wise pressure rise over the sample has been investigated at a constant underlying plate temperature of 35
C. The initial portion of the kinetic curves is consistent with Fick’s diffusion model: the amount of sorbed water
increases in proportion to the square root of the sorption time. This makes it possible to determine the effective
diffusivity of water (Deff). At small amounts of sorbed water (w < 0.19 g/g), Deff changes slightly. The diffusivity
of water in the composite pores (D) calculated for the same conditions is close to the Knudsen diffusivity of
water vapor in mesopores. The Deff value grows with an increasing water content of the composite; that is,
sorbed water accelerates water transport in the pores. This is likely due to the appearance of an extra diffusion
channel, namely, diffusion through the aqueous solution of the salt, whose formation begins on the silica gel
surface at w > 0.1 g/g. The contribution from this channel increases markedly when the amount of adsorbed
water is above 0.25 g/g. This can be explained by the formation of the “connected” phase of the solution in the
pores.