Biochar-supported Co(OH)2 nanosheets activated persulfate: Enhanced removal of ciprofloxacin and membrane purification

Developing sophisticated composite based on biochar sheds light on the breakdown of antibiotics during wastewater treatment. In this work, the new cobalt species supported on wheat biochar catalyst (Co(OH)₂/biochar) nanofibers were created via a hydrothermal-electrospinning technique. A set of analyses revealed that the biochar's surface was covered by amorphous Co(OH)₂ nanosheets, which had a greater capacity to activate peroxymonosulfate (PMS) and break down ciprofloxacin (CIP) compared to Co(OH)₂. Specifically, the Co(OH)₂/biochar/PMS system achieved 1.30 min⁻¹ degradation rates, which is greater than pristine biochar and Co(OH)₂, and the excellent PMS activation was attributed to more exposing surface Co ions and faster Co²⁺/Co³⁺ cycling. Moreover, capture experiments and X-ray Photoelectron Spectrum (XPS) of the used catalyst further confirmed that the large amount of ¹O₂ produced in this system stems from the synergy between the activation of PMS by Co²⁺ and CO of biochar. Subsequently, a self-made wastewater nanofiber purification reactor was built to drive CIP removal, and the Co(OH)₂/biochar nanofiber maintained superior removal efficiency with continuous operation (8 h). Finally, the degradation pathway and toxicity estimation were further investigated. In all, this work provides a new nanofiber purification approach for the effective treatment of refractory antibiotics.