I have a collection of empty or nearly empty Iso-Butane canisters that have accumulated over the years. They are the 8 oz MSR type I use with my pocket rocket.
I never felt I should just throw them in the trash, since there is at least a remnant and perhaps a significant remnant of gas left in them.
What do you folks do? Is there an approved way to throw them out? Do any outdoor suppliers provide a recycling service?