Iron-modified biochar enhanced the activation of peracetic acid for removal of imidacloprid: efficiency, active species and catalytic mechanism

Imidacloprid (IMI) is a highly toxic organic pollutant. Therefore, effective IMI treatment methods must be developed. This study synthesized iron-modified rape straw biochar (Fe-RSB) to activate peracetic acid (PAA) for IMI removal from water. At the optimal concentrations of 0.55 g∙L − 1 for Fe-RSB and 0.25 mM for PAA, the removal of IMI reached 81.6% after 60 min. Additionally, the IMI removal was minimally affected over a broad pH range (3–11). CH 3 C(O)O· and CH 3 C(O)OO· played crucial roles in the IMI degradation. The degradation pathway of IMI consisted of three pathways, and the ecological hazards of most intermediates were lower than those of IMI. The effect of Cl⁻ on IMI removal was concentration dependent, 2 mM Cl⁻ showed slight inhibition, while 10 mM Cl⁻ promoted the degradation. In contrast, both HA and HCO 3 ⁻ exhibited inhibitory effects across the tested concentration ranges. After five cycles, the removal of IMI reached 61.9%, indicating the stability of Fe-RSB. Overall, a new Fe-RSB/PAA process is proposed for the degradation of IMI.