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

Abstract

• S-nZVI driven PMS exhibited an excellent performance to eliminate tetracycline. • Both SO 4 •− and •OH as dominant species were committed to degrading tetracycline. • Ten degradation intermediates were screened and determined by HRMS analysis. • Further intermediates products induced upmetabolism of carbohydrate, citrate cycle. • SO 4 •− based incomplete mineralization decreased the toxicity of tetracycline. 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 − , HPO 4 2− , NO 3 − exhibited varied reduction of the reaction rates on TC-H removal. Besides, SO 4 •− and •OH were dedicated to degrading TC-H, and SO 4 •− 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.