Highly dispersed natural Goethite/Fe3O4 heterogeneous Fenton-like catalyst for efficient tetracycline degradation: Rapid accumulation of hydroxyl radicals by Fe-O-Si bonds

A highly dispersed catalyst (Fe3O4/NFe) was prepared with Fe3O4 and natural goethite (NFe) to remove TC in the heterogeneous Fenton-like system. A large amount of =Si-O-Si on NFe could be destroyed by the grinding method to produce SiO center dot on the surface. Fe3O4 nanoparticles were successfully grown on the NFe with the formation of Fe-O-Si bonds, the Fe3O4/NFe retained the magnetic performance and the larger dispersion from predecessors. In the Fe3O4/NFe/H2O2 process, the degradation performance of tetracycline (TC) could reach 90.1% in 30 min. Moreover, the toxicity of TC and its intermediates was estimated in ECOSAR software. The ESR analysis and quenching experiments revealed the contribution of center dot OH, HO2 center dot, and SiO center dot in TC removal. A part of center dot OH, HO2 center dot in solution could decompose TC, and the =SiO center dot on surface also directly remove TC. The strong interactions of Fe-O-Si bonds improved the generation of abundant center dot OH, and the total concentration of center dot OH by Fe3O4/NFe in 30 min is 244.7 mu mol/L. In DFT analysis, the electrons redistribution between Fe3O4 and NFe could easily provide the electrons to activate H2O2, and improved the adsorption of H2O2 in Fe3O4/NFe/H2O2 system. The removal rate of TC still reached 73.3% by Fe3O4/NFe after five cycles. In the present work, this Fe3O4/NFe has been shown to be a promising alternative to traditional homogeneous Fenton method.

Automated summary

In this study, a highly dispersed catalyst (Fe3O4/NFe) was prepared using Fe3O4 and natural goethite (NFe) for the removal of tetracycline in a heterogeneous Fenton-like system. The grinding method was used to destroy a large amount of =Si-O-Si on NFe, resulting in the production of SiO center dot on the surface. Fe3O4 nanoparticles were then grown on NFe, forming Fe-O-Si bonds. The Fe3O4/NFe catalyst showed excellent degradation performance for tetracycline and has the potential to replace traditional homogeneous Fenton methods.