CeO2/NH2-MIL-88B(Fe) composites with peroxidase-like activity for colorimetric detection and photo-enzymatic synergetic degradation of ciprofloxacin hydrochloride

Abstract

Photocatalysis combined with enzyme catalysis for wastewater treatment is now a promising and challenging process. Therefore, it is necessary to synthesize a material with both photocatalytic and enzyme-catalyzed functions. CeO2/NH2-MIL-88B(Fe) composites with peroxidase-like activity (referred to as CNF-X, where X is the molar ratio of Ce to Fe) were prepared using a solvothermal method. The composites can be used for colorimetric detection, the limit of detection (LOD) was 0.029µM in the range of 50-200µM of ciprofloxacin hydrochloride (CIP). Using a combination of photocatalytic and enzymatic reactions, light excites enzyme activity to achieve highly efficient and selective chemical reactions. In addition, H2O2 activation promotes redox cycling reactions between Ce and Fe, providing more active sites and facilitating photo-enzymatic synergetic catalysis. Under the conditions of 0.01g CNF-5, pH = 3.5, and 25 °C, more than 92.8% of CIP (20mg/L solution) was degraded within 80min, and the photo-enzyme synergistic catalysis mechanism was examined. The stable enzymatic activity and good reusability of the material were confirmed by cycling experiments and X-ray diffraction (XRD) patterns before and after the reaction. The contribution ratio of radicals and non-radicals in the degradation of CIP was analyzed. Density functional theory (DFT) calculation was applied to predict possible degradation pathways. Simulation results stemmed from Toxicity Estimation Software Tool (T.E.S.T) showed an overall reduction in the toxicity of the intermediates. This study provides important application value and theoretical guidance for peroxidase-like materials in environmental detection and remediation.