Figure 3.

Behavior of CuS NP-glass samples upon immersion in water: (a) SEM image of a portion of a standard sample soon after preparation; (b) SEM image of a portion of the same sample after 24 h of immersion in water; (c) SEM image of a portion of the same sample after one week of immersion in water; (d) copper released from standard 21 × 26 mm samples in 5 mL of distilled water at different times (max: 1 week) expressed as micrograms released per cm² of surface(samples mean copper surface concentration: 0.5 (1) μg/cm²).