobs was carried out at 600 • C under a constant N 2 flow of 3 L min −1 for 30 min and the resulting pyrochar was activated using steam also at 600 • C. Voltage and current outputs from the MFC were recorded daily for 18 days. The proximate and Brunauer-Emmett-Teller (BET) surface area analyses revealed that CCA had the highest fixed carbon content of 71.9 % and higher surface area of 104.0 m 2 g −1 respectively. A larger pore diameter of 1.9 × 10 −3 µm was also recorded with the CCA than 1.2 × 10 −3 µm for NCC. The MFC produced a maximum power output of 21.5 mW. The physicochemical analyses of the wastewater effluent revealed an increased electrical conductivity from 1724 to 3460 µS cm −1 with a significant decrease by 91.9% in the total organic carbon (TOC) from 3700 to 298 mg L −1 . Steam activation increases the surface area, porosity, stability and redox reversibility of the corncob pyrochar. Therefore, steam-activated corncob pyrochar performed well in MFCs due to the high power output observed. K E Y W O R D Sbiobased corncob pyrochar, electrodes in MFC, power output of MFC, steam activation, wastewater This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Pyrolysis of Corncobs to Produce Biobased Conductive Materials as Electrodes for Potential Application in Microbial Fuel Cells (MFCs)

“…The ECs of NAC, SAC and KAC were obtained as a function of the sample's Ohmic resistance using a specially improvised device and a multimeter as reported in the work of Celzard et al [22]. The conductivities of each sample were also recorded after adding various external metallic weights (10 kg, 5 kg, and 2 kg) to the sample also taking into consideration the weight of the lid (0.192 kg) in each case and the resulting pressure (p) was also estimated from the following equation in each case as also described by Musa et al [16]. The EC (Ϭ) and Bulk density (ϱ) of each of the pyrochar samples were determined using equations 2 and 3 respectively.…”

“…From the nitrogen adsorption/desorption data obtained, multipoint BET method was used to determine the SABET using the isotherms obtained at 77 K with liquid nitrogen [23,24]. As usual, sample degassing was performed at 180 °C under vacuum for 24 h before measurement [16].…”

“…Under a JSM-IT100 scanning electron microscope (SEM), the NAC, SAC, and KAC were examined microscopically. At a magnification of x1000, the pore diameters of all the pyrochar samples were examined and SEM photomicrographs were captured as described by Musa et al [16].…”

“…Interestingly, the main component of MFC is the use of appropriate electrodes, where microorganisms colonize and form biofilms [16]. There are several criteria for evaluating the suitability of bioelectrodes in microbial electrochemical systems and these includes surface roughness, biocompatibility, porosity, conductivity, and hydrophilicity [17].…”

Cascade Membrane System for Separation of Water and Organics from Liquid By-Products of HTC of the Agricultural Digestate—Evaluation of Performance

“…Overall, recirculation of the liquid by-products or its subsequent use for maximum energy recovery and increased systemic efficiency offers many opportunities [43]. Several studies report the composition of liquid HTC by-products [77][78][79], with many indicating potential synergies between HTC and anaerobic digestion (AD) [52,80,81] or application of the effluent in microbial fuel cells [82].…”