Fe3O4@CNT as a high-effective and steady chainmail catalyst for tetracycline degradation with peroxydisulfate activation: Performance and mechanism

Confining metal oxide nanoparticles (NPs) in carriers such as carbon nanotubes (CNTs) has become a novel strategy for designing highly efficient and stable non-noble metal chainmail catalysts. In this study, Fe3O4 NPs were confined in the chainmail of multi-walled CNTs to prepare Fe3O4@CNT magnetic nanocomposite with confinement effect, and peroxydisulfate (PDS) was activated to degrade tetracycline (TL) in aqueous solution. Under the conditions of 20 degrees C, pH0 = 7, 0.5 mM PDS and 0.4 g/L Fe3O4@CNT, TL degradation efficiency of 98.1% could be achieved by radicals (center dot OH, SO4 center dot-, O2 center dot- ) and non-radicals (1O2) generated in the system. Stable carbon-layer structure can protect Fe3O4 NPs inside the chainmail from the influence of reaction environment. TL degradation efficiency still reached 80.2% after five cycles, and the leaching of Fe ions was less than 10 mu g/L during each cycle. Electrochemical analysis and density functional theory (DFT) calculations show that electron transfer from active Fe3O4 NPs to the carbon layer to motivate the catalytic activity of carbon surface. This work will provide an innovative path for the application of chainmail catalysts in nano-water environmental remediation.

Automated summary

In this study, Fe3O4 NPs were confined in multi-walled CNTs to prepare Fe3O4@CNT magnetic nanocomposite, which showed high efficiency in degrading tetracycline (TL) in aqueous solution by activating peroxydisulfate (PDS). The stable carbon-layer structure protected the Fe3O4 NPs inside the chainmail, leading to consistent TL degradation efficiency and minimal leaching of Fe ions during multiple cycles. The electron transfer from Fe3O4 NPs to the carbon layer motivated the catalytic activity of the carbon surface, providing an innovative approach for environmental remediation in nano-water applications.