Synergistic Adsorption–Filtration of Aromatic Pollutants via Biodegradable PLA/MIL-68(Al) Mixed-Matrix Membranes

The complete removal of persistent aromatic organic pollutants from aqueous environments demands the development of sustainable and highly efficient filtration materials. In this study, novel bio-sourced mixed-matrix membranes (MMMs) were successfully fabricated by incorporating the highly porous metal–organic framework MIL-68(Al) into a biodegradable polylactic acid (PLA) matrix via a solvent-induced phase inversion method. The integration of MIL-68(Al) nanoparticles significantly tailored the membrane’s morphological structure, endowing the hybrid membranes with enhanced surface hydrophilicity (water contact angle reduced from 90.3° to 72.7°) and superior permeability. The pure water flux reached an optimal value of 42.2 L m−2 h−1 at a 15 wt.% MOF loading. Crucially, the hybrid membranes exhibited exceptionally high adsorptive removal performance for p-nitrophenol (PNP) and methylene blue (MB). Driven by the abundant accessible active sites of the MOF filler, the MIL-20/PLA membrane achieved a maximum equilibrium adsorption capacity of 121.03 μg/cm2 (36.90 mg/g) for PNP, representing a remarkable 25.7-fold enhancement over the pristine PLA membrane. Kinetic analyses confirmed that the adsorption process is strictly governed by pseudo-second-order kinetics, indicating a chemisorption mechanism dominated by hydrogen bonding and π–π stacking interactions. Furthermore, the optimized membranes demonstrated outstanding dynamic filtration efficiencies (>80%) and robust regenerability over multiple continuous operating cycles. This work not only highlights the synergistic interfacial effects between MOFs and biodegradable polymers but also provides a highly effective, eco-friendly, and sustainable membrane platform for the advanced remediation of organic-contaminated wastewater.