Iron pyrophosphate doped carbon nanocomposite for tetracycline degradation by activation of peroxymonosulfate

Tetracycline (TC) is hard to degrade and is usually present in the aqueous environment due to abuse. It is necessary to find effective treatment methods for TC pollution. In this work, Iron pyrophosphate doped carbon (Fe2P2O7@C) was successfully synthesized for activation of peroxymonosulfate (PMS) for TC removal. The effects of Fe2P2O7@C dosage, PMS concentration, initial pH, initial TC concentration, and coexisting anions on TC degradation were investigated. The efficiency of TC removal in the Fe2P2O7@C/PMS system was improved to 89.8%, higher than PMS oxidation alone and adsorption of Fe2P2O7@C alone, indicating that Fe2P2O7@C can successfully activate PMS. The presence of NO3−, and SO42− slightly inhibited the removal of TC, while CO32− and HPO42− promoted the degradation of TC. The results of the cycling experiments showed that Fe2P2O7@C has good stability during the repeated activation of PMS. The results of scavenging experiments and electron paramagnetic resonance spectroscopy analysis identified the reactive oxygen species and demonstrated that free radical and non-free radical pathways play a synergistic role in this system, with the role of superoxide radicals and singlet oxygen dominating.