Comparison of aerobic atrazine degradation with zero valent aluminum and zero valent iron

This study systematically compared the degradation of atrazine (ATR) with aerobic zero-valent aluminum (ZVAl/Air) and zero-valent iron (ZVI/Air) systems. By comparing the ATR degradation curves and rate in the ZVAl/Air and the ZVI/Air systems, a significant induction period was observed in the ZVAl/Air system, and the pseudo-first-order rate constant of ATR degradation in the second stage by ZVAl was 6.4 times faster than that by ZVI. The differences in ATR degradation patterns of the two systems stemmed from the different redox nature and electrical conductivity of aluminum (oxide) and iron (oxide). Reactive oxygen species measurement and electron spin spectra analysis indicated that more hydroxyl radical was generated through molecular oxygen activation in the ZVAl/Air system, leading to enhanced ATR degradation in the ZVAl/Air process. By analyzing the intermediates of atrazine degradation, we found that ATR underwent an oxidative dealkylation and hydroxyl-dechlorination degradation pathway, and the low toxicity cyanuric acid was the final product in both systems. However, aluminum ions released in the ZVAl/Air system exceeded the regulated standard value, which might cause environmental pollution. Finally, the pros and cons of potential environmental remediation of the ZVAl/Air and ZVI/Air processes were evaluated.