Some airlines and airports do stuff like this. Cathay used to support Change for Good. A while back, YYZ used to have FX exchange ATMs (looks like they've been replaced with full exchange counters) but there are also charity collection boxes (example at YYZ) for local charities at many airports.

That said, as someone mentioned above, I'd check to see if it's still legal tender. Some places have stopped accepting certain "instruments" as times have changed.