Multinetwork aerogels with in-situ grown UiO-66: Efficient adsorption of diclofenac sodium and mechanism decoding

Diclofenac sodium (DCF) is a novel pollutant that poses a significant environmental threat. Aerogels effectively adsorb diclofenac sodium, but their low density and high porosity exhibit poor adsorption and mechanical properties during adsorption. To overcome the limitations of traditional aerogels, specifically their poor structural integrity and inadequate adsorption performance, multinetwork aerogels were fabricated through successive integration of sodium alginate (SA) with Ca²⁺, chitosan (CS) with SA, and polyethyleneimine (PEI) with CS, followed by in situ formation of UiO-66@SA/CS/PEI. The results show that the multinetwork structure in the material dramatically enhances the aerogel's stability, which has been greatly improved. After amino modification, the maximum adsorption capacity reached 775.9 mg/L, 2.6 times that of the single network aerogel. A combination of adsorption modeling, molecular simulation and material structure characterization was used to analyze the adsorption mechanism in depth. Analysis revealed that the adsorption mechanism involved a heterogeneous endothermic process, predominantly governed by chemisorption accompanied by synergistic physicochemical interactions. The π-π EDA interaction, metal (Zr)-π interaction, electrostatic interaction, coordination of Zr with O and Cl, and hydrogen bonding were identified. Interference experiments show that UiO-66@SA/CS/PEI has good stability in different environments. This study provides new ideas for the synthesis and adsorption mechanism research of MOF-based poly-network aerogels, as well as theoretical support for the direction of material structure optimization and selective adsorption of DCF.