沸石负载对叔丁基杯[4]芳烃乙酸对铀的吸附行为

以对叔丁基杯4]芳烃与溴乙酸乙酯为主要反应底物合成了对叔丁基杯4]芳烃乙酸,然后将其负载在沸石上,红外光谱显示合成物具有杯4]芳烃乙酸的特征结构,扫描电镜分析表明对叔丁基杯4]芳烃乙酸成功负载于沸石之上,且分布均匀,分散性良好.通过静态吸附实验,结果表明在pH值 4,对叔丁基杯4]芳烃乙酸/沸石的负载比0.025/1,吸附剂用量0.5g,铀初始质量浓度10mg/L,吸附时间30min时,沸石在负载了对叔丁基杯4]芳烃乙酸后,对溶液中铀的吸附率从30%左右提高到93%.沸石和负载沸石吸附动力学行为均符合准二级动力学模型,但负载沸石对铀的吸附速率明显高于沸石.沸石和负载沸石吸附等温式都符合Langmuir吸附等温线,说明都为单分子层吸附;由此推导出的最大吸附量Qm从16.8919提高到32.5733mg/g,这主要是因为沸石负载了对叔丁基杯4]芳烃乙酸增加了吸附点位.吸附铀前后的红外光谱表明,负载沸石对铀的去除主要依靠对叔丁基杯4]芳烃乙酸与铀的强络合作用和Si—O和Al—O的吸附作用,两种作用的协同加快了吸附速率,增加了吸附容量.

Adsorption behavior of uranium by zeolite loaded with p-calix[4]arene acetate

P-calix4]arene acetate was synthetized by the main reaction substrates, p-tert-butyl-calix4]arene and ethylbromoacetate, subsequently loaded onto zeolite. Infrared spectra demonstrated that the synthetized compound had the structure characteristics of p-calix4]arene acetate; Scanning electron microscope analysis indicated that p-calix4]arene acetate was loaded on zeolite successfully, evenly and dispersedly. By the static experiments, the results showed that when the pH = 4, absorbent dosage was 0.5g, initial uranium concentration was 10mg/L, p-calix4]arene acetate/zeolite = 0.025/1, and the reaction time was 30min, the adsorption efficiency of zeolite increased from about 30 % to 93 % after loadeding p-calix4]arene acetate. Besides, the adsorption reactions of uranium by zeolite and zeolite loaded with p-calix 4]arene acetate (Referred to as the loaded zeolite) could be both described by pseudo-second-order kinetic model, while the absorption rate of loaded zeolite was faster than that of zeolite. Moreover, both of the 2 absorption reactions followed the Langmuir adsorption isotherm, whereas the maximum adsorption amount inferred by Langmuir model ascended from 16.8919 to 32.5733mg/g, which was due to fact that zeolite had increased the absorption sites on its surface after loading p-calix4]arene acetate. In addition, infrared spectra analyses before and after adsorbing uranium demonstrated that the loaded zeolite mainly depended on the strong complexion of p-calix4]arene acetate and the sorption of Si-O and Al-O to remove uranium, and these 2kinds of functions affected synergistically to speed up the rate of adsorption and increase adsorption amount.