摘要/Abstract

系统研究了ZVI(零价铁粉)-Fenton体系协同去除铜离子和亚甲基蓝(MB)污染物过程中, ZVI微表面发生的化学转化以及目标污染物降解机理. 分别利用扫描电子显微镜(SEM), X射线能谱(EDS), X射线衍射(XRD), X射线光电子能谱(XPS)和傅里叶变换红外光谱(FTIR)等技术, 对比分析了反应前后以及不同体系之间ZVI表面结构, Fe和Cu化学转移的变化. 结果表明, 在ZVI/H₂O₂体系中反应后ZVI表面腐蚀产物较多, 主要为Fe₃O₄和Fe₂O₃. 在ZVI/H₂O₂-Cu体系中, 虽ZVI腐蚀作用更加剧烈, 但ZVI表面残留的腐蚀产物较少, 且腐蚀产物中Fe₃O₄含量的占比增加. Cu ²⁺主要还原产物为Cu ⁰, 同时还伴随着CuO的生成. pH影响实验表明, ZVI/H₂O₂-Cu体系不仅强化了MB的降解, 有效地去除了总溶解铜离子(TCu), 同时还扩大ZVI-Fenton体系的有效pH范围(pH=2.5~5.5). 叔丁醇捕获自由基实验表明, 羟基自由基是氧化降解MB的主要活性物质. 最后针对ZVI-Fenton体系协同去除复合双目标污染物的机理进行研究分析.
关键词: 零价铁粉, 非均相芬顿, 循环催化, 协同作用, 微表面转化
The chemical transformation of ZVI micro-surface and the degradation mechanism in the process of synergistic removal of copper ions and methylene blue pollutants by ZVI-Fenton system were studied systematically. The samples of ZVI, before and after reaction in the ZVI/H₂O₂ and ZVI/H₂O₂-Cu systems, were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS) and Fourier Transform infrared spectroscopy (FTIR) to research the changes of ZVI surface structure, Fe and Cu species’ chemical conversion. The results showed that the residual corrosion products on the surface of ZVI were more and the corrosion products were mainly Fe₃O₄ and Fe₂O₃ after reaction in the ZVI/H₂O₂ system. However, in the ZVI/H₂O₂-Cu system, the corrosion effect of ZVI was more significant, but the residual corrosion products of ZVI surface were less, and the proportion of Fe₃O₄ increased. In addition, the main reduction product of Cu ²⁺ was Cu ⁰, which was accompanied by the generation of CuO. Furthermore, the effects of pH on the removal of pollutants from the five systems (ZVI, ZVI-Cu, H₂O₂-Cu, ZVI/H₂O₂ and ZVI/H₂O₂-Cu) were compared and the changes in TCu and TFe concentrations under different pH conditions were monitored. The results indicated that the ZVI/H₂O₂-Cu system not only simultaneous effectively remove MB and TCu compared with other three systems, but also enlarged the effective pH range (pH=2.5~5.5) of ZVI-Fenton system. In addition, free radical capture experiments showed that hydroxyl radicals played an important role in the oxidative degradation of methylene blue, and 10 mmol/L tert-butanol could completely capture hydroxyl radicals in the system. Finally, the mechanism of synergistic removal of TCu and MB degradation by ZVI-Fenton system was revealed. The substitution reaction between ZVI and Cu ²⁺, the action of Cu ⁰ and ZVI galvanic cells, the acid corrosion effect, and the redox cycle of iron and copper together accelerate the degradation of MB by the system and promote the conversion of ZVI surface substances. This study provides a theoretical basis for collaborative treatment of industrial complex pollutants.
Key words: zero-valent iron powder, heterogeneous Fenton, cyclic catalysis, synergism, micro surface transformation


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