Preparation Of Amidoxime Functionalized Materials And Its Adsorption Of Uranium

The uranium resources on the continent decrease quickly along with the development of nucleus industry. However, the ocean which accounted for 70 % of the total earth contains abundant uranium resources. There is an average of 3.2 milligram uranium in a ton of seawater. It means that the seawater contains more than 4000 million tons of uranium, equally 99.9% of the world uranium reserves. So extracting uranium from sea water will have a bright prospect.This thesis is mainly fouced on the synthesis of amidoxime functionalized materials, and their applications as adsorbents to extract uranium. The concentration of uranium is analyzed through spectrophotometer with azoarsine(â…¢) as chromogenic agent. The amidoxime functionalized materials are obtained by the reaction of hydroxylamine and the material with cyanic(-CN) functional group. The amidoxime functionalized materials are prepared with two methods. (1) Amidoxime functionalized fiber is prepared by reacting polyacrylonitrile fiber with hydroxylamine, resulting from that nitrile group is transformed into amidoxime group. The results show that the concentration of amidoxime group on the obtained amidoxime functionalized fiber is 11.45 mmol/g at 70 oC with DMSO as additive. The adsorption rate of uranium is faster with higher initial concentration of uranium at higher temperature. The maximum adsorption capacity of uranium is 24.82 mg/g at pH=5.0. The separation coefficients of uranium-magnesium and uranium-calcium are 20.26 and 4.01 respectively. It indicates that the amidoxime functionalized fiber has large adsorption capacity and high selectivity for uranium. To enhance the mechanical properties of amidoxime functionalized fiber, the PAN fibers is pretreatmented by crosslinkage with Diethylenetriamine before reacting with hydroxylamine. The results show that the mechanical property of crosslinking material is significantly improved from the aparent and the adsorption capacity of uranium is insignificant difference with the material un-crosslinked. (2) Polyacrylonitrile powder reacts with aqueous hydrochloric acid hydroxylamine to prepare amidoxime functionalized hybrid material. The results show that the adsorption rate of uranium is faster with higher initial concentration of uranium at higher temperature. To enhance the mechanical properties of the material, amidoxime functionalized material is blended with TiO2 sol. The mechanical property of hybrid material is significantly improved from the aparent and their adsorption properties of uranium are insignificant difference with the material un-blended.In addition, the adsorption of Cu2+,Ni2+,Pb2+,Hg2+ by the amidoxime functionalized materials is discussed. It shows that the materials also get preferable adsorption capacity to these heavy metal ions. The amidoxime functionalized materials can be applied to remove heavy metal ions and get some precious metals recovery. Furthermore, the uranium adsorption mechanism is preliminarily studied, based on exploration to this kind of amidoxime functionalized materials and predecessors' research.