Fabrication of recyclable Pd@NH2-MIL-101/AOPIM-1 beads for sustainable catalytic water remediation

The widespread presence of toxic nitroaromatic compounds in industrial effluents demands advanced remediation strategies. Catalytic reduction is highly effective, while the practical application of powdered catalysts is limited by challenges in recovery and reuse. To overcome this issue, macroscopic Pd@NH 2 -MIL-101/AOPIM-1 porous composite beads were fabricated via a phase inversion method, combining the high surface area of NH 2 -MIL-101 with the excellent processability of amidoxime-functionalized polymers of intrinsic microporosity (AOPIM-1). The incorporation of NH 2 -MIL-101 enriches the composite with amino functional groups, thereby enhancing the adsorption and local enrichment of reactants. Furthermore, these nitrogen-rich sites provide robust anchoring points for the uniform dispersion of Pd nanoparticles, collectively boosting catalytic activity and structural stability. The beads exhibited outstanding catalytic activity for the reduction of nitroaromatics, achieving 99% conversion of 4-nitrophenol (4-NP) within 5 min. The catalyst also maintained excellent structural stability over multiple cycles and allowed easy separation. Furthermore, the catalyst exhibited over 90% efficiency in the reduction of other common nitroaromatic pollutants, underscoring its versatility and applicability in wastewater treatment. This work provides a sustainable and practical solution for wastewater treatment by transforming hazardous contaminants into valuable aromatic amines using an easily separable catalytic system.