Highly dispersed FeN-CNTs heterogeneous electro-Fenton catalyst for carbamazepine removal with low Fe leaching at wide pH

Iron-based catalysts usually have a narrow pH application range and are easy to agglomerate and inactivate in the heterogeneous electro-Fenton (Hetero-EF) process. In this work, FeN-carbon nanotubes (FeN-CNTs) catalysts with highly dispersed FeNx sites and tubular structures were synthesized. This FeN-CNTs/Hetero-EF process extended the pH application range to 3–11 with low metal leaching (0.4 mg/L at pH 3) and negligible homogeneous contribution. Compared with nitrogen-doped carbon (N-C, prepared with the same procedure but without FeCl 3 ⋅6H 2 O precursor), its pseudo-first order reaction rate constant was increased by 4.4 times, suggesting that the uniformly dispersed active site FeNx played a key role in the catalytic activation of H 2 O 2 and the efficient degradation of carbamazepine (CBZ). Effective CBZ removal (10 mg/L) could be achieved at low current density (1.25 mA/cm 2 ) and catalyst dosage (50 mg/L) in FeN-CNTs/Hetero-EF. The capture experiments and EPR tests confirmed the existence of various active species such as • OH and 1 O 2 , among which • OH played a dominant role in the degradation of CBZ. FeN-CNTs significantly improves the removal of pollutants under a wide pH range, showing broad application prospects.