Construction of Photothermal Intelligent Membranes for Point-of-Use Water Treatment

For the removal of waterborne pathogens in remote areas and disaster emergency situations, point-source water treatment methods are more suitable. Photothermal sterilization is ideal for point-of-use (POU) systems, as it effectively eliminates pathogens without secondary pollution or bacterial resistance issues. By combining photothermal with membrane treatment, these membranes rapidly heat up under near-infrared (NIR) light, enabling both bacterial retention and sterilization. However, the decrease in membrane flux due to pore clogging during water treatment can significantly impact membrane efficiency. And adjusting the membrane pore size can significantly enhance flux recovery during cleaning, thereby restoring membrane efficiency. By synthesis multifunctional membranes that combine bacteria retention, sterilization, and flux recovery, it can meet the requirements of point-source water treatment: compact size, high efficiency, good safety, and easy maintenance. In this study, we developed an intelligent thermally responsive membrane (NIPAN@CNTs/PAN) by incorporating carbon nanotubes (CNTs) and forming a copolymer of N-isopropylacrylamide and polyacrylonitrile (NIPAN) coating into polyacrylonitrile membranes, offering dual functions of photothermal sterilization and self-cleaning. With 3% CNTs, the membrane achieves 100% sterilization within 6 min of NIR exposure, while the NIPAN layer's added roughness boosts photothermal efficiency, achieving 100% sterilization within 4 min. Rinsing at 50 °C improved flux recovery from 50% to 87% and reduced irreversible fouling from 49.7% to 12.9%, demonstrating stable performance over multiple cycles and highlighting its potential for long-term use in practical POU applications.