Synthesis of N-doped porous biochar from chemical pollutant for efficient sulfadiazine degradation: Performance, mechanism and bio-toxicity assessment

Turning chemical wastes into valuable materials presently is a key challenge. Therefore, a facile method was employed upon synthesis of an N-doped porous biochar (NPBC) catalyst via pyrolysis of chemical pollutant (reactive red 2, RR2), urea, and NaHCO3. Using NaHCO3 activation, the NPBC/PMS system exhibited excellent catalytic efficiency for sulfadiazine (SDZ) degradation, which was attributed to the porous structure with abundant active species of graphitic C/N, C=O, –COOH, and C–S–C. Significantly, the NPBC displayed excellent environmental suitability, catalytic universality for the decomposition of common organic pollutants (i.e. bisphenol A, ciprofloxacin, tetracycline, and sulfamethoxazole) and catalytic recycling stability. In addition, free radical quenching and mechanism inspection demonstrated that 1O2 is the dominating reactive oxygen species (ROS) in the NPBC/PMS system. The most probable degradation pathway and mechanism are proposed. Finally, the biotoxicity of SDZ before and after degradation was evaluated by ECOSAR analysis and the germination tests of wheat seeds. This study not only provides a rational method for the facile synthesis of valuable materials from chemical pollutants, but also presents a direction for discovering metal-free catalysts with remarkable activity for water decontamination in the future.