The effect of the polarised cathode, formate and ethanol on chain elongation of acetate in microbial electrosynthesis
The effect of the polarised cathode, formate and ethanol on chain elongation of acetate in microbial electrosynthesis
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DOI：
10.1016/j.apenergy.2020.116310
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发表时间：
2021-01-18
期刊：
影响因子：
11.2
通讯作者：
Yu, Eileen H.
中科院分区：
文献类型：
--
作者：
Izadi, Paniz;Fontmorin, Jean-Marie;Yu, Eileen H.
在微生物电合成中，CO2还原为乙酸盐已被广泛研究。然而，较长链化学品和生物燃料的选择性和定量生产仍然是一个瓶颈。在生物电化学系统中，在链延伸期间仅由阴极电极提供的足够能量的缺乏是关键挑战之一。据推测，需要比极化阴极额外的电子供体来引导生产朝向比乙酸酯更长链的羧酸酯。在该研究中，除了阴极相对于Ag/AgCl保持在-1.0 V之外，甲酸盐和乙醇在由CO2进料的反应器中单独供应45天，以研究它们对生产的影响。虽然乙酸盐仍然是主要产物，但提供电子供体将生产导向比仅存在极化阴极的情况下更多样化和更长链的有机化学品。在供应甲酸盐后观察到丁酸盐（最大浓度增加3.8倍）和丁醇（最大6.8 +/- 0.3 mmol C L-1）的生产的显著改善，而乙醇增加了产物的多样性。在开路电位下在反应器中供应甲酸盐和乙醇另外30天澄清了在不存在极化阴极的情况下，只有乙醇可以为从乙酸盐生产丁酸盐提供足够的能量，其达到19.1 +/-2.3mmol C L-1的最高丁酸盐浓度。甲酸盐仅在极化阴极存在下消耗。在我们的研究中提出，在仅阴极电极或阴极电极和甲酸盐存在下的C4产物的产生可以与乙酸盐初始还原为乙醇相关联，所述乙醇用于通过乙酸盐产生C4产物。在两个反应器中检测到痕量水平的己酸盐和己醇，所述反应器仅在极化阴极的存在下供应甲酸盐和乙醇。
Reduction of CO2 to acetate in microbial electrosynthesis has been widely studied. However, the selective and quantitative production of longer chain chemicals and biofuels is still a bottleneck. Lack of sufficient energy provided by only the cathode electrode in Bio-electrochemical systems during chain elongation is one of the key challenges. It is assumed that additional electron donors than a polarised cathode is required to steer the production towards longer chain of carboxylates than acetate. In this study, formate and ethanol were supplied separately in the reactors fed by CO2 for 45 days in addition to the cathodes poised at -1.0 V vs. Ag/AgCl to investigate their effect on production. Although acetate was still the major product, supplying electron donors directed the production towards more diverse and longer chain organic chemicals than that in presence of the polarised cathode only. Significant improvement in the production of butyrate (x3.8 increase in maximum concentration) and butanol (maximum of 6.8 +/- 0.3 mmol C L-1) was observed after supplying formate, while ethanol increased the diversity of the products. Supplying formate and ethanol in reactors for another 30 days under open circuit potential clarified that only ethanol could provide sufficient energy for butyrate production from acetate in the absence of polarised cathode, which reached the highest butyrate concentration of 19.1 +/- 2.3 mmol C L-1. Formate was only consumed in presence of polarised cathode. It is proposed in our study that production of C4 products in presence of only cathodic electrode or cathodic electrode and formate could be associated to initial reduction of acetate to ethanol, consumed for production of C4 products through acetate. Trace levels of caproate and hexanol were detected in both reactors supplied with formate and ethanol only in the presence of polarised cathode.