Spinel ferrites with magnetic properties have great potential for the decontamination of aqueous systems due to their ease of recycling by magnetic separation. Herein, the purpose is to enhance ZnFe2O4 spinel properties in terms of magnetization and catalytic performance via Mn substitution into the crystal structure. Zn1−xMnxFe2O4 (x = 0–1) nanoclusters were successfully synthesized via an optimal hydrothermal process, in which additives (i.e., citric acid and ammonia) play key roles in inhibiting impurity phase formation via homogenizing the distribution of metal ions and slowing down the reaction rate. At a Zn/Mn ratio of 1 : 3, the nanocluster Zn0.25Mn0.75Fe2O4 (ZMF0.75) composed of nanoparticles with sizes ranging from 5 to 10 nm shows the highest saturation magnetization (Ms = 68 emu g−1, which is ∼5 times greater than that of ZnFe2O4) and the best catalytic performance, with >99% azoxystrobin (AZX) degradation in a Fenton-like system. Moreover, the findings unveiled that the balance of Zn and Fe occupation in the polyhedron centres in the spinel crystal is broken upon replacing Zn with Mn. In all probability, the Zn/Fe/Mn cross-occupation phenomenon is essential for enhancing the activity of Fe and Mn multivalent metal atoms. A plausible mechanism for the synergistic effect of multiple active sites in ZMF0.75 on the formation of HO˙ and HO2˙ radicals is proposed. This work proves that Mn-substituted ZnFe2O4 could be an efficient heterogeneous Fenton-like catalyst for EOC decontamination in aqueous systems with ease for recycling via magnetic separation.
Based on the size and surface properties of dimethomorph and flumorph, we used a computer simulation-assisted size exclusion hapten design strategy to develop group-specific monoclonal antibodies that can simultaneously recognize dimethomorph and flumorph. For this, we performed quantitative and visual semi-quantitative time-resolved fluorescence immunochromatography (TRFICA) to simultaneously detect dimethomorph and flumorph in potatoes and apples. In potato samples, the visual limit of detection (vLOD) for dimethomorph and flumorph was 4 ng/mL and 8 ng/mL, respectively, whereas the quantitative limit of detection (qLOD) for dimethomorph and flumorph was 0.26 and 0.33 ng/mL, respectively. The vLOD of dimethomorph and flumorph in apple samples was 8 ng/mL, whereas the qLOD of dimethomorph and flumorph was 0.17 and 0.38 ng/mL, respectively. The average recovery of potato and apple samples ranged from 77.5% to 121.7%, which indicated that the method can be used to rapidly detect dimethomorph and flumorph in food samples.
危险品化学品经营许可证（带存储）