Institute of Applied Technology and Sustainable Development, Nguyen Tat Thanh University, 298-300A Nguyen Tat Thanh, District 4, Ho Chi Minh City 755414, Viet Nam; NTT Hi-Tech Institute, Nguyen Tat Thanh University, 298-300A Nguyen Tat Thanh, District 4, Ho Chi Minh City 755414, Viet Nam.
Department of Chemical Engineering, Sri Sivasubramaniya Nadar College of Engineering, Chennai 603110, India.
Environ Res. 2022 Nov;214(Pt 2):113925. doi: 10.1016/j.envres.2022.113925. Epub 2022 Jul 19.
The pollution of organic dyes such as malachite green is one of the globally critical issues, calling for efficient mitigation methods. Herein, we developed green MnO nanoparticles synthesized using natural compounds extracted from Costus woodsonii flowers under an ultrasound-assisted mode. The materials were characterized using several physicochemical techniques such as Fourier-transform infrared spectroscopy, X-ray diffraction, Energy-dispersive X-ray spectroscopy, scanning electron microscopy, Raman spectroscopy, and N adsorption desorption isotherm measurement. The X-ray diffraction and N isotherm plots confirmed the presence of tetragonal γ-MnO phase and mesoporous structure, respectively. Carbonyl groups derived from flavonoids or carboxylic compounds were found in the surface of green MnO nanoparticles. The effect of pH, contact time, dose, and concentration on the adsorption of malachite green over green MnO was carried out. The maximum malachite green adsorption capacity for green MnO nanoparticles was 101-162 mg g. Moreover, kinetic and isotherm adsorption of malachite green obeyed Langmuir (R = 0.980-0.995) and pseudo first-order models (R = 0.996-1.00), respectively. Adsorption of malachite green over green MnO was a thermodynamically spontaneous process due to negative Gibbs free energy values (ΔG < 0). Green MnO nanoparticles offered a high stability through the FR-IR spectra analysis. With a good recyclability of 4 cycles, green MnO nanoparticles can be used as potential adsorbent for removing malachite green dye from water.
孔雀石绿等有机染料的污染是全球面临的重大问题之一，需要寻求有效的缓解方法。在此，我们采用超声辅助模式，利用从Costus woodsonii 花朵中提取的天然化合物合成了绿色 MnO 纳米粒子。通过傅里叶变换红外光谱、X 射线衍射、能量色散 X 射线能谱、扫描电子显微镜、拉曼光谱和 N 吸附脱附等温线测量等多种物理化学技术对材料进行了表征。X 射线衍射和 N 等温线图分别证实了四方γ-MnO 相和中孔结构的存在。在绿色 MnO 纳米粒子的表面发现了源自类黄酮或羧酸化合物的羰基。研究了 pH、接触时间、剂量和浓度对绿色 MnO 吸附孔雀石绿的影响。绿色 MnO 纳米粒子对孔雀石绿的最大吸附容量为 101-162mg g。此外，孔雀石绿的动力学和等温吸附均遵循 Langmuir（R=0.980-0.995）和拟一级模型（R=0.996-1.00）。由于负的吉布斯自由能值（ΔG<0），孔雀石绿在绿色 MnO 上的吸附是一个热力学自发过程。通过 FR-IR 光谱分析，绿色 MnO 纳米粒子具有较高的稳定性。经过 4 次循环的良好回收性，绿色 MnO 纳米粒子可用作从水中去除孔雀石绿染料的潜在吸附剂。
