In acidic conditions, with a pH less than 4.6, the chitosan amine group acquires a positive charge and dissolves due to interpolymer repulsion and the absorption of chitosan water molecules. We mainly use Acetic acid.

To dissolve chitosan in hydrochloric acid (HCl) at pH 5, prepare a dilute HCl solution (around 0.1 M) and gradually add chitosan while stirring continuously, monitoring the pH. Adjust with small amounts of weak base if necessary to maintain the desired pH during dissolution.