Three-dimensional porous defective MIP-202 composite aerogel for efficient Pb(Ⅱ) and Cd(Ⅱ) removal

Highly toxic Pb(Ⅱ) and Cd(Ⅱ) persist in water and soil, disrupting ecosystems while threatening human health through bioaccumulation. Metal-organic frameworks (MOFs) as adsorbents toward heavy metal ions have garnered significant research attention. However, their adsorption capacity and retrieval are limited by small pore size and powder form. Herein, we designed a defective MIP-202 composite aerogel (DMCA) to efficiently remove Pb(Ⅱ) and Cd(Ⅱ). Mixed ligand (mercaptosuccinic acid) and modulator (butyric acid) were involved in the synthesis of MIP-202, and competed with the original amino acid ligand for binding to Zr clusters leading to the disruption of the original structure of MIP-202 and defect formation. Defective MIP-202 (D-MIP-202) possessed larger BET surface area (from 35.79 to 129.57 m 2 /g) and pore size (from 6.16 to 11.78 nm). Moreover, D-MIP-202 powder and sodium alginate were synthesized into DMCA with abundant adsorption sites and porous structures to enhance the sorption capacities, which were 434.7 mg/g (Pb(II)) and 202.6 mg/g (Cd(II)). The adsorption process primarily occurs on the heterogeneous surface of the material and represents a spontaneous chemisorption behavior. The adsorption mechanism is attributed to chelation, and ion exchange. This study presents an effective strategy for the remediation of heavy metal ions in aqueous systems.