Degradation of atrazine by catalytic ozonation in the presence of iron scraps: performance, transformation pathway, and acute toxicity

Abstract

Degradation of atrazine by catalytic ozonation in the presence of iron scraps (ZVI/O3) was carried out. The key operational parameters (i.e., initial pH, ZVI dosage, and ozone dosage) were optimized by the batch experiments, respectively. This ZVI/O3 system exhibited much higher degradation efficiency of atrazine than the single ozonation, ZVI, and traditional ZVI/O2 systems. The result shows that the pseudo-first-order constant (0.0927 min−1) and TOC removal rate (86.6%) obtained by the ZVI/O3 process were much higher than those of the three control experiments. In addition, X-ray diffraction (XRD) analysis indicates that slight of γ-FeOOH and Fe2O3 were formed on the surface of iron scrap after ZVI/O3 treatment. These corrosion products exhibit high catalytic ability for ozone decomposition, which could generate more hydroxyl radical (HO•) to degrade atrazine. Six transformation intermediates were identified by liquid chromatography-mass spectrometry (LC-MS) analysis in ZVI/O3 system, and the degradation pathway of atrazine was proposed. Toxicity tests based on the inhibition of the luminescence emitted by Photobacterium phosphoreum and Vibrio fischeri indicate the detoxification of atrazine by ZVI/O3 system. Finally, reused experiments indicate the approving recyclability of iron scraps. Consequently, the ZVI/O3 system could be as an effective and promising technology for pesticide wastewater treatment.