Synthesis of iron-based nanoparticles by green tea extract and their degradation of malachite

•Iron-based nanoparticles (Fe NPs) was synthesized using green tea extracts.•Fe–NPs were used for the degradation of malachite green.•The factors impacting on the degradation of malachite green were studied.•SEM, XRD and EDS were used for the characterization of Fe NPs. In this paper, green tea extract was used to synthesize iron nanoparticles (GT-Fe NPs) and degrade malachite green (MG) in aqueous solution. The results show that the damage to morphology and increase in size of GT-Fe NPs after reaction with MG were observed by SEM and EDS. XRD shows that there are few changes in the characteristic peaks of GT-Fe NPs before and after reaction. UV–vis spectroscopy shows that the absorption peak of MG decreased, while FTIR shows that the band at 1585cm−1 corresponded to the phenyl after reaction. The factors impacting on the removal efficiency of MG, including the initial solution pH, the initial concentration of MG, the dosage of GT-Fe NPs, and the reaction temperature, was also investigated. It emerged that 96% of MG was removed with a 50mg/L at 298K. Kinetics studies showed that the removal of MG fitted well to the pseudo first-order mode.