Preparation Of Graphene–thiacalixarene Composites And Study On Their Adsorption Property

Nowadays,it is essential to make full use of nuclear energy resources and achieve nuclear waste minimization and safe disposal for the sustainable development of China’s nuclear energy.Spent fuel reprocessing is the most difficult step in the circulation process of nuclear fuel,so the research on spent fuel reprocessing process for separation and enrichment of nuclides is a very urgent task.Futhermore,Adsorption,possessing operability and low cost,is one of the best methods to separate these radioactive wastes.As a result,the separation materials with high selectivity have been hotspot to research in the world.Graphene,owninging many advantages such as large specific surface,high absorption quality,recently have attracted much scientific interest in the field of absorbing material.In addition,thiacalixarene exhibits the superiority of recognition toward metal ions owing to its high structure stability and easy modification.In this work,efficient adsorption of the radionuclides from aqueous phase were performed based on graphene composite.A thiacalixarene-functionalized graphene oxide（GO）composite were synthesized by composing graphene oxide and thiacalix[4]arene（TC4A）result from the process of esterification and polymerization.And these prepared materials then were characterized by SEM,TGA,FTIR,NMR and the Raman spectroscopy analysis.Then the composite was used to adsorb for its super absorption ability by researching the effect of adsorption conditions,such as the value of PH,contact time and the initial concentration of the metal ions.Furthermore,adsorption mechanism was investigated by adsorption kinetic,adsorption isotherm and adsorption thermodynamics.The results from determination and characterization indicate that the suface of GO–TC4A presenting flower shape and porous structure and the characteristic peak of functional groups about GO-TC4A have changed a lot compared with GO,which ilustarte that TC4A was attached to the surface of GO and GO-TC4A was prepared as well as TC4A successfully.From adsorbing experiments,it is seen that The maximum adsorption of GO-TC4A removing a high concentration of radionuclides（Nd（III）,Sr（II）,and Rb（I））from water is 337.83,101.11,and 164.47mg·g^-1,respectively,during the removal process,which exhabits advantage over GO.the best ranges of PH values of controlling the adsorption process of GO andGO-TC4A towards Nd（III）,Sr（II）and Rb（I）are 6⁷,7⁹ and 4⁶,respectively,and all the saturated adsorbption capacity of GO-TC4A is larger than which of GO.In adddition,the adsorption equilibrium time of GO-TC4A toward Nd（III）,Sr（II）and Rb（I）is 110min,80min,and 110min repectively.The adsorption data of experiments is much better fit the pseudo-second-order model that two other models,which show that the rate control have main effect on the adsorption process.The adsorption isotherm of GO-TC4A towards Nd（III）is the most suitable to the Freundlich model,yet the adsorption isotherm of GO-TC4A towards Sr（II）and Rb（I）conforms to Langmuir model.Furthermore,thermodynamic studies indicated that the adsorption behavior of the GO-TC4A towards Nd（III）,Sr（II）,and Rb（I）ions was an endothermic and spontaneous natural process.In general,GO-TC4A,not only inheriting merits of GO but also promoting peculiar molecular recognition ability of TC4A,could potentially be applied to remove radionuclides from aqueous solution.