Zhong De-Jian, Zhang Jian-Feng, Li Yao, Xie Xiao-Dan
Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
Huan Jing Ke Xue. 2019 Feb 8;40(2):701-707. doi: 10.13227/j.hjkx.201806091.
Chromium (Cr) contamination caused by industrial manufacturing poses a severe challenge in the environment. Titanium dioxide (TiO) has potential application in Cr removal due to its adsorption and photocatalytic performance. High-index TiO with exposed {201} facet was synthesized using the solvothermal method and characterized by SEM, TEM, XRD, and XPS. The adsorption of Cr(Ⅲ/Ⅵ) and photocatalytic reduction of Cr(Ⅵ) on TiO{201} was examined for the removal from water. The synthesized TiO{201} was constructed by a dandelion-like hierarchical structure. The adsorption isotherms of Cr(Ⅲ) and Cr(Ⅵ) on TiO{201} conformed to the Langmuir model, with maximum adsorption capacities of 22.7 mg·g and 13.2 mg·g, respectively. The best fitted results from the Freundlich model show that the adsorption of Cr(Ⅲ) and Cr(Ⅵ) on TiO{201} were favorable with the parameter of 1/ less than 0.5. The results of photocatalytic reduction show that TiO{201} can reduce Cr(Ⅵ) to Cr(Ⅲ) under UV irradiation, and Cr(Ⅲ) was further precipitated on the surface of TiO in the form of Cr(OH) and CrO, which was evidenced by XPS characterization. To explore the mechanism of photocatalytic reduction of Cr(Ⅵ), the effect of scavengers for photogenerated holes (EDTA-2Na) and electrons (KBrO) on Cr(Ⅵ) reduction was studied, and the results suggested that photogenerated electrons were the main reductant.
工业制造所导致的铬（Cr）污染给环境带来了严峻挑战。二氧化钛（TiO₂）因其吸附和光催化性能在去除铬方面具有潜在应用价值。采用溶剂热法合成了具有暴露{201}晶面的高指数TiO₂，并通过扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线衍射（XRD）和X射线光电子能谱（XPS）对其进行了表征。考察了TiO₂{201}对Cr(Ⅲ/Ⅵ)的吸附以及对Cr(Ⅵ)的光催化还原作用，以实现从水中去除铬。合成的TiO₂{201}由类似蒲公英的分级结构构成。Cr(Ⅲ)和Cr(Ⅵ)在TiO₂{201}上的吸附等温线符合朗缪尔模型，最大吸附容量分别为22.7 mg·g⁻¹和13.2 mg·g⁻¹。弗伦德利希模型的最佳拟合结果表明，Cr(Ⅲ)和Cr(Ⅵ)在TiO₂{201}上的吸附较为有利，1/n参数小于0.5。光催化还原结果表明，TiO₂{201}在紫外光照射下可将Cr(Ⅵ)还原为Cr(Ⅲ)，并且Cr(Ⅲ)以Cr(OH)₃和Cr₂O₃的形式进一步沉淀在TiO₂表面，XPS表征证实了这一点。为探究Cr(Ⅵ)光催化还原的机理，研究了光生空穴清除剂（EDTA-2Na）和电子清除剂（KBrO₃）对Cr(Ⅵ)还原的影响，结果表明光生电子是主要的还原剂。
