We struggle to recycle normal batteries without injuring or killing people. Lead-acid batteries contain literal plates of lead oxides, and we can't manage to keep that out of the water supply! I don't see how we'd do any better with silver nanoparticles.

Nothing I'm saying is meant to condemn recycling as a concept, by the way. Only to condemn technologies where disposal is dismissed with a shrug and a "idk just recycle it."