Peroxydisulfate activation by digestate-derived biochar for azo dye degradation: Mechanism and performance

Peroxydisulfate (PDS) is a low-cost sulfate radical-based oxidant, and carbonaceous material is perceived as efficient and environmentally friendly catalyst for PDS activation. Herein, biochar derived from food waste digestate (FWDB) was prepared, which exhibited excellent potential for removing contaminant due to its unique characteristics. The performance of FWDB for PDS activation was evaluated via the removal of a typical azo dye of reactive brilliant red X-3B, and the mechanism was explored. Under the conditions of FWDB dosage of 0.5 g/L, PDS concentration of 1.5 mM, no adjusting of pH value, and 25 degrees C, 92.21% of X-3B (initial concentration of 1 g/ L) in the solution was removed within 30 min. SO4'-, 'OH, O2'-, and 1O2 were identified as the reactive oxygen species (ROS) in this FWDB/PDS system, and the graphitized carbon, doped-N, oxygen-containing groups, and defective sites on the surface of FWDB were answerable for the generation of ROS. The obtained results confirmed the application potential of FWDB in the treatment of organic wastewater, providing an alternative strategy of "treating waste with waste".