Green Preparation Of Nano-iron And Its Removal Of U(?) And Pb(?)

Utilization of uranium and lead often produces a large amount of wastewater,which will endanger human health after entering the natural environment.herefore,how to deal with uranium and lead-containing wastewater quickly,efficiently and environmentally has become an urgent problem.In this paper,the green nZVI was first prepared by reducing sunflower extract,and then the carbon nanotube-green nanoiron composite?N-Fe/CNT?and sunflower disk powder-green nano were prepared by compounding nZVI with carbon nanotubes and sunflower disk powder,respectively.Iron composite material?N-Fe/SFP?.Then,N-Fe/CNT and N-Fe/SFP were used in the laboratory to simulate the treatment and utilization of uranium and lead-containing wastewater,and the factors of anion and cation,pH,material dosage,temperature,reaction time and other factors were studied.Influence on the removal of U?VI?and Pb???wastewater from composite materials,determine the best reaction conditions;use thermodynamic and kinetic models to fit and analyze the experiment;Use scanning electron microscope?SEM?,X-ray energy spectrometer?EDS?,Fourier Infrared Spectroscopy?FTIR?and other technical methods were used to characterize the samples before and after the reaction,and to analyze the removal mechanism of the test.The test results are as follows:The removal test of U?VI?by N-Fe/CNT showed that at a temperature of 40?,pH=5,an initial concentration of U?VI?of 10 mg/L,a dosage of 4 g/L,and a reaction of 150 min,The removal rate of U?VI?by N-Fe/CNT can reach 92.1%;The anions and cations Ca²⁺,Mg²⁺,Ba²⁺,Cu²⁺,SO₄^2-,Cl^-,etc.All have an inhibitory effect on the removal of U?VI?by N-Fe/CNT.The concentration was large and enhanced,mainly due to occupying the N-Fe/CNT reaction site and forming[UO₂?CO₃?₂]^2-and other complexes with UO₂²⁺,affects removal of U?VI?.Isothermal adsorption model research shows that Langmuir's isothermal adsorption equation can better describe the adsorption process of U?VI?by N-Fe/CNT;Thermodynamic research shows that the adsorption of U?VI?by N-Fe/CNT is an endothermic and spontaneous process;The quasi-second-order kinetic model is more suitable for describing the adsorption behavior of U?VI?by N-Fe/CNT,and the chemical adsorption is the main one.From the characterization analysis,it can be seen that the surface of N-Fe/CNT has a hollow network structure.After the reaction,the surface of N-Fe/CNT is covered with dense matter and becomes flat and dense.The change is obvious.-OH and C=O in N-Fe/CNT plays a major role,and the removal of U?VI?by N-Fe/CNT is mainly based on the adsorption,redox and complex reactions.The removal test of Pb???by N-Fe/CNT showed that at a temperature of 20?,pH=6,initial concentration of U?VI?50 mg/L,and reaction for 120 min,N-Fe/CNT on Pb???The removal rate can reach94.7%,the maximum adsorption capacity Q_max=15.02 mg/g;The coexistence of anions and cations Ca²⁺,Mg²⁺,SO₄^2-,and CO₃^2-can all inhibit the removal of Pb???by N-Fe/CNT,The main reason is that the anions and cations will occupy the reaction site of N-Fe/CNT,and generate a part of the precipitate wrapped around N-Fe/CNT,thereby affecting the removal of Pb???;Isothermal adsorption model studies show that Freundlich's isothermal adsorption equation can better describe the adsorption process of Pb???by N-Fe/CNT,indicating that the reaction is multilayered,not monolayer adsorption;Thermodynamic studies show that N-Fe/CNT adsorption of Pb???,It is an exothermic and spontaneous process;kinetic studies have shown that a quasi-second-order kinetic model is more suitable for describing the adsorption behavior of Pb???by N-Fe/CNT,mainly chemical adsorption.According to the characterization analysis,the appearance of N-Fe/CNT changed significantly before and after the reaction,and the functional groups such as-OH and C=O reacted mainly.The adsorption,redox,and complexation reactions were the main reactions.The removal test of U?VI?by N-Fe/SFP showed that pH had a great effect on the removal of U?VI?by N-Fe/SFP.The removal effect was best at pH=5 and 180 min,and it was 10 mg/L U?VI?.The removal efficiency was 93.7%,and the adsorption amount was 9.37 mg/g.Isothermal adsorption studies show that the Langmuir isothermal model fits well,indicating that N-Fe/SFP adsorbs U?VI?monolayers.Thermodynamic studies show that the adsorption of U?VI?by N-Fe/SFP is an endothermic,spontaneous process.Kinetic studies show that quasi-second-order kinetic equations can better describe the kinetics of U?VI?adsorption by N-Fe/SFP and show that the adsorption process of U?VI?by N-Fe/SFP is dominated by chemical adsorption.The mechanism analysis shows that the material changes significantly before and after the N-Fe/SFP reaction.The removal of U?VI?is mainly caused by the functional groups such as-OH and C=O,which are mainly adsorption,complexation and redox reactions.