Department of Civil and Environmental Engineering, Penn State University, 231Q Sackett Building, University Park, PA 16802, United States; Environmental Research Group, Research Institute of Industrial Science and Technology (RIST), 67 Cheongam-ro, Nam-gu, Pohang-si, Gyeongsangbuk-do, 37673 Republic of Korea.
Department of Civil and Environmental Engineering, Penn State University, 231Q Sackett Building, University Park, PA 16802, United States.
Water Res. 2022 Jul 1;219:118597. doi: 10.1016/j.watres.2022.118597. Epub 2022 May 13.
Microbial electrosynthesis (MES) cells use renewable energy to convert carbon dioxide into valuable chemical products such as methane and acetate, but chemical production rates are low and pH changes can adversely impact biocathodes. To overcome these limitations, an MES reactor was designed with a zero-gap electrode configuration with a cation exchange membrane (CEM) to achieve a low internal resistance, and a vapor-fed electrode to minimize pH changes. Liquid catholyte was pumped through a carbon felt cathode inoculated with anaerobic digester sludge, with humidified N gas flowing over the abiotic anode (Ti or C with a Pt catalyst) to drive water splitting. The ohmic resistance was 2.4 ± 0.5 mΩ m, substantially lower than previous bioelectrochemical systems (20-25 mΩ m), and the catholyte pH remained near-neutral (6.6-7.2). The MES produced a high methane production rate of 2.9 ± 1.2 L/L-d (748 mmol/m-d, 17.4 A/m; Ti/Pt anode) at a relatively low applied voltage of 3.1 V. In addition, acetate was produced at a rate of 940 ± 250 mmol/m-d with 180 ± 30 mmol/m-d for propionate. The biocathode microbial community was dominated by the methanogens of the genus Methanobrevibacter, and the acetogen of the genus Clostridium sensu stricto 1. These results demonstrate the utility of this zero-gap cell and vapor-fed anode design for increasing rates of methane and chemical production in MES.
微生物电合成 (MES) 细胞利用可再生能源将二氧化碳转化为有价值的化学产品，如甲烷和乙酸盐，但化学产物的生成率较低，pH 值的变化也会对生物阴极产生不利影响。为了克服这些限制，设计了一种具有零间隙电极配置的 MES 反应器，采用阳离子交换膜 (CEM) 以实现低内阻，并采用蒸气进料电极将 pH 值的变化最小化。液态阴极电解液通过接种了厌氧消化污泥的碳纤维毡阴极泵送，湿润的 N 气体流过非生物阳极（涂有 Pt 催化剂的 Ti 或 C）以驱动水分解。欧姆电阻为 2.4 ± 0.5 mΩ m，明显低于以前的生物电化学系统（20-25 mΩ m），并且阴极电解液的 pH 值保持在接近中性（6.6-7.2）。MES 在相对较低的 3.1 V 施加电压下产生了 2.9 ± 1.2 L/L-d（748 mmol/m-d，17.4 A/m；Ti/Pt 阳极）的高甲烷生成速率。此外，以 940 ± 250 mmol/m-d 的速率产生了乙酸盐，以 180 ± 30 mmol/m-d 的速率产生了丙酸盐。生物阴极微生物群落主要由产甲烷菌属 Methanobrevibacter 和严格意义上的梭菌属 Clostridium sensu stricto 1 的产乙酸菌组成。这些结果表明，这种零间隙电池和蒸气进料阳极设计对于提高 MES 中甲烷和化学产物的生成率是有用的。
