Shell-core MnO2/Carbon@Carbon nanotubes synthesized by a facile one-pot method for peroxymonosulfate oxidation of tetracycline

In this study, a new type of MnO2/carbon@carbon nanotubes (MnO2/C@CNT) shell-core nanohybrid for peroxymonosulfate (PMS) activation was synthesized by a one-pot method, which simultaneously achieved the synthesis of MnO2 and assembly of components. Tetracycline (TC) degradation by MnO2/C@CNT-PMS was enhanced obviously, and MnO2/C@CNT (1.75:1)-PMS systems exhibited the best TC degradation efficiency (85.6%) at 10 min. In addition, the effects of catalyst dosage, PMS dosage, initial pH, reaction temperature, and co-existing ions on the degradation of TC were investigated. The stripping and insertion of the nanocarbon during the synthetic process were the basis for the enhancement of the Mn (III)/Mn (IV) ratio and surface -OH groups, which further accelerated electron transfer and the conversion of Mn and O species. EPR analysis along with the free-radical quenching experiments confirmed the presence of SO center dot-4 and center dot OH during the catalytic reaction, among which SO center dot-4 was the main active specie. Moreover, a comprehensive toxicity assay and prediction were performed based on bioluminescence inhibition experiments and the Ecological Structure Activity Relationships (ECOSAR) program. Finally, reasonable degradation pathways of TC were proposed based on LC-MS analysis.

Automated summary

The new MnO2/carbon@carbon nanotubes (MnO2/C@CNT) shell-core nanohybrid synthesized in this study showed enhanced degradation of tetracycline (TC) with MnO2/C@CNT-PMS systems exhibiting the best TC degradation efficiency at 85.6% in 10 minutes. The stripping and insertion of nanocarbon during synthesis enhanced electron transfer and conversion of Mn and O species, with SO center dot-4 identified as the main active specie during the catalytic reaction. LC-MS analysis was used to propose reasonable degradation pathways of TC.