Double template synthesis of N/S co-doped shrimp shell derived biochar for efficient sulfadiazine degradation: The role of non-radical pathway

In this work, waste shrimp shells were used to synthesize N/S-co-doped biochar nanomaterials (BC-NS) by simple hard template and soft template. Through the cooperative effect of adsorption and degradation, the BC-NS/PMS system could remove 100 % of SDZ within 30 min. The combination of soft and hard templates produces hierarchical porous structure and provides more reactive sites. The radical quenching tests and electron paramagnetic resonance measurements (EPR) illustrated that the non-radical 1O2 was the dominant reactive oxidative species (ROS) in the BC-NS/PMS system. By density functional theory (DFT) computation, it demonstrated that graphitic N and pyridinic N were the main reactive sites of BC-NS. Finally, intermediate products of SDZ have been identified and four possible pathways for the degradation of SDZ were proposed. Consequently, a novel synthesis strategy of metal-free biochar materials was proposed in this study, which broadened a new prospect for the application of metal-free biochar materials in SR-AOPs.