Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India.
Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India.
J Environ Manage. 2020 Mar 15;258:110032. doi: 10.1016/j.jenvman.2019.110032. Epub 2020 Jan 7.
This study focuses on the photocatalytic degradation of quinoline, a recalcitrant heterocyclic nitrogenous aromatic organic compound, using the mixed oxide ZnO-TiO photo-catalyst. Photo-catalysts were synthesized by the solid-state reaction method at different calcination temperatures of 400 °C, 600 °C, and 800 °C. Different analytical methods, including Field emission scanning electron microscope, Brunauer-Emmett-Teller surface area, X-ray diffraction, UV-vis diffuse reflectance spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy analysis were used for the catalyst characterization. The highest pore surface area of 57.9 mg was obtained for the photo-catalyst calcined at 400 °C. The effects of calcination temperature, solution pH, initial concentration, catalyst dose as well as irradiation time were studied. At the optimum condition, i.e., calcination temperature of 400 °C, pH ≈8 and catalyst dose of 2.5 gL, maximum quinoline degradation and total organic carbon (TOC) removal efficiency of ≈92% and ≈78% were obtained after 240 min for initial quinoline amount of 50 mgL. The 1, 2 and n-order kinetic models were applied to analyze the quinoline degradation rate. The photocatalytic mechanism was studied by drawing energy level diagram with the help of the band-gap structures of the ZnO and TiO, potential of the free radicals like OH and O and HOMO-LUMO energy gap of the quinoline molecule. The proposed pathways of quinoline mineralization were suggested on the basis of the identified intermediates by the gas chromatograph-mass spectrometer analysis and scavenger study.
本研究采用混合氧化物 ZnO-TiO 光催化剂，聚焦于喹啉（一种难降解的杂环含氮芳香有机化合物）的光催化降解。光催化剂通过不同的煅烧温度（400°C、600°C 和 800°C）的固态反应法合成。采用场发射扫描电子显微镜、Brunauer-Emmett-Teller 比表面积、X 射线衍射、紫外-可见漫反射光谱、傅里叶变换红外光谱、拉曼光谱和 X 射线光电子能谱分析等多种分析方法对催化剂进行了表征。煅烧温度为 400°C 时，光催化剂的最高孔表面积为 57.9mg。考察了煅烧温度、溶液 pH 值、初始浓度、催化剂用量和辐照时间的影响。在最佳条件下，即煅烧温度为 400°C、pH 值≈8 和催化剂用量为 2.5gL，初始喹啉浓度为 50mgL 时，最大喹啉降解率和总有机碳（TOC）去除率分别达到 92%和 78%，反应时间为 240min。应用 1、2 和 n 级动力学模型分析了喹啉的降解速率。通过绘制 ZnO 和 TiO 的能带结构、自由基（如 OH 和 O）的势能以及喹啉分子的 HOMO-LUMO 能隙的能级图，研究了光催化机理。基于气相色谱-质谱分析和清除剂研究确定的中间产物，提出了喹啉矿化的可能途径。
