Activation of peroxymonosulfate by cobalt-iron nanoparticles anchored on nitrogen-doped biochar for efficient removal of tetracycline from water: Free radical and non-free radical pathways

This study successfully synthesized a biochar composite of cobalt, iron, and nitrogen (FeCo@NBC), which was then utilized to activate peroxymonosulfate (PMS) for the removal of Tetracycline (TC). The surface morphology and physico-chemical properties of the synthesized FeCo@NBC catalyst were characterized using SEM, XRD, Raman, XPS and VSM. Studies were conducted into the effects of FeCo@NBC dosage, PMS concentration, initial pH, reaction temperature, co-existing anions on TC removal were investigated. Combining the results of electron paramagnetic resonance (EPR), XPS and quenching experiments, a possible catalytic mechanism for the degradation of TC by FeCo@NBC-activated PMS was proposed. The mechanism of radical-unradical synergism was elucidated, in which the non-radical pathway dominated by single-linear oxygen and electron transfer, and the possible degradation pathways of TC were speculated. In addition, the Co(II), Fe(II), graphite N and CO groups of FeCo@NBC are the main active sites. FeCo@NBC has strong anti-disturbance properties, low metal leaching, the ability to activate a variety of oxidants, and the ability to be recovered by magnetism, making it a new option for the resourceful use of agricultural waste and for the practical treatment of antibiotic wastewater.