Iron-nitrogen co-doped biochar (FeN@BC) as particle electrode for three-dimensional (3D) electro-peroxydisulfate process for tetracycline degradation

In this work, a three-dimensional electrode material (FeN@BC) was prepared by doping iron-nitrogen sites into biochar for activating peroxydisulfate (E-FeN@BC-PS). The scanning electron microscope, x-ray diffractometer, Fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopy results of FeN@BC proved that Fe–N sites were successful doped into BC. Electrochemical analysis indicated that FeN@BC could enhance the electron transfer in the electrochemical process. A significant synergistic effect (SI = 12.46) was observed in the E-FeN@BC-PS system. Tetracycline (TC) was almost removed completely within 30 min in optimal operating parameters. Radical scavenging experiments showed that ·OH, SO4●−, O2●−, and 1O2 all contributed to TC degradation. The cyclic experiment and characterizations before and after the recycle showed that the FeN@BC in the three-dimensional electrode system exhibited excellent stability and reusability, and electricity had an obvious protective effect on the FeN@BC materials. This study revealed the synergistic catalytic mechanism of metal and heteroatomic hybrid materials as three-dimensional electrodes in persulfate activation, promising the development of sustainable and efficient water treatment technology.