Simultaneous antimicrobial and adsorptive capabilities of a novel surface-modified NH2-MIL-101 (Cu) for sustainable wastewater remediation

Metal-organic frameworks (MOFs) are an emerging class of porous materials with remarkable surface area, tunable pore structures, and diverse chemical functionalities. In this study, we reported the green synthesis and comprehensive characterization of a novel modified NH₂-MIL-101 (Cu) derived from 2-aminoterephthalic acid, followed by post-synthetic modification with terephthalaldehyde to improve its adsorption capabilities. The synthesized Cu-MOF exhibited a very high specific surface area (2037.65 m²·g^-1, BET), a total pore volume of 0.7465 cm²·g^-1 and mesoporosity with an average pore diameter of 29.06 nm. SEM and TEM images showed uniform polyhedral particles with an average particle size of ≈ 85 ± 10 nm, while XRD patterns displayed well-defined diffraction peaks with the most intense reflection at ~ 2θ = 28-29°, confirming high crystallinity and preservation of the MIL-101 topology after modification. Under optimized conditions (10 mg adsorbent, 10 mL solution, room temperature and appropriate pH), the material exhibited high adsorption capacities of 230.1, 165.2, and 187.4 mg·g^-1 for crystal violet, methyl orange, and rhodamine B, respectively, attributable to its large porosity and functional surface groups. A plausible mechanism involving electrostatic interaction, π-π stacking, and coordination bonding is proposed for adsorption of dyes onto the modified MOF. The Cu-MOF maintained excellent structural stability and reusability, retaining over 92% of its initial adsorption capacity after five consecutive adsorption-desorption cycles, as confirmed by XRD patterns showing no noticeable framework collapse. This highlights its robustness and potential for sustainable wastewater remediation. In addition to dye removal, the material demonstrated antimicrobial activity, with MIC values of 4, 8, 32 and 128 µg/mL for P. aeruginosa, C. albicans, E. coli, and A. fumigatus, respectively, while no inhibition was observed against Gram-positive strains at concentrations up to 4096 µg/mL. The antimicrobial effect is likely attributed to Cu²⁺ ion release and electrostatic interactions leading to membrane disruption and ROS generation. These results highlight the potential of the synthesized Cu-MOF as a multifunctional and eco-friendly candidate for both wastewater treatment and biomedical applications.