Study On The Adsorption Of Uranium On Amidoxime Modified Graphite Felt Electrodes

With the development of the nuclear power industry,the demand and use of uranium are more and more worldwide,and the production of uranium containing wastewater has a negative impact on the environment and the human body.More and more attention has been paid to its treatment.Electrochemistry has a good application prospect in wastewater treatment,because its operation is simple and the cost is controllable.At the same time,the effect of decontamination has a unique advantage compared with other treatment methods.The main contents of this study include two parts: The first is the preparation of the amidoxime modified graphite felt electrode.Than study the law of amidoxime reaction on the graphite felt and analysis of the modified electrode.Graphite felt was used as electrode substrate,and N-N dimethylformamide(DMF)was used as solvent to dissolve the polyacrylonitrile powder(PAN)and coated it on the electrode surface.Amidoxime reaction was finished in aqueous solution with hydroxylamine hydrochloride and sodium hydroxide,then we got amidoxime modified electrode.And study on the effects of time,temperature and additives on the amidoximation.The results show that the reaction was completed rapidly between 2 and 4 hours,and the nitrile conversion rate(CR)reached 60% at 4 hours.At the same time,The reaction speed is slow when the temperature is low.When the temperature rises to 65,the reaction speed increases rapidly.When the temperature reaches 70,the reaction is basically completed,and the temperature will continue to improve the conversion rate basically unchanged.Different additives also have a significant effect on the reaction.By comparison of ethanol,methanol,N,N-two methyl formamide(DMF)and two methyl sulfoxide(DMSO),the main function of the additive is to enhance the affinity of the reactant to the solution,and to accelerate the diffusion of hydroxylamine molecules.The analysis of products by Fourier transform infrared spectroscopy(FTIR)showed that the reaction did occur.Secondly,The paper also studies how the electric field on the amidoxime modified electrode applied in different conditions(AO-ELECTRODE)affect the adsorption properties.The results show that The applied electric field has a significant effect on the adsorption properties of the modified electrode.In the case of high uranium concentration(1000ppm),the adsorption capacity of the modified electrode was 4 times that of pure adsorption,reaching 650mg/g.pH also has a significant effect on uranium adsorption process.The optimum pH value of pure adsorption is 5,while the optimum adsorption pH value with external electric field is 6.The influence of external electric field on the adsorption performance of modified electrode is small,and the adsorption curve is basically coincided under constant potential and pulse potential.The applied potential has a more obvious influence on the adsorption performance.With the potential of potential increasing,the adsorption rate has a more obvious increase,but the hydrogen precipitation begins when the voltage exceeds 4V.After comprehensive analysis,it is concluded that the optimum conditions for the preparation of modified electrodes are 4 hours,and the temperature of 70 degrees is two methyl sulfoxide.The conversion rate of nitrile(CR)was 65%.When the applied potential is 3V,the maximum adsorption capacity is 658mg/g at 24 hours,which is 4 times higher than that of pure adsorption.This indicates that the adsorption properties of the amine groups can be greatly improved under the influence of external electric field.