Effects of reaction parameters on the preparation of P4VP/SiO₂ composite aerogel via supercritical CO₂ drying

Abstract Herein, crosslinked poly (4‐vinylpyridine)/SiO₂ (P4VP/SiO₂) composite aerogel, an organic‐inorganic interpenetrating network, was successfully prepared by means of the sol‐gel process, acid‐base interaction method, and supercritical CO₂ drying process. In this novel composite aerogel, SiO₂ was used as an inorganic material, and nitrogen‐containing heterocyclic polymer was used as the active component. The effects of aging time, monomer ratios, solvent usage, and cross‐linker ratios were analyzed to obtain the optimal conditions for the P4VP/SiO₂ aerogel formation. The as‐prepared aerogel was characterized by using FT‐IR, XRD, Brunauer‐Emmett‐Teller (BET) analysis, and SEM analysis. Results showed that the aging time of 48 h, tetraethoxysilane (TEOS)/4‐vinylpyridine (4‐VP) mass ratio of 2:1, and diethylene glycol dimethacrylate (DEGDMA) content lower than 20 wt% were required to ensure the best porous amorphous structure of the product. These optimal conditions endowed the product with a relative high BET specific area (314 m²/g) and a low density (0.12 g/cm³). The adsorption performance of P4VP/SiO₂ was investigated via its capacity to remove Cu(II) from wastewater. Results showed that the adsorption capacity of up to 85 mg/g was attained under neutral conditions and the adsorption process highly follows the pseudo‐second‐order kinetics model.