The reason it works is that coconut charcoal is in adsorbent.
adsorbent ad·sor·bent (ād-sôr'bənt, -zôr'-)
Capable of adsorption. n.
An adsorptive substance.
A pharmacological substance capable of attaching other substances to its surface without any chemical action.
An antigen or antibody used in immune adsorption.
adsorb ad·sorb (ād-sôrb', -zôrb')
v. ad·sorbed, ad·sorb·ing, ad·sorbs
To take up by adsorption.