Huang Lanlan, Weng Xiulan, Chen Zuliang, Megharaj Mallavarapu, Naidu Ravendra
School of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, Fujian Province, China.
School of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, Fujian Province, China; Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of Environments, Mawson Lakes, SA 5095, Australia.
Spectrochim Acta A Mol Biomol Spectrosc. 2014 Sep 15;130:295-301. doi: 10.1016/j.saa.2014.04.037. Epub 2014 Apr 21.
Iron nanoparticles (Fe NPs) are often synthesized using sodium borohydride with aggregation, which is a high cost process and environmentally toxic. To address these issues, Fe NPs were synthesized using green methods based on tea extracts, including green, oolong and black teas. The best method for degrading malachite green (MG) was Fe NPs synthesized by green tea extracts because it contains a high concentration of caffeine/polyphenols which act as both reducing and capping agents in the synthesis of Fe NPs. These characteristics were confirmed by a scanning electron microscope (SEM), UV-visible (UV-vis) and specific surface area (BET). To understand the formation of Fe NPs using various tea extracts, the synthesized Fe NPs were characterized by SEM, X-ray energy-dispersive spectrometer (EDS), and X-ray diffraction (XRD). What emerged were different sizes and concentrations of Fe NPs being synthesized by tea extracts, leading to various degradations of MG. Furthermore, kinetics for the degradation of MG using these Fe NPs fitted well to the pseudo first-order reaction kinetics model with more than 20 kJ/mol activation energy, suggesting a chemically diffusion-controlled reaction. The degradation mechanism using these Fe NPs included adsorption of MG to Fe NPs, oxidation of iron, and cleaving the bond that was connected to the benzene ring.
铁纳米颗粒（Fe NPs）通常使用硼氢化钠合成，存在团聚现象，这是一个成本高且对环境有毒的过程。为了解决这些问题，基于茶提取物（包括绿茶、乌龙茶和红茶）采用绿色方法合成了Fe NPs。降解孔雀石绿（MG）的最佳方法是用绿茶提取物合成的Fe NPs，因为它含有高浓度的咖啡因/多酚，在Fe NPs的合成中既作为还原剂又作为封端剂。这些特性通过扫描电子显微镜（SEM）、紫外可见光谱（UV-vis）和比表面积（BET）得到了证实。为了了解使用各种茶提取物形成Fe NPs的情况，通过SEM、X射线能量色散光谱仪（EDS）和X射线衍射（XRD）对合成的Fe NPs进行了表征。结果发现，茶提取物合成的Fe NPs具有不同的尺寸和浓度，导致对MG的降解程度各异。此外，使用这些Fe NPs降解MG的动力学很好地符合伪一级反应动力学模型，活化能超过20 kJ/mol，表明这是一个化学扩散控制的反应。使用这些Fe NPs的降解机制包括MG吸附到Fe NPs上、铁的氧化以及切断与苯环相连的键。
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