title: Green synthesis of iron nanoparticles by various tea extracts: comparative study of the reactivity.
abstract: 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.
authors.affiliation: School of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, Fujian Province, China.
authors.forename: Lanlan
authors.initials: L
authors.lastname: Huang
authors.affiliation: School of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, Fujian Province, China.
authors.forename: Xiulan
authors.initials: X
authors.lastname: Weng
authors.affiliation: 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. Electronic address: Zuliang.chen@unisa.edu.au.
authors.forename: Zuliang
authors.initials: Z
authors.lastname: Chen
authors.affiliation: 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.
authors.forename: Mallavarapu
authors.initials: M
authors.lastname: Megharaj
authors.affiliation: 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.
authors.forename: Ravendra
authors.initials: R
authors.lastname: Naidu
mesh_terms: D000327:Adsorption; D001554:Benzene / Q000737:chemistry; D002110:Caffeine / Q000737:chemistry; D055772:Green Chemistry Technology; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D053768:Metal Nanoparticles / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D036103:Nanotechnology; D010100:Oxygen / Q000737:chemistry; D059808:Polyphenols / Q000737:chemistry; D012394:Rosaniline Dyes / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013662:Tea / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D059808:Polyphenols; D012394:Rosaniline Dyes; D013662:Tea; C005095:malachite green; D002110:Caffeine; D007501:Iron; D001554:Benzene; D010100:Oxygen
keywords: Characterization; Degradation; Fe NPs; Green synthesis; Malachite green