Ok, its common knowledge that most of the time superman gets his power for the radiation of our yellow sun. lead is a material that is not only hard, but resistant to uv or raddiation. If you were to knock out superman with some kryptonite, would you be able to keep him prisoner (or kill by suffocation) in a sealed lead room underground?
@the_lunact_and_manic, this is a situation in which he is exposed to kryptonite until arriving, keeping him incapacitated. and just for pizzaz, lets say you were deadpool and you stabbed him with a kryptonite sword.
Lol, well, you would need a lot of gold kryptonite then.
The effect kryptonite has on him hasn't been consistent. Are we assuming it drained his energy too? If not, once he's in the room he's not getting any more energy but he's got all the rest he had stored (it's not bleeding his reserves as a red-sun appears to do). He could just smash his way out (likely with only a minute fraction of the energy he has stored).