Study On Fabrication And Uranium Recovery From Seawater Of Amidoxime-Functionalized Porous Micro-Spheres

The ocean is extremely rich in uranium resource,which is approximately 1,000 times than onshore deposits.With the rapid development of China’s nuclear power,the demand for uranium ore,as the main nauclear fuel,is gradually increasing and there is a serious shortage of onshore uranium deposits.The research on seawater uranium extraction is of a great strategic significance to guarantee China’s energy security.Aminoxime-functionalized materials are one of most important uranium adsorbents at present.However,due to the complex environment in ocean,a large amount of various coexisting competitive ions and ulta-low uranium concentration,it is still necessary to further improve the uranium adsorption performance of them and reduce the cost,for the industrialization of seawater uranium extraction.In view of this vital problem to be solved,based on supramolecular interaction and solid phase template method,a new kind of poly（amidoxime）-loaded porous microspheres with ultra-high specific surface area has been fabricated in this study,which can greatly improve the uranium adsorption efficiency/speed of amidoxime-functional groups with a very low cost.This study will provide a simple but high-efficient new method for realizing large-scale uranium extraction from seawater.This work can also inspire the further design and exploration of new ultra-efficient amidoxime-based uranium adsorbents and even other types of uranium adsorbing materials,which has great practical application value and important theoretical significance.The main research contents:（1）Supramolecularly Poly（amidoxime）-Loaded Macroporous Resin for Fast Uranium Recovery from Seawater.Based on the supramolecular interaction force,after the macroporous resin（HP-20）immersed in polyamidoxime（PAO）solution,the PAO can be firmly loaded on the nanopore surface of HP-20,thus the supramolecularly poly（amidoxime）-loaded macroporous resin（PLMR）was obtained in a one-step method.Because the pore surface with high specific surface area can load a PAO mono layer with molecular thickness,different from the existing adsorbents containing a large amount of low-efficient amidoxime functional groups,PAO on PLMR has a high-efficient uranium adsorption performance.As a result,the uranium adsorption capacity of the PLMR can reach 157±7 mg/g（that of the PAO in PLMR can reach1039±46 mg/g）,in 32 ppm uranium-spiked seawater for 120 h;in natural seawater for only10 days,the uranium-uptake amount of the PLMR can reach 2.14±0.21 mg/g,and its average uranium adsorption speed can reach 0.214 mg/（g·day）,which is outstanding among reported amidoxime-based adsorbents.This new PLMR adsorbent,with excellent uranium adsorption capacity,simple fabrication process and low cost,will be an excellent candidate for large-scale uranium extraction form seawater.（2）Based on Solid-Phase Template Method Preparation of Fully Poly（midoxime）Porous Microspheres Uranium Recovery Performance from SeawaterOn the basis of the research in the previous chapter,in view of the low content of PAO in PLMR（about 1/7 of the PLMR mass）,a fully poly（midoxime）porous microspheres（FPPM）with fully poly（amidoxime）has been designed based on the solid phase template method,to further improve the uranium adsorption performance.Using Na₂CO₃ particles as a solid phase template,FPPM can be achieved by a two-step method through dropping PAO dimethylformamide solution into anhydrous ethanol and then transferring it into ultrapure water.This FPPM porous microspheres can maintain a high specific surface area while further significantly increasing the PAO content（about 100%）,thus obtaining a high-enhanced uranium adsorbing capacity.After 120 h in 32 ppm U-spiked seawater,the uranium adsorbing capacity of the FPPM can reach 722±23 mg/g;after 10 days in natural seawater,the adsorption capacity of FPPM uranium is 94.9%higher than that of PLMR,which can reach 4.17±0.29 mg/g.This new FPPM adsorbent has the advantages of simple preparation method and high uranium adsorption performance,which has great potential application value in the industrialization of seawater uranium extraction.