Degradation mechanism of tetracycline using sulfidated nanoscale zerovalent iron driven peroxymonosulfate and metabolomic insights into environmental risk of intermediates products

Sulfide-modified nanoscale zerovalent iron (S-nZVI) has aroused increasing interest due to its excellent ability towards environmental decontamination. Heterogeneous catalytic degradation of tetracycline hydrochloride (TC-H) mediated by iron-based materials has been explored by previous researches. Yet, unknown role and degradation mechanism of tetracycline hydrochloride (TC-H) through S-nZVI driven peroxymonosulfate (PMS) need to be further investigated. In current research, the impacts of S-nZVI dosage, PMS dosage, initial pH, anions and humic acids were independently explored during TC-H degradation process. S-nZVI exhibited the high efficiency for activating PMS. TC-H degradation followed a pseudo-first order kinetics reaction with k(obs), at 0.1403 min(-1) . HA, Cl-, HPO42-, NO3- exhibited varied reduction of the reaction rates on TC-H removal. Besides, SO4 center dot- and center dot OH were dedicated to degrading TC-H, and SO4 center dot- was proved to be predominant one. The alteration of sulfide species from XPS analysis played a pivotal role in raising the electron transfer rate to improve TC-H degradation. Ten intermediates products were determined through HRMS and primary transformation mechanism involved in N-demethylation reaction, demethylation reaction, elimination reaction and hydrogenation reaction were proposed. Based on metabolomics analysis, up-regulated expression of carbohydrate metabolism, citrate cycle, CoA biosynthesis, fatty acid degradation and amino acid synthesis in Escherichia coli were significantly induced by the further products, whereas glutathione metabolism was significantly down-regulated, endorsing that potential toxicity induced by intermediates were weakened. To sum up, S-nZVI/PMS as a promising nano-water environmental remediation method could be feasible for emerging environment organic pollutants control.