Will the performance of color-changing silica gel decrease after regeneration?

The colour shifting silica gel will gradually lose its performance following regeneration. The microporous structure is slightly damaged during each regeneration, and the damage accumulates and weakens the adsorption capacity with time, especially when the regeneration temperature is too high or the number of regeneration cycles is too high.

1. Why does performance degrade with regeneration?

Fatigue in microporous structure: The silica framework is subjected to microcracks due to the cyclic moisture absorption and dehydration, resulting in the collapse of part of micropores and the decrease of specific surface area.

Loss of indicator: The cobalt chloride (blue silica gel) is easily oxidised at high temperature and the color-changing sensitivity decreases with repeated heating;

Physical breakage: During heating and handling, the friction between the particles causes powder, leading to a decrease in the effective volume of adsorption.

Experimental findings indicate that in general the adsorption capacity after 5 standard regeneration cycles reduces to 70-80 % of the starting value and can fall below 50 % after more than 10 cycles.

 

2. Three Factors that Speed up Performance Degradation

4th Factor

Impact Details

Regeneration temperature >120 °C

Decomposes indicators and sinters silica gel. Colour recovery is not complete after 1-2 cycles.

Early Regeneration (Deep Moisture Absorption)

Water molecules are trapped in the micropores and difficult to remove, resulting in partial regeneration; leftover moisture hinders future adsorption.

Frequent regeneration (i.e., more than once every month)

Increases ageing by 30-50% in high humidity environment (e.g. rainy season in Wuhan).

Ideal: dry atmosphere, 110℃ consistent temperature bake out, prompt treatment; can sustain steady performance for the first 3-5 regeneration cycles.

 

3. How to Determine whether Performance Has Deteriorated After Regeneration

Incomplete Colour Recovery: Greyish white or dark red regions after heating;

Slower moisture absorption rate: the change of colour is slower when put in a humid atmosphere;

Less time to dry Less time to stay dry in a sealed container;

Particle Powdering: Readily powders on squeezing indicating structural deterioration.

Practical advice: Tag the "Number of Regenerations". After 5+ regenerations, focus on performance monitoring. Use new silica gel for precise moisture protection Replace with new silica gel when used for precision moisture protection