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Study of evaporative drying of treated silica gels

Journal of Non-Crystalline Solids
Publication Date
DOI: 10.1016/j.jnoncrysol.2004.06.043


Abstract Studies were performed on silica gels synthesized in isopropanol to determine the parameters necessary to follow evaporative drying quantitatively, particularly during the last drying phase controlled by vapor diffusion in the gel nanostructure. As prepared and silanized gels were compared. Dynamic vapor sorption of isopropanol was used to determine adsorption isotherms and apparent diffusion coefficients in the silica network. A significant effect of surface modification (consisting in capping the silica surface with trimethylsilyl groups) has been observed. The diffusivity of solvent vapors was found to be very low, from 10 −9 to 10 −10 m 2 s −1, respectively, for treated and untreated samples, but in agreement with previously published works. Microcalorimetry confirmed a reduction in the affinity between the solid phase and solvent due to the silanization treatment. In parallel, evaporative drying experiments were conducted, recording the sample mass and taking photographs during the entire process of solvent evaporation. Comparison between untreated and treated samples during the last drying step showed how and when spring-back takes place for the latter.

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