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

Abstract

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.