A universal synthesis strategy for facile and scalable of magnetic biochar composite materials for PMS activation: catalytic mechanisms

Biochar-based catalysts have shown great promise for application in AOPs due to their wide source and good performance, while its development is limited by its complicated preparation process and large variation in performance. Herein, a series of magnetic biochar composites(Fe@NC-XX) based on different biomass (duckweed, shrimp shell, peanut shell, corncob, and pomelo peel) were fabricated via one-pot pyrolysis method. The removal of sulfadiazine (SDZ) by all materials reached more than 90% within 20min. The characterization results indicated that the special structure of Fe encapsulated in nitrogen-doped carbon nanotubes (CNTs) was the main reason why this approach is not limited to specific biomass. Acts as a catalytic center, Fe catalyzes the formation of CNTs during annealing. Meanwhile, graphene sheets and carbon nanoparticles formed by melamine and biomass decomposition migrate to the nucleus surface to form a hollow structure of CNTs. In addition, the results of quenching experiments and ESR tests elucidated that surface-bound radicals accumulated on the surface of CNTs, which can remarkably boost the efficient removal of SDZ. Consequently, the synthetic strategy of Fe nanoparticles anchored in N-doped CNTs that are not selective for biomass provides a new pathway for a universal synthesis method of biochar-based catalysts.