Non-metal activated peroxydisulfate by straw biochar for tetracycline hydrochloride oxidative degradation: catalytic activity and mechanism

In this study, stalk biochar (BC) was prepared by a high-temperature pyrolysis process and used as a non-metallic catalyst to activate peroxydisulfate (PDS) to degrade tetracycline hydrochloride (TCH). Various characterization results showed that BC had a hollow tubular structure, irregular folds, and important active sites such as oxygen-containing functional groups. Under the optimal reaction conditions, the degradation rate of TCH reached 98.1% within 120 min. In addition, the degradation performance was satisfactory and similar under acidic and near neutral pH, and higher temperature promoted the degradation of TCH. The SO4 center dot(-), center dot OH, and O-1(2) generated by PDS activation were reactive oxygen species (ROS), which degraded TCH through free radical/non-radical synergistic pathways. Quenching experiments proved that the generated SO4 center dot(-) and center dot OH might be the dominant reactive oxygen species (ROS) during the oxidative reaction. The research results will provide a theoretical basis for the application of PDS activated by non-metallic catalysts in the remediation of tetracycline antibiotics pollution.