This study reported the synthesis and evaluation of mixed metal oxides MgO/Al₂O₃–TiO₂ and ZnO/Al₂O₃–TiO₂ as heterogeneous photocatalysts for the potential degradation of a mixture of organic dyes such as methylene blue and methyl orange. First, hydrotalcites were synthesized by two different methods (conventional and microwave); then they were treated at 500 °C to obtain the corresponding Mg/Al–Ti and Zn/Al–Ti mixed metal oxides. The Layered Double Hydroxide (LDH) and the Mixed Metal Oxides were characterized by N₂ adsorption–desorption, X-ray Diffraction, Fourier transform infrared, X-Ray photoelectron Spectrometry and Scanning Electron Microscopy. The degradation processes of the dyes were carried out under ultraviolet light irradiation and absorbance readings were compared using a UV–vis spectrometer. The ensuing degradation of products was corroborated through a mass spectrometry analysis. According to the photodegradation efficiency of dyes under UV irradiation, the activity of the samples showed the following order: ZnAlTiM > ZnAlTiC > MgAlTiC > MgAlTiM. The improvement in the activity of ZnAlTiM may be attributed to its lowest reflectance and highest degree of UV light absorbance, its smallest valence band and its ZnO-support interaction. Degradations of 25% and 68% were achieved for methyl orange and methylene blue, respectively, after 120 min of reaction. The degradation process conforms to the Langmuir–Hinshelwood type kinetic model.

Graphic Abstract

中文翻译：

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MgAlTi和ZnAlTi混合氧化物光催化降解水合染料

这项研究报告了混合金属氧化物MgO / Al ₂ O ₃ -TiO ₂和ZnO / Al ₂ O ₃ -TiO ₂作为非均相光催化剂的合成和评价，这些光催化剂可降解亚甲基蓝和甲基橙等有机染料的混合物。首先，通过两种不同的方法（常规方法和微波方法）合成水滑石。然后在500°C下进行处理，以获得相应的Mg / Al-Ti和Zn / Al-Ti混合金属氧化物。层状双氢氧化物（LDH）和混合金属氧化物的特征在于N ₂吸附-解吸，X射线衍射，傅立叶变换红外，X射线光电子能谱和扫描电子显微镜。染料的降解过程在紫外线照射下进行，使用紫外可见光谱仪比较吸光度读数。通过质谱分析证实了产物随后的降解。根据染料在紫外线照射下的光降解效率，样品的活性表现为以下顺序：ZnAlTiM> ZnAlTiC> MgAlTiC> MgAlTiM。ZnAlTiM活性的提高可能归因于其最低的反射率和最高的紫外光吸收度，其最小的价带和其ZnO-载体相互作用。甲基橙和亚甲基蓝的降解分别达到25％和68％，反应120分钟后。降解过程符合Langmuir-Hinshelwood型动力学模型。

图形摘要