lugol

hi! I've been wanting to make a relatively harmless and interesting extraction in my homelab, and I've realized Lugol (a solution containing iodine and potassium iodide dissolved in water) might be a good starting material.
my objective is to separate the elemental iodine from the other components on Lugol, and ultimately obtain relatively pure elemental iodine (I₂) crystals at the end of my experiment.

starting material

Lugol's solution is an aqueous mixture that contians elemental iodine (I₂) and potassium iodide (KI).
the iodine isn't present exclusively as isolated I₂ molecules in the aqueous solution. rather, iodide ions (I⁻) supplied by the potassium iodide (KI) interact with molecular iodine (I₂) to form I₃⁻, called triiodide:
*I2+I−⇌I3−

why does it happen?

when KI (potassium iodide) dissolves in water, it separates into potassium ions (K⁺) and iodide ions (I⁻):
KI → K⁺ + I⁻

the iodide ion can interact with an iodine molecule afterwards. I₂ has an electron-rich distribution, and I⁻ can interact with it to form the triiodide ion, I₃⁻.
the important consequence is that I₃⁻ is much more comfortable existing in water than I₂ is. because I₃⁻ is a charged species, water can stabilize it much more effectively than it can neutral I₂, because water is a polar molecule, as you may know.
the iodide supplied by KI gives the iodine another, much more water-soluble form to exist as. this allows considerably more iodine to remain dissolved in the aqueous solution.