Electrodeposited Hybrid Biocathode-Based CO2 Reduction via Microbial Electro-Catalysis to Biofuels (original) (raw)
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In the direction of generating value added chemicals from carbon dioxide (CO 2) reduction through microbial electrosynthesis (MES), considering the crucial impact of the electrode material for the biofilm development and electron delivery, an attempt was made in this study to evaluate the efficiency of two different materials as biocathodes and their respective output in terms of electrosynthesis. The electrode material is a key component in the MES process. Several electrodes such as platinum, graphite foil, dimentionally stable anode (DSA) and graphite rod, and VITO-CoRE™ derived electrodes were tested for their suitability for ideal electrode combination in a three electrode cell setup. Bicarbonates (the dissolved form of CO 2) was reduced to acetate by a selectively developed biocathode under a mild applied cathodic potential of À400 mV (vs. SHE) in 500 mL of single chamber MES cells operating for more than four months. Among the two electrode combinations evaluated, VITO-CoRE™-PL (VC-IS, plastic inert support) as the cathode and VITO-CoRE™-SS (VC-SS, stainless steel metal support) as the counter electrode showed higher production (4127 mg L À1) with a volumetric production rate of 0.569 kg per m 3 per d than the graphite rod (1523 mg L À1) with a volumetric production rate of 0.206 kg per m 3 per d. Contrary to the production efficiencies, the coulombic efficiency was higher with the second electrode combination (40.43%) than the first electrode combination (29.91%). Carbon conversion efficiency to acetate was higher for VC-IS (90.6%) than the graphite rod (82.0%).
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Microbial electrocatalysis reckons on microbes as catalysts for reactions occurring at electrodes. Microbial fuel cells and microbial electrolysis cells are well-known in this context; both prefer the oxidation of organic and inorganic matter for producing electricity. Notably, the synthesis of high energy-density chemicals (fuels) or their precursors by microorganisms using bio-cathode to yield electrical energy is called Microbial Electrosynthesis (MES), giving an exceptionally appealing novel way for producing beneficial products from electricity and wastewater. This review accentuates the concept, importance and opportunities of MES, as an emerging discipline at the nexus of microbiology and electrochemistry. Production of organic compounds from MES is considered as an effective technique for the generation of various beneficial reduced end-products (like acetate and butyrate) as well as in reducing the load of CO2 from the atmosphere to mitigate the harmful effect of greenhouse...
Evaluation of biocathode materials for microbial electrosynthesis of methane and acetate
Bioelectrochemistry, 2022
This study compares carbon felt (CF), granular activated carbon (GAC), and a conductive acrylonitrile butadiene styrene (cABS) polymer cathodes for CH 4 and acetate production in a microbial electrosynthesis (MES) cell. At an applied voltage of 2.8 V and continuous CO 2 flow, the CF biocathode MES cell showed the highest CH 4 production rate of 1420 ± 225 mL V c-1 d-1 (V c = cathode volume), also producing acetate at a rate of 710 ± 110 mg V c-1 d-1. The acetate production increased and CH 4 production decreased when using the GAC cathode (720 ± 94 mL V c-1 d-1 and 236 ± 65 mg V c-1 d-1 , respectively). When the cABS cathode was used, the CH 4 production declined to 250 ± 35 mL V c-1 d-1 , while the acetate production increased to 1105 ± 130 mg V c-1 d-1. The biocatalytic activity of cABS increased after in-situ electrodeposition of Ni and Fe, resulting in a current increase from 205 mA to 380 mA accompanied by increasing acetate and ethanol production (1405 mg V c-1 d-1 and 240 mg V c-1 d-1 , respectively), while the CH 4 production decreased. The cABS cathode showed the highest specific (per surface area) activity for acetate and CH 4 production. © 20XX
Energies
Bioelectrochemical systems (BESs) is a term that encompasses a group of novel technologies able to interconvert electrical energy and chemical energy by means of a bioelectroactive biofilm. Microbial electrosynthesis (MES) systems, which branch off from BESs, are able to convert CO2 into valuable organic chemicals and fuels. This study demonstrates that CO2 reduction in MES systems can be enhanced by enriching the inoculum and improving CO2 availability to the biofilm. The proposed system is proven to be a repetitive, efficient, and selective way of consuming CO2 for the production of acetic acid, showing cathodic efficiencies of over 55% and CO2 conversions of over 80%. Continuous recirculation of the gas headspace through the catholyte allowed for a 44% improvement in performance, achieving CO2 fixation rates of 171 mL CO2 L−1·d−1, a maximum daily acetate production rate of 261 mg HAc·L−1·d−1, and a maximum acetate titer of 1957 mg·L−1. High-throughput sequencing revealed that CO2...
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Microbial electrosynthesis (MES) can sustainably convert CO2 to products and significant research is currently being conducted towards this end, mainly in laboratory-scale studies. The high-cost ion exchange membrane, however, is one of the main reasons hindering the industrialization of MES. This study investigates the conversion of CO2 (as a sole external carbon source) to CH4 using membraneless MES inoculated with anaerobic granular sludge. Three types of electrodes were tested: carbon cloth (CC) and CC functionalized with Cu NPs, where Cu NPs were deposited for 15 and 45 min, respectively. During the MES experiment, which lasted for 144 days (six cycles), methane was consistently higher in the serum bottles with CC electrodes and applied voltage. The highest CH4 (around 46%) was found in the second cycle after 16 days. The system’s performance declined during the following cycles; nevertheless, the CH4 composition was twice as high compared to the serum bottles without voltage. ...
Bioresource Technology Reports, 2019
This study demonstrates a novel approach for combined energy carrier production and energy storage in a Microbial Electrosynthesis System (MES). Continuous production of high purity methane (CH 4) from carbon dioxide (CO 2) was achieved in a 0.65 L carbon felt-filled cathode compartment of a membraneless MES. CH 4 production reached 0.72 L d −1 at an energy consumption of 26 Wh L CH4 −1. Owing to the membraneless design of the MES, pH control of the electrode compartments was not required, with the cathode compartment pH remaining below 8.5. Electrochemical characterization showed a progressive increase of the MES internal ca-pacitance from 2.1 F to 3.2 F. Bioelectrochemical conversion of CO 2 to CH 4 can be used for long-term energy storage (power-togas conversion) combined with CO 2 sequestration, while the internal capacitance of elec-troactive biofilms can be exploited to develop bioelectrochemical supercapacitors for fast energy return to the electrical grid.
Environmental Science & Technology Letters, 2015
Using carbon dioxide for bioproduction combines decreased greenhouse gas emissions with a decreased dependence on fossil carbon for production of multicarbon products. Microbial electrosynthesis (MES) enables this, using renewable energy to drive the reduction of CO 2 at the cathode of an electrochemical cell. To date, low product concentrations preclude cost-effective extraction during MES. Here we present an approach that couples production and recovery of acetate in a single, three-chamber reactor system. Acetate was produced at 61% Coulombic efficiency and fully recovered as an acidified stream containing up to 13.5 g L −1 (225 mM) acetic acid, the highest obtained thus far. In contrast to previous MES studies, a single separated acidic product was generated through in situ membrane electrolysis enabling further upgrading.
Biotechnology Advances, 2021
Decarbonisation of the economy has become a priority at the global level, and the resulting legislative pressure is pushing the chemical and energy industries away from fossil fuels. Microbial electrosynthesis (MES) has emerged as a promising technology to promote this transition, which will further benefit from the decreasing cost of renewable energy. However, several technological challenges need to be addressed before the MES technology can reach its maturity. The aim of this review is to critically discuss the bottlenecks hampering the industrial adoption of MES, considering the whole production process (from the CO 2 source to the marketable products), and indicate future directions. A flexible stack design, with flat or tubular MES modules and direct CO 2 supply, is required for site-specific decentralised applications. The experience gained for scaling-up electrochemical cells (e.g. electrolysers) can serve as a guideline for realising pilot MES stacks to be technologically and economically evaluated in industrially relevant conditions. Maximising CO 2 abatement rate by targeting high-rate production of acetate can promote adoption of MES technology in the short term. However, the development of a replicable and robust strategy for production and in-line extraction of higher-value products (e.g. caproic acid and hexanol) at the cathode, and meaningful exploitation of the currently overlooked anodic reactions, can further boost MES cost-effectiveness. Furthermore, the use of energy storage and smart electronics can alleviate the fluctuations of renewable energy supply. Despite the unresolved challenges, the flexible MES technology can be applied to decarbonise flue gas from different sources, to upgrade industrial and wastewater treatment plants, and to produce a wide array of green and sustainable chemicals. The combination of these benefits can support the industrial adoption of MES over competing technologies. European Union (EU) set a target of 20% GHG reduction by 2020, 40% by 2030 and of achieving a net-zero carbon economy by 2050. The legislative pressure of EU on carbon emissions allowed to achieve the 2020 target already in 2017, when a total of 4483 Mt CO 2 eq were produced, 22% lower than the emissions in 1990 (European Environment Agency, 2019). However, EU economy remains largely dependent on fossil fuels, which currently account for 65% of the energy supply and