Iodophor is an amorphous mixture of iodine and povidone. Polyvinylpyrrolidone can dissolve and disperse 9%~ 12% iodine, and it is purple-black liquid at this time.

Lemonade contains citric acid (C6H8O7). Citric acid is an oxidant and iodine is a strong reducing agent. Monomer iodine in iodophor reacts with citric acid to generate hypoiodic acid, and the hydroxyl group on citric acid is iodinated, so there is no monomer iodine in the solution.

So the color of iodophor disappeared.