Photothermal-driven pH-responsive fiber composite membrane for oil-wastewater purification

Oil spills and the discharge of organic wastewater have posed a severe danger to environmental security. To address this issue, various functional oil/water separation materials for wastewater purification have been developed. In this work, MXene/PPy was loaded on PP fiber by simple in-situ polymerization and vacuum-assisted filtration technology. Polypropylene was modified by dopamine (PDA) through in-situ polymerization, to improve the loading fastness of MXene/PPy on the surface of PP. To increase the durability of the fiber membrane, the pH-responsive polymer (PDM) was simply immersed on the outer layer. The successfully prepared PP-MXene/PPy-PDM has excellent pH response and photothermal conversion performance. When pH=2, the water contact angle (WCA) was 52°. When pH=12, WCA was 125°. The surface of PP-MXene/PPy-PDM was heated to 104.6℃ in ten minutes under the irradiation of 2 kW·m-2. PP-MXene/PPy-PDM could continuously separate oil/water mixture for 12 hours, and the highest separation flux was 3.87 kg·m-2·h-1. Moreover, PP-MXene/PPy-PDM has excellent stability, corrosion resistance and recyclability. This study provided a new strategy for preparing intelligent responsive fiber composite membrane for oil-water separation, which has a wide range of practical applications in the treatment of oily wastewater.