A Membrane Reactor with Microchannels for Carbon Dioxide Reduction in Extraterrestrial Space

Long-term continuous oxygen supply is of vital importance during the process of space exploration. Considering the cost and feasibility, in situ resource utilization (ISRU) may be a promising solution. The conversion of CO2 to O2 is a key point for ISRU. In addition, the utilization of the abundant CO2 resources in the atmosphere of Mars is an important topic in the field of manned deep space exploration. The Sabatier reaction, Bosch reaction, and solid oxide electrolysis (SOE) are well-known techniques for the reduction of CO2. However, all the above techniques need great energy consumption. In this article, we designed an electrochemical membrane reactor at room temperature based on microfluidic control for the reduction of CO2 in extraterrestrial space. In this system, H2O was oxidized to O2 on the anode, while CO2 was reduced to C2H4 on the cathode. The highest Faraday efficiency (FE) for C2H4 was 72.7%, with a single-pass carbon efficiency toward C2H4 (SPCE-C2H4) of 4.64%. In addition, a microfluidic control technique was adopted to overcome the influence of the microgravity environment. The study may provide a solution for the long-term continuous oxygen supply during the process of space exploration.

Review on antibiotics treatment by electrochemical membrane reactor

Lower consumption, higher efficiency, environmental protection, and reliability are the development trends for the treatment of antibiotic wastewater in future. To accomplish this, the electrochemical membrane reactor (ECMR) is developed by combining membrane filtration and electrochemical advanced oxidation technology. The device configuration and working mode of the electrochemical membrane reactor are introduced and compared. Besides, the principles of the removal of antibiotics by the reactor are explained with emphasis. Furthermore, the commonly used cathode and anode materials of the reactor in the current research are summarized, and the electrode materials are discussed. The effects of selection and modification on the elimination of antibiotics in the reactor and the impact are analysed. To address the limitations of electrochemical membrane reactors, this review proposes that more research should be done in the aspects of antibiotic degradation mechanism, reduction of membrane electrode R&D costs, and actual application of amplification devices.

Beyond the catalyst: how electrode and reactor design determine the product spectrum during electrochemical CO2 reduction

As a remedy to the increasing concentration of greenhouse gases and depleting fossil resources, the electrochemical CO2 reduction closes the carbon cycle and provides an alternative carbon feedstock to the chemical and energy industry. While most contemporary research focuses on the catalyst activity, we emphasize the importance of the reactor design for an energetic efficient (EE) conversion. A design strategy for an electrochemical membrane reactor reducing CO2 to hydrogen, carbon monoxide (CO) and ethylene (C2H4) is developed. We present the stepwise development from an H-cell like setup using full-metal electrodes to a cell with gas diffusion electrodes (GDE) towards high current efficiencies (CE) at high current densities (CD). At 300 mA.cm−2 a CO-CE of 56% for a Ag GDE and a C2H4-CE of 94% for a Cu GDE are measured. The incorporation of the developed GDEs into a zero-gap assembly eliminates ohmic losses and maximizes EE, however the acidic environment of the ion exchange membrane inhibits CO2 reduction. As a compromise a thin liquid buffer layer between cathode and membrane is a prerequisite for a highly active conversion. We demonstrate that industrial relevant CDs with high CEs and EEs can only be achieved by moving beyond today’s research form catalyst development only to an integrated reactor design, which allows to exploit the viable potential of electrochemical CO2 reduction catalysts.

Fouling-resistant biofilter of an anaerobic electrochemical membrane reactor

Membrane fouling is a considerable challenge for the stable operation of anaerobic membrane-based bioreactors. Membrane used as a cathode is a common measure to retard fouling growth in anaerobic electrochemical membrane bioreactors (AnEMBR), which; however, cannot avoid the fouling growth. Here we report a strategy using the membrane as an anode to resist membrane fouling in an AnEMBR. Although aggravating in the initial stage, the fouling on the anode membrane is gradually alleviated by the anode oxidation with enriching exoelectrogens to finally achieve a dynamic equilibrium between fouling growth and decomposition to maintain the operation stable. A mesh-like biofilter layer composed of cells with less extracellular polymeric substance (EPS) is formed on the membrane surface to lower the trans-membrane pressure and promote the interception of the anode membrane. The membrane has high electron storage and transfer capacities to accelerate the oxidation of the intercepted fouling materials, especially, the redundant EPSs of the biofilter layer.