Lin Jiajiang, Sun Mengqiang, Liu Xinwen, Chen Zuliang
Postdoctoral Programme in Chemistry, Fujian Normal University, Fuzhou, Fujian, 350007, China; Fujian Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Fujian Normal University, Fuzhou, 350007, China.
Fujian Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Fujian Normal University, Fuzhou, 350007, China.
Chemosphere. 2017 Oct;184:664-672. doi: 10.1016/j.chemosphere.2017.06.038. Epub 2017 Jun 12.
Kaolin supported nanoscale zero-valent iron (K-nZVI) is synthesized and applied as the Fenton-like oxidation catalyst to degrade a model azo dye, Direct Black G (DBG). The characterization of K-nZVI by the high resolution transmission electronmicroscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Energy Diffraction Spectrum (EDS) and X-ray diffraction (XRD) show that kaolin as a support material not only reduces the aggregation of zero-valent iron (nZVI) but also facilitates the Fenton-like oxidation by increasing the local concentration of DBG in the vicinity of nZVI. Pseudo first-order and pseudo second-order kinetic models are employed to reveal the adsorption and degradation of the DBG using K-nZVI as the catalyst. A better fit with pseudo second-order model for the adsorption process and equal excellent fits with pseudo first-order and pseudo second-order models for the degradation process are observed; the adsorption process is found to be the rate limiting step for overall reactions. The adsorption, evaluated by isotherms and thermodynamic parameters is a spontaneous and endothermic process. High-performance liquid chromatography-mass spectrometry (LC-MS) analysis was used to test degraded products in the degradation of DGB by K-nZVI. A removal mechanism based on the adsorption and degradation is proposed, including (i) prompt adsorption of DBG onto the K-nZVI surface, and (ii) oxidation of DBG by hydroxyl radicals at the K-nZVI surface. The application of K-nZVI to treat real wastewater containing azo dyes shows excellent degradation efficiency.
合成了高岭土负载的纳米级零价铁（K-nZVI），并将其用作类芬顿氧化催化剂来降解一种偶氮染料模型——直接黑G（DBG）。通过高分辨率透射电子显微镜（HRTEM）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）、能量衍射光谱（EDS）和X射线衍射（XRD）对K-nZVI进行表征，结果表明，高岭土作为载体材料不仅减少了零价铁（nZVI）的聚集，还通过提高nZVI附近DBG的局部浓度促进了类芬顿氧化。采用伪一级和伪二级动力学模型来揭示以K-nZVI为催化剂时DBG的吸附和降解情况。观察到吸附过程与伪二级模型拟合较好，降解过程与伪一级和伪二级模型拟合效果同样出色；吸附过程被发现是整体反应的速率限制步骤。通过等温线和热力学参数评估的吸附是一个自发的吸热过程。使用高效液相色谱-质谱联用（LC-MS）分析来检测K-nZVI降解DBG过程中的降解产物。提出了一种基于吸附和降解的去除机制，包括（i）DBG迅速吸附到K-nZVI表面，以及（ii）DBG在K-nZVI表面被羟基自由基氧化。将K-nZVI应用于处理含偶氮染料的实际废水显示出优异的降解效率。
