Satisfactory degradation of tetracycline by a pH-universal MnFe-LDH@BC cathode in electric Fenton process: Performances, mechanisms and toxicity assessments

The ubiquitous and ineffective treatment of antibiotics in aquatic systems leads to serious environmental problems, threatening ecology and human health. Herein, layered double metal hydroxides (LDH) and biochar (BC) were successfully combined through a facile hydrothermal method to prepare a novel pH-universal electric Fenton (EF) cathode (MnFe-LDH@BC). The developed MnFe-LDH@BC-EF system exhibited superior perfor-mance in the degradation of tetracycline (TC) (94.2%) than both of MnFe-LDH-EF (64.1%) and BC-EF system (67.0%) and showed a well-pleasing performance in a wide pH range. It was proposed that the nanostructures of LDH favored the multivalent cycle of Fe and Mn, promoting the electron transfer of BC as well as the release of Fe2+, leading to continuously generation of extensive free radicals and non-radicals. The co-existing ions (Cl-, NO3-, CO32-, HCO3- and H2PO4-) had different impact on the removal of TC. The studied system exhibited satis-factory degradation of various selected contaminants as well as fantastic stability in successive cycles. The possible degradation pathways were proposed and the toxicity of intermediate products were assessed by the Estimation Program Interface (EPI) Suite analysis. This work demonstrated the great potential of the developed cathode in water treatment area and provided insights into the utilization of biomass waste resources.

Automated summary

The combination of layered double metal hydroxides and biochar prepared a novel pH-universal electric Fenton cathode, which exhibited superior performance in the degradation of antibiotics and had a wide applicable range. Co-existing ions were found to have an impact on the degradation effect, and the toxicity of intermediate products was assessed.