Araei Zahra, Ghorbani Mohsen
Faculty of Chemical Engineering, Babol Noshirvani University of Technology, Shariati Ave, Babol, 47148-71167, Iran.
Sci Rep. 2025 Jul 2;15(1):22454. doi: 10.1038/s41598-025-07095-2.
Water supply and the removal of contaminants are critical challenges for modern societies. Various techniques have been developed to treat industrial wastewater. This study synthesized a Co3O4/CdAl2O4 nanocomposite using a hydrothermal method to remove Direct Blue and Basic Yellow organic dyes from aqueous media. The nanocomposite was characterized through FTIR, XRD, FESEM, EDX, TEM, PL, and UV-DRS spectroscopy to assess its physical, chemical, and optical properties, including morphology, particle size, crystalline structure, chemical composition, and band gap. DRS analysis revealed that the band gaps of CoO, CdAlO, and the synthesized nanocomposite were 1.5 eV, 3.66 eV, and 2.4 eV respectively. The formation of the heterogeneous CoO/CdAlO structure reduced the recombination rate compared to pure CoO and CdAlO samples. The study examined how operational parameters such as pH, contact time, initial dye concentration, and catalyst dosage affected dye removal efficiency. Optimal removal efficiency for Direct Blue was achieved at pH 2 and for Basic Yellow at pH 12 with a dye concentration of 10 ppm in a 20 mL solution using a catalyst dosage of 0.01 g. Maximum removal efficiencies were 91% for Direct Blue and 86% for Basic Yellow. Kinetic studies showed that the dye removal process followed pseudo-first-order kinetics indicative of a surface-controlled reaction. The experimental data fit well with this model, allowing calculation of the reaction rate constant and activation energy determination. The regression coefficients were 0.992 for Direct Blue and 0.991 for Basic Yellow with rate constants of 0.00379 s and 0.00125 s respectively. The photocatalytic regeneration results indicate that the synthesized nanocomposite demonstrates excellent reusability for up to four cycles, achieving final degradation rates of 80% and 74% for Direct Blue and Basic Yellow, respectively. Mechanistic studies reveal that superoxide radicals are the primary reactive species, serving as powerful oxidants that break down the chemical bonds of pollutant molecules. This process results in bond cleavage and ultimately mineralizes pollutants into simpler compounds like water and carbon dioxide. Consequently, the cobalt oxide/cadmium alumina nanocomposite, with its superior photocatalytic properties and high stability, shows significant potential for treating industrial wastewater containing organic dyes.
供水和去除污染物是现代社会面临的关键挑战。人们已经开发出各种技术来处理工业废水。本研究采用水热法合成了一种Co3O4/CdAl2O4纳米复合材料,用于从水介质中去除直接蓝和碱性黄有机染料。通过傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、能谱分析(EDX)、透射电子显微镜(TEM)、光致发光光谱(PL)和紫外可见漫反射光谱(UV-DRS)对该纳米复合材料进行了表征,以评估其物理、化学和光学性质,包括形态、粒径、晶体结构、化学成分和带隙。漫反射光谱分析表明,CoO、CdAlO和合成的纳米复合材料的带隙分别为1.5电子伏特、3.66电子伏特和2.4电子伏特。与纯CoO和CdAlO样品相比,异质CoO/CdAlO结构的形成降低了复合率。该研究考察了pH值、接触时间、初始染料浓度和催化剂用量等操作参数对染料去除效率的影响。在20毫升溶液中,使用0.01克催化剂用量,染料浓度为10 ppm时,直接蓝在pH值为2时达到最佳去除效率,碱性黄在pH值为12时达到最佳去除效率。直接蓝的最大去除效率为91%,碱性黄的最大去除效率为86%。动力学研究表明,染料去除过程遵循准一级动力学,表明是表面控制反应。实验数据与该模型拟合良好,从而可以计算反应速率常数并确定活化能。直接蓝的回归系数为0.992,碱性黄的回归系数为0.991,速率常数分别为0.00379 s和0.00125 s。光催化再生结果表明,合成的纳米复合材料在多达四个循环中表现出优异的可重复使用性,直接蓝和碱性黄的最终降解率分别达到80%和74%。机理研究表明,超氧自由基是主要的活性物种,作为强大的氧化剂分解污染物分子的化学键。这个过程导致键断裂,最终将污染物矿化为水和二氧化碳等更简单的化合物。因此,氧化钴/镉铝纳米复合材料具有优异的光催化性能和高稳定性,在处理含有机染料的工业废水方面显示出巨大潜力。
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