Material for moisture moderation

Question

Do you know of any material that can moderate the level of moisture of its local environment?

Example: if the desired moisture level is 30% and the local environment of the material is at 6% the material should extract moisture to achieve 30% moisture. If local environment is at 60% the material should retract.

The only material that I know of with properties similar to that, is zeolite. Do you happen to know any other of if zeolite can be used to maintain a certain level of moisture?

Thank you very much.

Answer 1

There are materials called desiccants which absorb water. And an open cup of liquid water can sometimes serve as a convenient source of humidity. But if you are trying to regulate the activity of water in a system to a particular level, then you may have to introduce additional phases into your system. You'll have to design a system which gives you the activity of water you're seeking and satisfies the Phase Rule.

It depends upon the details of the system you are trying to control (e.g. buffer) and it's generally not possible to arbitrarily specify all the degrees of freedom independently.

For example, you may be able control the humidity to a specific value, but not independently of temperature or pressure.