From aquatic biota to autogenous N-doping biochar—using a highly efficient nonradical dominant process for sulfamethoxazole degradation

Biochar has been considered as a promising environmental-friendly catalyst to activate peroxydisulfate (PDS) for contaminant degradation. In this study, a series of autogenous N-rich biochar derived from Spirulina were prepared by K2CO3 impregnation (NPSBs). The pyrolysis temperature and the rational design of morphology by K2CO3 had a significant influence on the performance of NPSBs to activate PDS. The NPSB-700 was capable of degrading 97.59% sulfamethoxazole (SMX) within 40 min because of the high surface area, high defect degree, and good electrical conductivity. The accelerated electron transfer and the generation of O-1(2) were elucidated to be the dominant pathways for SMX degradation. It has been proven that this is a process of reducing toxicity. Furthermore, NPSB-700 also showed excellent degradation performance to various pollutants. This study provides a facile modification strategy of Spirulina-based catalysts and deepens the comprehension of persulfate activation via nonradical oxidation.