Question

is it possible to regenerate silica gel using superheated steam? if possible, i understand that superheated steam provides enough enthalpy for adsorbed water to be released as vapor, but how can mass transfer of water from silica gel to steam happen, since steam has more water concentration than silica gel, so shouldn't mass transfer occur from steam to silica gel, not the other way around? (if it helps, perhaps we should think about zeolite 3A as liquid dessicant, instead of silica gel)

Answer 1

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Steam regeneration of Silica gel can be carried out and it is a practice too.

Although the most common regeneration method of silica gel is heating in an oven and drying at around 120-150 C.

In Steam regeneration, Super-heated steam is provided to silica gel that have already adsorbed water.

The heat of steam is utilized by water in the silica gel to vaporize. The vapors can no longer remain absorbed in the surface due to high temperature.

They will escape and diffuse into the Air.

There is no concentration gradient in water vapor content between Silica gel and Saturated steam as water exists as a liquid while it is adsorbed on the surface. So concentration gradient doesn't have much role to play in this scenario.

Due to the high diffusivity of water vapor in air, immediate diffusion will take place