Hasan Ibrahem M A, Tawfik Ahmed R, Assaf Fawzy H
Chemistry Department, Faculty of Science, South Valley University, Qena 83523, Egypt E-mail:
Water Sci Technol. 2022 Jan;85(2):664-684. doi: 10.2166/wst.2021.638.
Zinc oxide nanoparticles (ZnO NPs) were biosynthesized. According to gas chromatography/mass spectrometry analysis, chalcone, the main phytochemical, is probably complexed with Zn ions that are then oxidized to ZnO NPs by atmospheric O during heating. The ZnO NPs were characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller surface area analysis. Sphere-like ZnO NPs were formed with 11 nm mean crystallite size, 5.2 m g surface area, and 0.02 cm g total pore volume. The synthesized ZnO showed excellent photocatalytic degradation (96.5±0.24% in 1 hour at 25 °C) of malachite green (MG) in aqueous solutions under ultraviolet light at optimum conditions; pH 10, MG initial concentration of 20 mg L, and ZnO dose of 1.5 g L. Also, ZnO showed very good reusability (92.9± 0.2% after five runs). The experimental data obeyed pseudo-first-order kinetics (R = 0.92). The photocatalysis process was dependent on the following species in the order: OH > electron/positive hole pairs > O. Moreover, photodegradation efficiency decreased in the presence of CO, HCO, and Cl, but increased in the presence of NO and SO ions. Thus, the green synthesized ZnO NPs can be applied as an efficient photocatalyst for the removal of MG from aqueous media.
氧化锌纳米颗粒（ZnO NPs）通过生物合成得到。根据气相色谱/质谱分析，主要植物化学成分查尔酮可能与锌离子络合，然后在加热过程中被大气中的氧气氧化为ZnO NPs。通过热重分析、傅里叶变换红外光谱、X射线衍射、场发射扫描电子显微镜、透射电子显微镜、能量色散X射线光谱和布鲁诺尔-埃米特-泰勒表面积分析对ZnO NPs进行了表征。形成了球状ZnO NPs，平均微晶尺寸为11 nm，表面积为5.2 m²/g，总孔体积为0.02 cm³/g。在最佳条件下（pH 10、孔雀石绿（MG）初始浓度为20 mg/L、ZnO剂量为1.5 g/L），合成的ZnO在紫外光下对水溶液中的孔雀石绿（MG）表现出优异的光催化降解性能（25℃下1小时内降解率为96.5±0.24%）。此外，ZnO表现出非常好的可重复使用性（五次循环后为92.9±0.2%）。实验数据符合准一级动力学（R² = 0.92）。光催化过程对以下物种的依赖性顺序为：·OH＞电子/空穴对＞O₂。此外，在CO₃²⁻、HCO₃⁻和Cl⁻存在下光降解效率降低，但在NO₃⁻和SO₄²⁻离子存在下光降解效率增加。因此，绿色合成的ZnO NPs可作为一种高效的光催化剂用于从水介质中去除MG。
