Desorption Behavior Of Uranium Loaded Fiber Type Amidoxime Based Functional Polymer Material

As one of the clean energy sources,nuclear power has an extremely important economic and strategic position.Uranium is an important resource for the development of nuclear power.China is a country that is not rich in uranium resources,accounting for only 3%of the global uranium resources.The content of uranium in seawater is only 3.3 ppb.But the total quantity of uranium is more than 4.5 billion tons,which is more than 1,000 times that of terrestrial uranium resources.The research on uranium recovery from seawater is one of the most challenging tasks that have not been resolved since the 1950s.Some chelating adsorbents containing amidoxime groups show much better adsorption ability and selectivity.for uranium over others,but the efficient desorption of the loaded uranium materials has not been achieved.Finding new technical pathways are therefore significant.For this purpose,the desorption behavior of uranium from the loaded amidoxime based adsorbents was studied by different alkaline solutions in this work.The revealed desorption mechanism of uranium was discussed.The main results were as follows.1.The loaded uranium functional polymer materials were prepared and characterized.The desorption of uranium with sodium hydroxide,potassium hydroxide and hydroxylamine solutions were studied respectively.The influence of some factors such as temperature,contact time and others on uranium desorption were investigated.The absorption mechanism was discussed.The desorption efficiency of uranium with sodium hydroxide or potassium hydroxide solution was lower than 10%,while it reached nearly 100%by desorption with 5 M hydroxylamine solution.2.Based on the coordination between carbonate and uranyl ions,the desorption of uranium with potassium carbonate,potassium bicarbonate and sodium carbonate were studied respectively.The results showed that the carbonate solution has obvious desorption ability,but the desorption efficiency of uranium was less than 75%.3.The desorption of uranium with a binary solution of carbonate and hydrogen peroxide was studied.The influence of some factors such as H2O2 concentration,temperature,contact time,and desorbent formulation on the uranium desorption was examined.The desorption efficiency of uranium by desorption with 1 M Na2CO3+0.2-0.8 M H2O2 was in the range of 98.3 to 100%.The optimal desorption conditions were obtained,and a desorption process was proposed.4.The desorption-adsorption cycle of the loaded uranium functional materials was performed for 10 times.The changes in appearance,morphology and microstructure of the materials before and after cycle were characterized by SEM,UV-vis,XPS,FT-IR,EDS and others.The adsorption and desorption mechanism were clarified.The dynamic equilibrium of formation and transformation of the complex specieses between a binary Uμ2(Cμ3)34-and a ternary Uμ2(μ2)(Cμ3)24-were studied.This provides valuable theoretical and experimental basis for efective desorption and recovery of uranium from seawater.