A process of microwave pyrolysis treatment of amidoxime functionalized fiber and enrichment of uranium for uranium extraction from seawater

A process for efficient enrichment of uranium from seawater on fiber was designed. • Seawater uranium extraction fiber after real sea trial was used in the study. • Seawater uranium extraction fiber after repeated use was treated by microwave pyrolysis. • The uranium in the solution was concentrated and purified by ion exchange method. • Lay the foundation for the closed loop of seawater uranium extraction project Developing an efficient process suitable for the treatment of amidoxime-functionalized fibers after multi-cycles using and the enrichment of uranium is crucial for the closed-loop of uranium extraction from seawater. The enrichment process is divided into four major steps, which are microwave pyrolysis, acid leaching of uranium-containing ash, ion exchange and chemical precipitation. A total of 9.14 g of uranium-containing ash was obtained by microwave pyrolysis of 100 g of fiber at 800 °C. Uranium in uranium-containing ash exists in the form of uranium oxide dominated by UO 3 . Then, the uranium-containing ash after pyrolysis was leached with 1 M sulfuric acid solution, and 97.12% uranium could be leached. Through high resolution mass spectrometry and simulation calculation, it was found that uranium in the leaching solution mainly existed in the form of [UO 2 (SO 4 ) 3 ] 4− anionic complex. D201 resin was used to exchange the uranium in the acid leaching solution. The enrichment efficiency of uranium was 98.22%, and the distribution ratio of uranium was about 55.07. Finally, ammonia was used to precipitate uranium, and the precipitation efficiency was 99.43%, and 346.51 mg of uranium compound was obtained. The uranium enrichment efficiency of the whole process is about 94.86%. The mass fraction of uranium in the uranium compound was about 28.3%. It exists in the form of hexavalent uranium oxide. This study contributes to the realization of closed-loop and industrialization in the field of seawater uranium extraction. Download: Download high-res image (266KB) Download: Download full-size image