Project talk:Deactivating a ferric chloride solution
Ferric Chloride is convenient for small projects, but it is used up and disposal is a pain. An alternative is an etchant that can be regenerated by adding HCl and bubbling air through it.
I understand from some sources that adding HCl to Ferric Chloride will also regenerate it and eventually the etchant changes to CuCl as above. I don't know how carefully that procedure needs to be managed, or whether it's better to start directly with the CuCl bath.