Synthesis Of A Novel Silica-based Macroporous HNA/SiO₂-P Adsorbent And Its Adsorption Behavior For Uranium From Aqueous Solutions

As an important raw material of nuclear energy,uranium is a radionuclide.It is very easy for uranium to move with environment,and it is detrimental to human health.Thus,it is essential for us to remove uranium from water solution.In order to separate and pre-concentrate uranium from aqueous phase,a novel silica-based adsorbent was prepared by impregnating nalidixic acid（HNA）into a macroreticular silica/polymer composite support（SiO₂-P）with a mean diameter of 60μm.The character of adsorbent was evaluated by SEM,FT-IR,XRD and TG-DTA.Adsorbent is porous microspheres particles,and the most pore diameter of particles are about 40 nm.HNA was impregnated into silica-P successfully,and the synthesis had no effect on the structure and function group of HNA.The synthesized adsorbent showed an admirable stability at lower pH values in aqueous solution.However,the maximum leakage percentage in aqueous phase was about 83%at pH 13.The adsorption behavior of uranium from aqueous solution onto the adsorbent was studied in batch experiments.Experimental results indicated that HNA/SiO₂-Pshowed strong adsorption for uranium in a wide range of pH from 3.5 to 10.0,and the maximum adsorption capacity was35.5 mg/g.In addition,HNA/SiO₂-P exhibited good selectivity for U（VI）and showed weak or bare adsorption affinity to foreign ions,such as Na⁺,Mg²⁺,Mn²⁺,Cr³⁺,Cl^-,and so on.Kinetic and isotherm of uranium adsorption were in accordance with the pseudo-second order kinetic model and Langmuir isotherm adsorption model,respectively.Moreover,U（VI）sorption was found to be an endothermic reaction and spontaneous process under experimental state.The desorption behavior of uranium from adsorbent was investigated in batch experiments.It was found that the solution with 0.5M HNO₃ is better for desorption,and achieved the best effect of desorption at the time of 60 seconds.What’s more,the column experiments shows that the adsorption capacities of three regenerations were about 17.12 mg/g,17.09 mg/g and 16.71 mg/g.It indicated that the adsorbent maintained the adsorption property.In this thesis,the adsorption properties of uranium from aqueous solution onto HNA/SiO₂-P adsorbent were studied in detail.Consequently,it is significant for the research of water radioactive pollution and its treatment.