Efficient Activation of Peroxymonosulfate by Biochar-Loaded Zero-Valent Copper for Enrofloxacin Degradation: Singlet Oxygen-Dominated Oxidation Process

Simple Summary The misuse of antibiotics has caused ecological and human health risks on a global scale. Peroxymonosulfate can generate reactive oxygen species with extremely strong oxidative properties, which can degrade most types of antibiotics. For efficient removal of antibiotics in the aqueous environment, an economic biochar-loaded zero-valent copper was prepared by a simple pyrolysis method to activate peroxymonosulfate so that it can generate reactive oxygen species to oxidative and degrade the typical antibiotics, enrofloxacin. It was shown that complete degradation of enrofloxacin could be achieved within 30 min using biochar-loaded zero-valent copper to activate peroxymonosulfate, and the process of reactive oxygen species generation and the degradation pathway of enrofloxacin were also revealed. The removal of contaminants of emerging concern (CECs) has become a hot research topic in the field of environmental engineering in recent years. In this work, a simple pyrolysis method was designed to prepare a high-performance biochar-loaded zero-valent copper (CuC) material for the catalytic degradation of antibiotics ENR by PMS. The results showed that 10 mg/L of ENR was completely removed within 30 min at an initial pH of 3, CuC 0.3 g/L, and PMS 2 mmol/L. Further studies confirmed that the reactive oxygen species (ROS) involved in ENR degradation are center dot OH, SO4-center dot, O-1(2), and O-2(-). Among them, O-1(2) played a major role in degradation, whereas O-2(-)center dot played a key role in the indirect generation of O-1(2). On the one hand, CuC adsorbed and activated PMS to generate center dot OH, SO4-center dot and O-2(-)center dot. O-2(-)center dot was unstable and reacted rapidly with H2O and center dot OH to generate large amounts of O-1(2). On the other hand, both the self-decomposition of PMS and direct activation of PMS by C=O on biochar also generated O-1(2). Five byproducts were generated during degradation and eventually mineralized to CO2, H2O, NO3-, and F-. This study provides a facile strategy and new insights into the biochar-loaded zero-valent transition-metal-catalyzed PMS degradation of CECs.