La-doped flexible hydrophobic Al2O3 fiber membranes: preparation, properties, and oil–water separation performance

In this study, a La-doped flexible hydrophobic Al 2 O 3 fiber membrane was fabricated via electrospinning technology, and the influence of La doping on the mechanical properties and surface wettability of the Al 2 O 3 fiber membrane was systematically investigated. The results showed that the La-doped modified alumina nanofiber membrane has tunable fiber diameters (180–480 nm) and a highly interconnected porous network, which enhanced the efficiency and flux of oil–water separation. The incorporating an appropriate amount of rare earth La atoms, specifically at a La/Al atomic ratio of 0.125 (La-Al 2 O 3 -2), effectively enhanced the flexibility and tensile strength of the membrane. Concurrently, hydrophobic La 2 O 3 formed on the fiber surface, which transformed the membrane from hydrophilic to hydrophobic. As a result, the La-doped Al 2 O 3 membrane exhibited excellent anti-fouling performance, high permeation flux, and efficient oil–water separation. However, excessive La addition led to a significant decline in the flexibility and tensile strength of the Al 2 O 3 fiber membrane, whereas the hydrophobic surface was largely preserved. Among all samples, the La-Al 2 O 3 -2 fiber membrane exhibited superior flexibility and tensile strength. In oil–water separation applications, it achieved a high permeation flux of 2921 L/(m 2  ·h) and a separation efficiency of 98.4%; meanwhile, the good reusability was also obtained. Graphical abstract