Conversion of CoNiFe-LDH to CoNiFe-MOF/LDH as catalyst for efficient heterogeneous electro-Fenton degradation of sulfonamide antibiotics

The widespread use of antibiotics leads to spread of resistance bacteria and genes in natural water and has a potential threat to human health. Herein, a nanorod CoNiFe-MOF/LDH was synthesized using a self-sacrificial strategy and employed to degrade sulfamethazine (SMT) by heterogeneous electro-Fenton (HEF). The conversion of CoNiFe-LDH to CoNiFe-MOF/LDH resulted in a significant enhancement of specific surface area (from 13.96 to 32.26 m2 g-1) and electroactive surface area (from 2.20 to 4.22 mm2), and the degradation rate of SMT increased from 88.53% to 98.41% within 60min. The free radical capture experiments indicated that ·OH and 1O2 played a significant role in the HEF process. The CoNiFe-MOF/LDH catalyst could be recycled 5 times with degradation rate of over 90%, it also demonstrated excellent resistance towards inorganic ions and humic acid. In addition, the CoNiFe-MOF/LDH exhibited remarkable degradation efficiency for 8 sulfonamides (over 89%). Mass spectrometry analysis indicated that SMT was oxidatively degraded via three possible pathways. According to the analysis of Toxicity Estimation Software Tool, the acute toxicity of SMT was effectively weakened. The CoNiFe-MOF/LDH catalyst has potential application prospect in wastewater treatment.