Panda manure biochar-based green catalyst to remove organic pollutants by activating peroxymonosulfate: Important role of non-free radical pathways

Carbonaceous materials have emerged as promising metal-free catalysts to activate peroxymonosulfate (PMS) for the degradation of organic contaminants. In this study, a low-cost carbonaceous material panda manure biochar (PBC) was prepared by pyrolysis. The panda manure biochar showed excellent performance in the degradation reaction, and the removal efficiency of sulfamethazine (SMT), which was selected as a representative organic pollutant, exceeded 85% in 40 min. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) characterization confirmed that the improved catalytic performance was attributed to the oxygen-containing functional groups on the surface of the biochar. Radical quenching and electron paramagnetic resonance (EPR) experiments qualitatively demonstrated that O-1(2) played an important role in the degradation of SMT. Moreover, the non-radical process that dominated in the panda manure biochar/PMS system was proposed by cyclic voltammetry (CV) and linear sweep voltammetry (LSV) measurements. Sulfamethazine (SMT) was direct oxidized by the activated PMS where panda manure biochar acted as the electron transfer shuttle. The panda manure biochar /PMS system exhibited a high anti-interference ability to Cl-, HPO4-, HCO3-, SO42-, NO3-, and humic acid (HA) containing environments. This study provides a novel panda manure reuse process with high practicability, and proposes a reasonable degradation pathway for sulfamethazine (SMT) based on non-radical oxidation.