Co3O4-MnO2 nanoparticles moored on biochar as a catalyst for activation of peroxymonosulfate to efficiently degrade sulfonamide antibiotics

Co3O4-MnO2/BC, as an efficient activator of peroxymonosulfate (PMS) for the decomposition of soluble sulfonamide antibiotics, was successfully obtained via anchoring Co3O4-MnO2 nanoparticles on rice straw biochar (BC). The results demonstrated that 25 mg/L sulfadiazine (SDZ) could be thoroughly destructed by a combination of PMS (1 mM) and Co3O4-MnO2/BC (0.1 g/L) within 10 min. The pseudo-first-order rate constant (k) of the SDZ degradation was high up to 0.482 min−1, which was much larger than those reported in previous literature. The superior stability of the catalyst was confirmed through 5 recycle runs with approximately 100% degradation of SDZ and less than < 0.7 mg/L leached metal ions. Singlet oxygen (1O2) and sulfate radicals (SO4•−) were proved to be the principal reactive oxygen species (ROS) responsible for the degradation of SDZ. Combining the identification of ROS as well as intermediates during the SDZ degradation process, the possible catalytic mechanisms and the pathways of the SDZ degradation were deduced. The results further demonstrated that the combination of Co3O4-MnO2/BC and PMS also possessed a universal degradation capacity towards other typical organic pollutants, such as sulfisoxazole, sulfamethoxazole, bisphenol A and phenacetin. This is the first report on high-efficient heterogeneous activating PMS by Co3O4-MnO2/BC to eliminate soluble sulfonamide antibiotics, which makes it valuable for developing eco-friendly and efficient catalysts for the PMS activation.