Hybrid Preceramic Aerogels for Oil and Solvent Cleanup

Abstract

This study presents the first synthesis and characterization of monolithic hybrid preceramic aerogels using distinct drying techniques: ambient pressure (ambigels) and CO₂ supercritical drying. Polymeric ambi/aerogels, derived from polyhydromethlysiloxane (PHMS) and divinylbenzene (DVB), are processed at 200 °C, while hybrid ceramic-polymer (ceramer) is produced through pyrolysis at 600 °C. Despite variations in drying methods, polymer and ceramer ambi/aerogels exhibit comparable microstructural characteristics, bulk density, pore size and volume, and specific surface area (542–841 m² g⁻¹). Polymeric and ceramer ambigel with 90 vol% total porosity yield a compressive strength, reaching 2.5 MPa, demonstrating a low thermal conductivity of 0.046 W m⁻¹ K⁻¹. Sorption tests are conducted using oil and organic solvents in aqueous media to benefit their high hydrophobicity (112° < θ < 142°). Aerogels exhibit high sorption capacities: 13.17 g g⁻¹ for sesame oil, 11.74 g g⁻¹ for toluene, and 9.19 g g⁻¹ for n-hexane. The sorption rate for the oil is nearly 10 times slower than that for toluene and n-hexane. Regarding regeneration and reusability, polymer and ceramer aerogels show consistent sorption properties cycles tested for n-hexane and toluene.