Functionalized MOF –Polymer Nanofibers for Water Remediation: Structure–Property Relationships and Dye Selectivity

Carboxylic acid‐functionalized membranes were fabricated by alkaline hydrolysis of electrospun polyacrylonitrile–Cu‐BDC (Cu‐BDC@PAN) nanofibers. The membranes were characterized using FT‐IR, SEM‐EDS, and XRD, confirming the successful incorporation of MOF while preserving crystallinity. XPS analysis revealed O 1s signals associated with carboxyl groups, alongside partial MOF degradation evidenced by CuO and Cu(OH) 2 species. Despite this structural alteration, the membranes exhibited selective adsorption of the anionic dye Reactive Black 5 (RB5), while showing negligible affinity for the cationic dye Rhodamine B (RhB). Adsorption of RB5 followed Langmuir isotherm behavior and pseudo‐second‐order kinetics, with a maximum capacity of 17.45 mg/g. These results highlight the potential of functionalized MOF–polymer nanofibrous membranes for targeted removal of anionic dyes from aqueous environments, even in the presence of partial MOF degradation. The combination of factors achieved, higher acid stability with the introduction of carboxylic groups after NaOH functionalization, enables efficient and selective RB5 adsorption in environments where conventional MOF@PAN systems are useless due to degradation. Importantly, the functionalization strategy employed here can be extended to other electrospun membranes with inherently low RB5 affinity, providing a versatile route to enhance dye adsorption in low‐pH wastewater treatment scenarios.