Spectral Characteristics of Hangjin2# Clay and Its Mechanism in Heterogeneous Fenton Reaction
LIU Zheng-jiang1, ZHANG Qian-cheng2, MA Hui-yan2*, LIU Ju-ming2
1. School of Light Industry and Textile, Inner Mongolia University of Technology, Huhhot 010080, China
2. School of Chemical Engineering, Inner Mongolia University of Technology, Huhhot 010051, China
Abstract：Hangjin2# clay is a layered iron-bearing natural mineral found in Ordos, Inner Mongolia. In succession，X-ray diffraction, pyridine adsorption Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to characterize Hangjin2# clay. X-ray photoelectron spectroscopy results indicated that Fe in Hangjin2# clay skeleton structure mainly exists as Fe(Ⅲ) and Fe(Ⅱ). Moreover, the binding energy of Si and Al in Hangjin2# clay has increased significantly compared with the standard binding energy of Si and Al in silicon-oxygen tetrahedron and octahedron aluminum oxygen, which indicated the presence of Lewis and Brönsted acid sites. In heterogeneous Fenton reaction, structural iron in Hangjin2# clay could react with H2O2 to produce?OH to degrade methyl orange, but the rate is slow and difficult to cycle. After acid activation, Si and Al’s increased binding energy in activated Hangjin2# clay has been confirmed, and iron in activated Hangjin2# clay has transformed into non-structural iron which coexists in the form of Fe2+ and Fe3+. Whatsmore, the increase Lewis acid and Brönsted acid sites on activated Hangjin2# clay surface have been confirmed by the characterization of X-ray photoelectron spectroscopy, pyridine infrared, and ammonia temperature-programmed desorption. After activation, Fe3+ and Fe2+ could circularly react with H2O2 to continuously generate ·OH to degrade methyl orange. Furthermore, Brönsted acid sites on the activated Hangjin2# clay surface could provide protons to surround H2O2, and the formation reaction of HO-2 will be inhibited. Lewis acid sites on activated Hangjin2# clay surface could increase adsorption oxygen content. Moreover, Fe2+ can be oxidized by adsorption oxygen to form Fe3+, promoting the circulation between Fe2+/Fe3+. Furthermore, in the oxidation process, the electron could transfer to adsorption oxygen to form O·-2 which can be reacted with protons provided by Brönsted acid sites to form ·OH. These ·OH and O·-2 are oxidizing radicals, which could improve the reaction activity of Hangjin2# clay in heterogeneous Fenton reactions. In addition, X-ray diffraction analysis indicated that acid activation could convert CO2-3to SO2-4, while SO2-4 has a less negative effect on Fenton reaction compared with CO2-3.
刘正江，张前程，马惠言，刘聚明. 杭锦2#土的光谱特征及非均相Fenton反应机理[J]. 光谱学与光谱分析, 2021, 41(11): 3512-3517.
LIU Zheng-jiang, ZHANG Qian-cheng, MA Hui-yan, LIU Ju-ming. Spectral Characteristics of Hangjin2# Clay and Its Mechanism in Heterogeneous Fenton Reaction. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2021, 41(11): 3512-3517.
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