Electrochemical synthesis of ultra-flexible PES/HKUST-1 composite membranes for wastewater treatment

Electrochemical synthesis of polymer/MOF composite membranes holds great potential for practical applications, yet the preparation of flexible and dense MOF layers remains a challenge, which is crucial for achieving practicality. Herein, a novel ultra-flexible polyethersulfone (PES)/Cu-based metal–organic framework (HKUST-1) composite membrane has been fabricated via an electrochemical synthesis method. Various reaction conditions, including voltage, stirring speed, and reaction time, were systematically investigated to elucidate their influence on crystal growth and the resulting membrane uniformity. The characterization results showed that high voltage and moderate stirring as well as are conducive to obtaining uniform fine crystals. Additionally, a relatively extended reaction time is advantageous for achieving a more continuous and denser MOFs membrane with outstanding flexibility. The optimized membrane possesses an excellent separation flux (2.81 × 103±32 L m−2 h−1·bar−1) and efficiency (99.7 ± 0.3%) for n-hexane/water mixtures, as well as excellent photodegradation efficiency (>99%) for methylene blue (MB). Remarkably, the optimized membrane exhibits remarkable scalability and stability, maintaining superior separation performance even after being rolled up 10 times with a curvature of 200 m−1. This suggests that it has great potential for practical applications in complex environments.