Efficient ciprofloxacin removal over Z-scheme ZIF-67/V-BiOIO3 heterojunctions: Insight into synergistic effect between adsorption and photocatalysis

To achieve remarkable synergy between adsorption and photocatalysis for the elimination of ciprofloxacin (CIP), ZIF-67/V-BiOIO3 (denoted as ZxVy) heterojunctions were successfully fabricated via the in-situ solvothermal method. In the as-prepared ZxVy heterojunctions, ZIF-67 with rhombic dodecahedron structure could adsorb and enrich CIP effectively due to its large specific area (1339.0 m2/g), π-π interactions, and high coordinating ability of Co2+ cations. The adsorption isotherm and kinetics of CIP on ZxVy heterojunctions can be depicted utilizing the Langmuir and pseudo-second-order models. The elimination of CIP over the ZxVy heterojunctions was studied by a synergy of adsorption and photocatalytic degradation process. And the optimum Z10V5 sample possessed the highest removal efficiency of 98.4%. Being compared with pristine ZIF-67 and V-BiOIO3, all the ZxVy heterojunctions exhibited superior photocatalytic performances for CIP degradation under illumination by visible light. The increased photocatalytic activity was primarily attributable to abundant surface-active sites, strong optical adsorption ability as well as the formed Z-scheme heterojunction between ZIF-67 and V-BiOIO3, which contributed to the acceleration of electron-hole pair separation and simultaneously retain high redox capacities. This work might provide some guidance of rational construction of MOFs-based Z-scheme heterojunctions for wastewater treatment via strong synergy between adsorption and photocatalysis.