Tailoring mechanical and surface property of Al2O3 fiber membranes through rare earth doping for enhanced oil-water separation

Flexible hydrophobic Al 2 O 3 fiber membranes doped with rare earth elements (La, Sm, Ho) were successfully fabricated via electrospinning, and the impact of rare earth doping on their mechanical and surface properties was systematically investigated. The incorporation of rare earth elements effectively suppresses Al 2 O 3 grain growth, relieves grain boundary stress, and consequently enhances the flexibility and tensile strength of the membranes. Notably, the Ho-Al 2 O 3 membrane exhibits the best flexibility and tensile strength (1.08 MPa). Furthermore, rare earth doping induces a transformation to hydrophobic surfaces for the La-Al 2 O 3 , Sm-Al 2 O 3 , and Ho-Al 2 O 3 fiber membranes, as evidenced by water contact angles of 149°, 137°, and 142°, respectively. This hydrophobicity is attributed to the formation of rare earth oxides on the fiber surface, which increases hydrocarbon affinity and lowers surface energy. The resulting doped membranes demonstrate excellent antifouling performance, achieving high permeation flux and separation efficiency in oil-water separation. The La-Al 2 O 3 membrane exhibits the highest flux (2921 L/(m 2 ·h)) and efficiency (98.4 %), owing to its superior surface hydrophobicity. These findings provide a mechanistic foundation for tailoring the microstructure and wettability of ceramic fiber membranes through rare earth doping, offering a promising strategy for advanced oil-water separation.