Novel hollow fiber membrane for synchronous wastewater treatment and CO2 electroreduction to ethanol

A novel hollow fiber membrane containing a carbon-coated CuO x (CuC-HFM) was prepared for in-situ CO 2 electrochemical reduction to ethanol during wastewater treatment. The ratio of Cu-based metal organic framework/carbon black of 1/1 was relatively optimal (Cu 1 C 1 -HFM) due to higher pure water permeance (24.62 L m −2  h −1 bar −1 ), better hydrophilicity (contact angle of 60.00°), and more ethanol yield (165.22 mg L −1  m −1 ) at −2.5 V with KOH as electrolyte. For control group (Cu 2 C 1 -HFM and Cu 1 C 2 -HFM), they were 76.50°/89.10°, 3.90/4.42 L m −2  h −1 bar −1 , 64.85/57.32 mg L −1  m −1 , respectively. The peaks of Cu (002) crystal plane, Cu 2+ electronic orbits, covalent bonds between C and O, and CuO x were appeared on prepared membrane. The CuO x could strongly adsorb CO and subsequently carbon shell could selectively produce HOCCH and HOCHCH, which were benefit for CO 2 electro reduction to ethanol. Therefore, the Cu 1 C 1 -HFM owned higher ethanol production (88.50 g L −1  m −2 h −1 ) during filtrating anaerobic supernatant. Meanwhile, the membrane could reject 97.2 % COD with only 14.7 % membrane flux loss. The membrane without bias suffered 27.1 % flux loss. This system gave a new thought for CO 2 electro reduction and the CuC-HFM had a promising employment in anaerobic bioreactor in the future.