Green Synthesis Of Iron Nanoparticales Using Medicago Sativa L.for Removal Of Lead,Uranium And Chromium In Waste Water

In recent years,the discovery of plant reduction preparation of nano-iron is still in its infancy.Therefore,choosing biomass accurately,analyzing its role in the material and its reaction mechanism,regulating the size of nanoparticles and improving the synthesis ability,which are researching directions of applying nanoparticles to remove heavy metals in the waste water.In this study,The optimal conditions for the synthesis of green iron nanoparticles（ML-FeNPs）by reduction of（Fe（Ⅱ）、Fe（ⅡI））by Medicago sativa L.were studied,ML-FeNPs was analyzed by UV-Vis,XRD,SEM,TEM,FTIR and EDX techniques,and the removal effects of Pb（Ⅱ）,U（Ⅵ）and Cr（Ⅵ）in aqueous solution and the plausible mechanism in the different condition were studied.Draw the following main conclusions:（1）The prepared ML-FeNPs are amorphous ellipsoid particle with particle size of 70⁸0 nm,and contain Fe₂O₃,Fe₃O₄,FeOOH and Fe⁰.In addition,ML-FeNPs are encapsulated by the organic groups of O-H,CH₂,C-H,C=C,C-N,C-O-C.（2）The optimum removal conditions are as follows:an initial Pb（Ⅱ）concentration of 20 mg/L,temperature of 25℃,pH of 4,reaction time of1.5 hours,At this condition,the removal rates of Pb（Ⅱ）achieved 95.48%by ML-FeNPs.Initial U（Ⅵ）concentration of 10 mg/L,temperature of25℃,p H of 6,reaction time of 1.5 hours,dosing ratio of ML-FeNPs and U（Ⅵ）of 12.5 mg/mL.At this condition,the removal rates of U（Ⅵ）achieved 88.90%by ML-FeNPs.Initial Cr（Ⅵ）concentration of 10 mg/L,temperature of 25℃,pH of 4,reaction time of 1.5 hours.the reductive removal rates of Cr（Ⅵ）can achieved 95.21%;the fixed removal rates of Cr（Ⅵ）reached 61.1%.（3）ML-FeNPs removed Pb（Ⅱ）,U（Ⅵ）and Cr（Ⅵ）mainly takes place in its surface,the plausible mechanism for the removal them using ML-FeNPs is the combined action of reduction,adsorption,complexation,and flocculation.C-N group and Fe-O bond played a major role in the removal of Pb（Ⅱ）,U（Ⅵ）and Cr（Ⅵ）by ML-FeNPs and the removal of Pb（Ⅱ）,U（Ⅵ）and Cr（Ⅵ）is improved by the organic groups.