Why does old blue silica gel turn opaque white?

Question

I searched on the internet and did not find a satisfactory answer. Most of the other beads are light pink. Can the white ones still be re-generated or they just lack their moisture inhibitor properties?

Answer 1

Silica gel acts as a dessiccant --- a substance that adsorbs water vapor from the atmosphere. Scientists place it in air-tight containers to prevent contamination of moisture-sensitive chemicals. Botanists and flower collectors use it to dry and preserve flower specimens. Most consumers would recognize it as the ingredient inside the small white pouches found packaged with new shoes. Pure silica gel exhibits a white or off-white color, but manufacturers sometimes dope it with traces of cobalt. Cobalt exhibits a bright blue color in anhydrous form, but turns pink in the presence of moisture. As such, the cobalt serves as an indicator that allows the user to visually determine when the silica gel gas is saturated with water. The adsorption of moisture in silica gel represents a reversible process. Silica gel has a great capacity of absorbing moisture. And as I mentioned on absorbing moisture it turns pink. And when it get old, it absorbs more moisture in it resulting a white silica.