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

Abstract

Herein, crosslinked poly (4-vinylpyridine)/SiO 2 (P4VP/SiO 2 ) composite aerogel, an organic-inorganic interpenetrating network, was successfully prepared by means of the sol-gel process, acid-base interaction method, and supercritical CO 2 drying process. In this novel composite aerogel, SiO 2 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/SiO 2 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/SiO 2 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.

Efficient reinforcement of wet gel by embedded polymer as newly approach for silica aerogel

“…The presence of surface silanol groups leads to water adsorption, so the appeared bands around 1633 and 1637 cm −1 at both spectra are corresponded to deformation vibrations of physically absorbed water on the surface 36 . The intense band around 1107 and 1108 cm −1 are due to the both transversal and longitudinal optical modes of asymmetric stretching vibrations of the SiOSi covalent bonds, which is expected for the silica materials and proves the formation of a silica network structure 37 . Furthermore, the absorbs related to symmetric stretching vibrations and bending mode of silicon‐oxygen covalent bonds observe around 468 and 804 cm −1 at PVA‐ip‐SiO 2 network and around 470 and 809 cm −1 at silica aerogel, respectively.…”

“…36 The intense band around 1107 and 1108 cm −1 are due to the both transversal and longitudinal optical modes of asymmetric stretching vibrations of the Si O Si covalent bonds, which is expected for the silica materials and proves the formation of a silica network structure. 37 Furthermore, the absorbs related to symmetric stretching vibrations and bending mode of silicon-oxygen covalent network, which showed an almost complete degradation at temperatures above 600 C. 38 These appeared bonds have been proved the successfully formation of silica aerogels with an appropriate purity.…”

Composite Aerogel Comprised of Sodium Alginate and Bentonite via Supercritical CO2 Drying: An Efficient Adsorbent for Lysozyme

“…Supercritical drying yields aerogels that are endowed with higher porosities and higher surface areas when compared to freeze drying and ambient pressure drying [ 6 ]. In our previous study, we developed a poly (4-vinylpyridine) crosslinked SiO 2 (P4VP/SiO 2 ) composite aerogel obtained through supercritical CO 2 drying, which had a specific surface area of 314 m 2 /g and was endowed with an enhanced adsorption capacity for copper ions [ 7 ].…”