Application of a KOH-activated biochar for the activation of persulfate and the degradation of sulfamethoxazole
Résumé
In this work, valorized biomass was simultaneously pyrolyzed and activated with potassium hydroxide to produce a biochar with specific surface area of 1148 m2g−1, i.e. ten times greater than the pristine material, and significant amounts of surface oxygen species and carbonates, as evidenced by XRD and FTIR characterization. The activated biochar (50–250 mgL−1) was employed for a first time as sodium persulfate (100–750 mgL−1) activator to induce the adsorption/oxidation of sulfamethoxazole (SMX: 0.25–1.5 mgL−1), a representative emerging micropollutant, in various water matrices, including the detailed study of different parameters in wastewater. In general, the degradation follows pseudo-first order kinetic law and the apparent constant was found to increase with increasing biochar, persulfate concentration and acidity of the solution and decreasing with SMX concentration, matrix complexity (from surface water or ultrapure water to actual or simulated wastewater). The mechanism of oxidation is mainly through radical pathway and/or electron transfer, while singlet oxygen's contribution is inconsiderable, as evidenced by scavenging experiments and the structure of the various identified transformation products.