Preparation Of Metal Phosphate Materials And Study On Uranium Adsorption Mechanism

As the most important resource in the development of nuclear industry-uranium,allowing it to migrate and enrich in the environment will cause irreparable losses to organisms and people themselves.Therefore,the development of efficient and economic adsorbent materials is a guarantee project for the development of nuclear energy.In this paper,through a simple preparation method of the synthesis of two kinds of iron phosphate salt Ⅱ/Ⅲ),the morphology structure of the two materials,surface functional groups,element distribution and specific surface area,characterized by batch experiments to test the adsorption performance,finally on the material and explore the possible mechanism of the adsorption of uranium,the final assessment of its practical application value:1.Combining the synthesis of phosphoric acid precursor and co-precipitation method,a facile,technically reproducible and low-cost synthesis method of iron phosphate（FeyPz）was established.The process starts with the synthesis of p-doped carbon dots（pCDs）and then introduces pCDs during the preparation of Fe3O4.Interestingly,the synthesis conditions of FeyPz have a significant effect on its adsorption capacity for uranium（U（Ⅵ））,and the optimized adsorption performance can be obtained by adjusting the functional groups and structure of FeyPz.Compared with FePO4·2H2O and Fe3O4,the absorption performance of FeyPz-10 for U（Ⅵ）is improved by 3561%and 684.5%,respectively.The maximum adsorption capacity of FeyPz-10 based on the Langmuir model was 290.4 mg/g at pH 4.5.In addition,the adsorbent has good reusability and still maintains a high adsorption capacity for U（Ⅵ）after 5 cycles,and the excellent adsorption capacity of the adsorbent FeyPz-10 for U（Ⅵ）is confirmed by XPS analysis mainly It is the result of the reduction of U（Ⅵ）caused by the conversion of Fe2+to Fe3+.2.In this chapter,a novel high surface area iron phosphate（IP）was investigated for the efficient adsorption of uranyl ions in acidic media.The as-prepared IP is amorphous,with a specific surface area（268 m2/g）and total pore volume（1.04 cm3/g）.In particular,compared with amorphous FePO4（67.3 mg/g）and Fe3（PO4）2（H2O）8（33.8 mg/g）,IP（154.6 mg/g）containing iron ions and oxygen-and nitrogen-containing functional groups has good U（Ⅵ）adsorption capacity.The saturated adsorption capacity of IP reached 353.9 mg/g.Meanwhile,IP adsorption was fast,reaching adsorption equilibrium less than 20 minutes,and following pseudo-second-order kinetics and Freundlich model.The D-R adsorption isotherm model and enthalpy values indicated that the process was chemisorption behavior.The ionic strength experiments and adsorption-desorption isotherms showed that the adsorption of U（Ⅵ）was the control step of the inner surface complexation,and the functional groups and structures of the materials did not change significantly after adsorption.In addition to this,XPS analysis revealed that the mechanism of IP capture of U（Ⅵ）was not only related to redox reactions but also to synergistic chemisorption.In this project,two uranium adsorption materials（FeyPz-10 and IP）were successfully prepared.The composition and morphology of the materials were characterized by feasible means of characterization.And through a series of batch experiments to explore its adsorption performance It shows that the material has potential application value in treating uranium U（Ⅵ）in radioactive wastewater,and also provides some ideas for further research of the material.