Sulfide-modified zero-valent iron activated periodate for sulfadiazine removal: Performance and dominant routine of reactive species production

In this work, sulfide-modified zero-valent iron (S-Fe-0) was used to activate periodate (IO4-, PI) for sulfadiazine (SDZ) removal. 60 mu M SDZ could be completely removed within only 1 min by S-Fe-0/PI process. Compared with other oxidants including H2O2, peroxymonosulfate (PMS), peroxydisulfate (PDS), S-Fe-0 activated PI exhibited better performance for SDZ removal but with lower Fe leaching. Compared with Fe-0/PI process, S-Fe-0/PI process could reduce more than 80% Fe-0 and PI dosage. Inorganic ions and nature organic matters had negligible effect on SDZ removal in S-Fe-0/PI system inducing its good SDZ removal efficiency in natural fresh water. 80.2% SDZ still could be removed within 2 min after 7th run. S-Fe-0/PI process also exhibited 2.5 - 20.1 folds enhancement for various pollutants removal compared with Fe-0/PI process. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical tests, and density functional theory (DFT) calculation were conducted to confirm the presence of sulfurs could enhance the reactivity of S-Fe-0 thus increased the efficiency of PI activation for antibiotics removal. Electron paramagnetic resonance spectroscopy (EPR) tests, radical quenching experiments, quantitative detection and DFT calculation were performed to illustrate the role of multiple reactive species in SDZ removal and the dominant pathway of multiple reactive species production. IO3 center dot , (OH)-O-center dot, O-2(-center dot), O-1(2), Fe-IV, and SO4 center dot- all participated in SDZ removal. (OH)-O-center dot played the major role in SDZ removal and the dominant routine of (OH)-O-center dot production was IO4- -> O-2(-center dot) -> H2O2 -> (OH)-O-center dot. Meanwhile, S-Fe-0/PI process could effi-ciently mineralize SDZ and reduce the toxicity. Comparison with other PI activation approaches and SDZ treatment techniques further demonstrated S-Fe-0 was an efficient catalyst for PI activation and present study process was a promising approach for antibiotics removal.

Automated summary

In this study, sulfide-modified zero-valent iron was used to activate periodate for the removal of sulfadiazine. The S-Fe-0/PI process was found to be highly efficient in removing SDZ, with minimal leaching of iron. Additionally, the process was able to mineralize SDZ and reduce its toxicity.