Revealing the degradation of atrazine in S-nZVI/peroxydisulfate system with density functional theory calculation

Sulfurization is usually applied for modifying nZVI to enhance the performance and overcome the aggregation, yet the discussions about specific effects seem to be scanty, such as the generation of reaction oxygen species (ROS) and the degradation of organics. Herein, sulfidated nanoscale zero valent iron (S-nZVI) was synthesized and used for the activation of peroxydisulfate (PDS), and the investigations were conducted based on the removal performance of S-nZVI/PDS system for atrazine (ATZ), including the generation of ROS and the characteristics transformation of S-nZVI. The results showed that S would affect the electron transfer process between S-nZVI and PDS as well as the generation pathways of ROS, thus realizing the brilliant degradation of ATZ through the roles of SO₄⁻, OH, and Fe(IV). Based on this, density functional theory (DFT) calculation was employed to analyze the reactivity, and then the possible degradation pathways of ATZ were proposed through the combination of DFT and liquid chromatography-mass spectrometry, demonstrating that the reactivity of CCl bond was important for ATZ degradation. This work provided the new insight into ATZ degradation through the S-nZVI/PDS system.