Heterostructured MOF-Modified PAN Membranes with Efficient Oil–Water Separation and Photocatalysis

Abstract The discharge of oily wastewater poses a severe threat to both the environment and human health, necessitating the urgent development of high-performance oil–water separation membranes. In this study, heterogeneous-structured metal–organic frameworks (MOFs) (Al-MOF and Zn-MOF) were grown sequentially on the surface of polyacrylonitrile (PAN) nanofiber membranes via a hydrothermal method, these prepared membranes possess superior oil–water separation and self-cleaning properties. Owing to the synergistic interaction among the inherent adsorption of Al-MOF, the catalytic properties of Zn-MOF, and the high specific surface area of the PAN membrane, the PAN@Al-MOF@Zn-MOF composite membrane exhibits outstanding wettability, adsorption-photocatalytic performance, and exceptional oil–water separation efficiency (up to 97%). The as-prepared membrane displays excellent hydrophilicity (water contact angle (WCA) of 0°) and underwater superoleophobicity (underwater–oil contact angle of 160°). Furthermore, the introduction of heterogeneous-structured MOFs enhanced the photocatalytic activity through an interfacial charge carrier transport mechanism, achieving 92% degradation of methylene blue (MB) within 2.5 h. Crucially, this self-cleaning capability enables the membrane to maintain excellent cyclic stability, retaining 86.0% of its high permeation flux even after 10 continuous separation cycles. Meanwhile, the composite membrane maintained stable wettability even in complex environments. The composite membrane prepared in this research provides an efficient and sustainable strategy for the treatment of oily wastewater and the degradation of organic pollutants.