Porous carbon activated peroxydisulfate for rapid degradation of tetracycline: The key role of pyrolysis temperature

Carbon materials activated persulfate systems have gained growing interest for degrading emerging pollutants in wastewater, yet designing efficient metal-free carbon catalysts remains a challenge. Here, a novel metal-free porous carbon was prepared for the first time using sodium lignosulfonate (SL) as the raw material through a straightforward one-step pyrolysis process. This study investigates how pyrolysis temperature (600–800 °C) affects the structure of porous carbon and its performance to activate peroxydisulfate (PDS) for tetracycline (TC) degradation in an aqueous system. Results demonstrate that compared to those prepared at 600 and 700 °C, the porous carbon obtained at 800 °C (SL-800) exhibits a larger specific surface area (729.51 m²/g), higher graphitization, and greater electronic conductivity, all of which facilitate TC adsorption and PDS activation. Consequently, the SL-800/PDS system exhibits a high TC degradation rate (95.3 %), surpassing that of most previously reported biochar-based materials. The potential pathways and mechanisms governing TC degradation were elucidated using density functional theory (DFT) calculations, electron paramagnetic resonance (EPR), and liquid chromatography-mass spectrometry (LC-MS). Additionally, toxicity assessment software and mung bean cultivation demonstrate that the designed SL-800/PDS system can successfully diminish the ecological toxicity of TC. These findings yield valuable insights into developing non-metallic carbon materials that effectively activate PDS to remediate antibiotic-contaminated wastewater.