Activation of O by zero-valent zinc assisted with Cu(II) for organics removal: Performance and mechanism.

This study proposes a method to activate O by accelerating the corrosion process for zero-valent zinc (ZVZ) with the assistance of Cu(II), promoting the consecutive production of reactive oxygen species. The mechanisms for reactive oxygen species generation are clarified with metronidazole (MTZ) as the targeted pollutant. The outcome suggests the association of Cu(Ⅱ) and ZVZ presents an apparent cooperative activity, an enhancement of 85% in MTZ removal is attained for the ZVZ/Cu(Ⅱ) system after 10 min compared to that for ZVZ. Analysis of the mechanisms involved indicates that this improvement is due to the addition of Cu(Ⅱ), which can accelerate the corrosion of ZVZ. In addition, quenching experiments and electron paramagnetic resonance (EPR) technology show that superoxide radicals (·O) result in rapid MTZ degradation. The primary component that is liable for O activation and a certain amount of HO generation is verified to be ZVZ. Moreover, Cu(I) is detected in the ZVZ/Cu(Ⅱ) system, which arises from a direct reduction pathway driven by ZVZ and an indirect reduction pathway driven by active hydrogen atoms.