Activation of peracetic acid by biochar for sulfamethoxazole degradation: Revealing roles of the active sites

Peracetic acid (PAA) based advanced oxidation processes are of increasing interest due to the generation of organic radical (R-O·) with strong oxidation ability. However, the mechanism of PAA activation by carbon materials is still worth further study. In this study, a series of chicken manure biochar (CBC) materials were prepared at different carbonization temperatures. The active sites and reaction mechanism of biochar materials were studied by the selective quenching method of functional groups. High carbonization temperatures endowed CBC with abundant microporous structure. In the SMX degradation experiment, the CBC material prepared at 900 °C (CBC900) allowed complete SMX degradation within 30 min. The degradation rate constant of SMX in the CBC900-activated PAA system was >13 times as high as that in the system activated by benchmark multi-walled carbon nanotubes. R-O· was identified as the dominant reactive specials in CBC900/PAA system and was produced via electron transfer between PAA and CBC900. The defect and oxygen-containing group -COOH was demonstrated as the key active sites to activate PAA. This study provides in-depth understanding of PAA activation by carbon materials and therefore makes contributions to the development and application of PAA-based AOPs.