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

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 m(2)/g) and a low density (0.12 g/cm(3)). 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.