铜离子介导二氧化锰对甲基橙转化机制研究

Study on the Mechanism of Cu²⁺-Mediated Conversion of Methyl Orange by Manganese Dioxide

摘要: 众所周知，土壤环境中常见的锰氧化物对污染物的环境行为能够产生重要影响。但关于锰氧化物与重金属离子混合体系下，污染物的转化行为还不太清晰。因此，本研究探讨了环境中典型染料甲基橙在重金属铜离子(Cu²⁺)与二氧化锰(MnO₂)混合体系中的转化行为。首先利用X射线衍射仪(XRD)、高分辨扫描电镜仪(FESEM)和比表面积仪(BET)对制备的MnO2的晶型、表面形貌和比表面积等性质进行分析。随后，通过室内批次实验探讨了Cu²⁺和甲基橙含量以及反应溶液pH值等因素对反应体系中甲基橙的降解行为的影响。结果表明，总体上，Cu²⁺显著抑制了反应体系中甲基橙的去除效率；随着反应溶液pH值的降低，反应体系中甲基橙的抑制效率呈现出明显的下降趋势。此外，添加的Cu²⁺含量与反应体系中甲基橙的去除效率呈现显著的负相关；甲基橙含量的提升明显降低了甲基橙的抑制效率。分析证实，Cu²⁺与甲基橙结合MnO₂表面活性位点之间的竞争关系决定了反应体系中甲基橙的去除效率。因此，本研究对深入理解实际土壤环境中锰氧化物对染料类污染物环境行为具有重要理论意义和现实意义。

Abstract: As we all know, the common manganese oxides in the soil environment can have an important impact on the environmental behavior of pollutants. However, the transformation behavior of pollutants in the mixed system of manganese oxide and heavy metal ions is still unclear. Therefore, this study discussed the transformation behavior of methyl orange, a typical dye in the envi-ronment, in the mixed system of heavy metal copper ion (Cu²⁺) and manganese dioxide (MnO₂). Firstly, X-ray diffraction (XRD), high-resolution scanning electron microscopy (FESEM) and specific surface area meter (BET) were used to analyze the crystal form, surface morphology and specific surface area of the prepared MnO2. Then, the effects of Cu²⁺, methyl orange content and pH of the reaction solution on the degradation behavior of methyl orange in the reaction system were discussed through laboratory batch experiments. The results showed that overall, Cu²⁺ significantly inhibited the removal efficiency of methyl orange in the reaction system. With the decrease in the pH value of the reaction solution, the inhibition efficiency of methyl orange in the reaction system showed an obvious downward trend. In addition, the content of Cu²⁺ was negatively correlated with the removal efficiency of methyl orange in the reaction system. The increase in methyl orange content obviously reduces the inhibition efficiency of methyl orange. The analysis confirmed that the competitive relationship between Cu²⁺ and the surface active sites of methyl orange combined with MnO₂ determined the removal efficiency of methyl orange in the reaction system. Therefore, this study is of great theoretical and practical significance to deeply understand the environmental behavior of manganese oxides on dye pollutants in the actual soil environment.