In situ synthesis of flower-structured ZnO@YFC for the efficient piezocatalytic degradation of tetracycline wastewater: Degradation mechanism and toxicity evolution

• A novel biochar based ZnO@YFC-4 piezo-catalyst with high activity was prepared. • 89.04% TC was degraded in 20 min. • OH and O 2 − were turned out to be the main radicals for TC degradation. • Three degradation pathways of TC were proposed and the toxicity of its intermediate was evaluation. • ZnO@YFC piezo-catalytic system showed durable activity and good stability towards interference. Antibiotic wastewater has attracted significant attention in recent years. In this study, a novel biochar-based piezocatalyst with a nanoflower structure was synthesized using a method involving the in situ growth of ZnO on a Yang flocculant. The piezoelectric degradation rate of tetracycline was 89.07% after 20 min, and the first-order kinetic constant was 0.682 min −1 . Density functional theory calculations showed that the high catalytic activity of ZnO@YCF resulted from its excellent electron transport ability. Radical quenching and electron paramagnetic resonance results showed that OH and O 2 − radicals were the main radicals involved in TC degradation, with contributions of 58.78% and 37.39%, respectively. A possible TC degradation pathway was proposed based on intermediate studies. Moreover, aquatic toxicity migration was evaluated during the TC degradation process using an ecological structure–activity relationship model. This study proposes a new concept and an efficient way to reuse biomass waste.