| Uranium is an important strategic resource of a country which is an important nuclear fuel resource and one of the major hazardous elements in radioactive liquid wastes.Compared with the ocean,the uranium resources on land are limited and the extraction is difficult.With the development of society,the growing demand for uranium resources results in the lack of land uranium resources increasingly.At the same time,large amounts of waste liquid containing uranium are also potential environmental pollutants.So,highly efficient recovery of uranium from aqueous solutions is of extreme importance from the points of view of energy security and environmental protection.Compared with other separation methods,adsorption method is one of the most widely used uranium recovery methods because of its low cost,easy operation and wide adaptability.The key of technique of adsorption method is to development suitable adsorbent.The amidoxime group has been grafted onto the surfaces of various substrates because of its strong selective adsorption capacity toward uranium.Calixarene and polystyrene resin are widely used in the study of the preparation and adsorption properties of adsorbents due to their special structures and superior properties.In this work,the amidoxime group has been grafted to synthesis the following two kinds of adsorption materials based on the characteristics of calixarene and polystyrene resin and the adsorption properties for uranium has been studied:1?Amidoxime modified thiacalix [4] areneThe nitrile group was grafted with thiacalix [4] arene by substitution reaction and amidoxime thiacalix [4] arene(TC4A-AO)adsorption material was successfully prepared through amidoximation.The influence of pH value,contact time,concentration of uranium ion and temperature on the adsorption performance was investigated through static adsorption test.The results show that the amidoxime thiacalix [4] arene has certain adsorption capacity and higher temperature is favorable to the adsorption for uranium.2?Amidoxime modified polystyrene resinDiaminomaleonitrile has been grafted with chloromethylated polystyrene matrix through the polymer reaction and then amidoxime polystyrene chelating resin(PSAO)was prepared successfully by reacting with hydroxylamine hydrochloride.The influence of pH value,contact time,concentration of uranium and temperature on the adsorption performance of amidoxime resin material for uranium was investigated through static adsorption test.The results show that the chelating resin for uranium ions showed a strong adsorption capacity.When the pH of the adsorption solution is 6,the adsorption capacity can reach as high as 58mg/g.The adsorption data of mixture ions showed that the amidoxime chelating resin has strong selective adsorption for uranium.Desorption experiments showed that the elution rate can reach as high as 99.8% when the resin after adsorption was eluted by 6mol/L nitric acid solution. |
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