Yes, the cobalt-free blue silica gel desiccant will change from blue to red. The main reason for the discoloration is that Congo red is added to the silica gel. Congo red itself is used as an acid-base indicator. The discoloration range is 3.5 to 5.2, and the alkali state is Red, blue-purple in acid state. This kind of blue silica gel containing organic pigment indicator, which is safer than traditional silica gel containing cobalt chloride.
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