639 Figure 3 – Conceptual model illustrating chalcopyrite passivation as the result of multiple resistances to electron transfer and mass transport at the mineral–solution interface. The diagram shows two complementary perspectives. On the left, the processes occurring within a local surface patch are represented as resistances in series that collectively limit the dissolution current along a single reaction pathway T&5>F. These include the charge-transfer resistance at the mineral surface (VD>), the potentialdependent junction resistance V*(Y) associated with the formation of a semiconductor p–n junction at the chalcopyrite surface, the resistance of surface films (V3)H-) formed by products such as CuS, elemental sulfur, or iron oxyhydroxides, and the diffusion resistance (V,)33) associated with mass transport through the boundary layer. The total current through an individual pathway is therefore governed by the sum of these resistances and the applied potential drop Δ_.
RkJQdWJsaXNoZXIy MTM0Mzk2