Persulfate oxidation of norfloxacin by cobalt doped water hyacinth biochar composite: The key role of cobalt and singlet oxygen

The decay of active components and difficulty in separation and recovery are two major challenges for the use of biochar as a catalyst in the activation of persulfate (PS). In this study, cobalt loaded water hyacinth biochar (Co-BC) has been prepared and utilized in activation of PS for norfloxacin (NOR) degradation. Characterization results confirmed that cobalt mainly existed in the form of Co0 and Co3O4. The specific surface area of Co-BC was 349.00 m2/g, which was roughly 10 times greater than that of biochar (BC). NOR degradation experiment results showed that the Co-BC/PS system was able to remove 97.66 % of the NOR, which was nearly 1.57 times more efficient than that of BC/PS system. Electron paramagnetic resonance and free radical scavenging experiments illustrated that singlet oxygen(1O2) played the key role for NOR removal. The NOR removal mechanism revealed that Co played a crucial role for the activation of PS. Thus, Co-BC can serve as an eco-friendly catalyst for activating PS to efficiently eliminate antibiotics from water.