Hydrophobic silica aerogels originated from feldspar powder under atmospheric pressure

In this paper, silica aerogel with excellent performance was prepared by using feldspar powder as silica source, combined with sol-gel method and atmospheric pressure drying. Using scanning electron microscopy (SEM), aperture and specific surface area analyzers, X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), Fourier transform infrared spectroscopy (FT-IR), comprehensive thermal analysis (TG-DSC), thermal conductivity, and other material analysis techniques, the optimum activation conditions (activation time, powder-alkali ratio, activation temperature) of feldspar powder and their effects on the activation rate were investigated. The physicochemical properties of silica aerogels catalyzed by different concentrations of acid were also studied. The results show that the optimal conditions for activating feldspar powder are an activation temperature of 800 °C, an activation time of 60 min, and a powder-alkali mass ratio of 5:4. When the aerogel synthesis was catalyzed with 2 M hydrochloric acid under these optimal activation conditions, the specific surface area and pore volume of the aerogel reached 941 m²/g and 5.11 cm³/g, respectively. The surface contact angle and thermal conductivity were 162° and 0.023 W/m·K, respectively, indicating excellent hydrophobicity and thermal insulation properties.