Structural, textural and adsorption characteristics of nanosilica mechanochemically activated in different media

摘要

The structural, textural, and adsorption characteristics of mechanochemically activated (MCA) fumed silica A-300 as dry or water, ethanol, or water/ethanol-wetted powders (0.5g of a solvent per gram of silica) in a ball mill for 1-6h were studied in comparison with those of the initial powder. The MCA treatment enhances bulk density (ρ_b) of the powder (from 0.045g/cm~3 for the initial silica to 0.4g/cm~3 for 6h-MCA-treated water-wetted silica) depending on medium type and MCA time (t_(MCA)). Stronger effects are observed for the MCA treatment of water-wetted silica than of dry or ethanol- or water/ethanol-wetted samples. The MCA treatment weakly affects the specific surface area (S_(BET)). However, void (pore) size distribution, porosity, particle aggregation and size distribution in aqueous suspension, behavior of interfacial water, properties of poly(vinyl alcohol)/silica composites and adsorption of gelatin depend more strongly on the tMCA and ρ_b values. Some of the observed changes in the characteristics (e.g., gelatin adsorption) depend on the ρ_b value but are independent of the medium type used on the MCA. Other characteristics are nonlinear functions of both t_(MCA) and ρ_b values.