Comparison of physical characteristics of highly porous materialsduring their acoustic and traditional drying

A comparison was made of drying fine-porous silica gel grains in an acoustic-convective dryer of the ITAM SB RAS with convective drying in an air atmosphere at normal pressure and with a residual pressure of the furnace working chamber $p = 10^{-3}$ MPa. Changes in the morphology, structure, specific surface area, total pore volume and mechanical properties of the original, moistened and dried silica gel grains were recorded. It is shown that when the acoustic-convective drying mode used in the work occurs, intensive extraction of moisture from the sample occurs, which is accompanied by dehydration of the grain — fragments of grains are observed, macrodefects in the form of chips are found on the surface of the grains, main cracks are present in the structure of the material, the specific surface area decreases to $200$ m$^2$/g, a decrease in the total pore volume to $0.26$ m$^3$/g, or the absence of pores smaller than 100 nm, the mechanical strength of silica gel decreases to 96.25%.