基于树状分子修饰的新型吸附剂制备及其对复杂基体中铅、镉分离富集性能研究

Macroporous materials are usually applied to sepration and preconcentraiton of lead/cadmium in samples with complex matrix. But the influence of porous structure on the rates of adsorption and eluting is not emphasized in traditional materials preparation. But the target ions easily enter the inner mesoporous of adsorbent and are adsorbed by respective sites, so they can not be easily and even incompletely eluted. This problem influences the accuracy and repeatability of the determination and hinders the application of methods.. In the project, macroporous silica gel will be modified with dendrimer-like molecules to close its mesoporous, and then functional molecules will be bonded to the end of the dendrimer-like molecules to prepare adsorbents for separation/preconcentration of lead/cadmium from sample solution. Based on steric hindrance effect from the dendrimer-like molecule, the target ions would be prevented to enter into the inner mesoporous of silica gel. By the prior adsorption of the end functional groups with lead/cadmium, the adsorption oflead/cadmium with inner groups of dendrimer-like molecules would be prevented, so lead/cadmium will be separated and preconcentrated from the matrix and then be rapidly eluted. The adsorbents performance of seperation/preconcentration for lead/cadmium can be investigated with hydride generation-atomic ?uorescence spectrometry (HG-AFS). After optimization of separation/preconcentration conditions, the adsorbents will be applied to analysis of lead/cadmium in real samples to prove their performances. The target of the object is to prepare efficient materials for separation/preconcentration of ultra-trace lead/cadmium in samples with complex matrix.

测定复杂基体样品中低浓度铅、镉时通常用大孔吸附材料对样品溶液目标物质进行分离富集处理。传统吸附材料没有充分考虑孔隙结构对目标离子吸附与洗脱速率影响，目标离子在分离富集时进入材料介孔内部与相应位点作用造成洗脱缓慢甚至不完全，严重影响测定重复性、结果准确性及方法的应用。本项目以树状分子修饰大孔微球硅胶对其介孔进行封闭，并在树状分子末端键合功能分子制备吸附剂用于铅、镉分离富集。利用树状分子体积位阻效应防止富集过程中铅、镉进入硅胶内部介孔，通过末端功能分子与铅、镉优先作用防止其与树状分子内层基团发生吸附，确保铅、镉快速富集并与基体离子分离的同时，实现其快速洗脱。利用氢化物发生-原子荧光光谱法（HG-AFS）研究吸附剂对铅、镉的富集分离性能。将吸附剂应用于海水等样品中铅、镉分离富集,验证该吸附剂对铅、镉的分离富集性能，为复杂基体中铅、镉分析提供高效可靠的分离材富集材料。

(1)在硅胶表面修饰功硫代苹果酸、硫脲、5-磺基水杨酸和硫代巴比妥酸制备了四种吸附剂，研究其对Pb(Ⅱ)，Cd(Ⅱ)的分离富集性能。建立微柱分离富集-火焰原子吸收光谱测定Pb(Ⅱ)，Cd(Ⅱ)的新方法，方法成功应用于水样中Pb(Ⅱ)，Cd(Ⅱ)的分析。(2)采用发散法制备聚密胺树状分子修饰硅胶，在其末端修饰没食子酸、硫脲和硫代苹果酸得到三个系列新型吸附剂，研究其对于Pb(Ⅱ)，Cd(Ⅱ)的微柱分离富集性能。建立了微柱分离富集-石墨炉原子吸收光谱测定Pb(Ⅱ)，Cd(Ⅱ)的新方法，方法应用于水样中Pb(Ⅱ)、Cd(Ⅱ)分析。(3)发散法制备聚酰胺胺型（PAMAM）(n=1,2,3,4)树状分子硅胶，在PAMAM氨基末端键合没食子酸、硫代苹果酸、水杨醛、L-半胱氨酸和5-磺基水杨酸，制备5个系列吸附材料，研究其对于Pb(Ⅱ)，Cd(Ⅱ)微柱分离富集性能，建立 微柱分离富集-火焰原子吸收光谱测定Pb(Ⅱ)的新方法，和微柱分离富集-石墨炉原子吸收光谱方法测定Pb(Ⅱ)和Cd(Ⅱ)的新方法；方法成功应用于水样、鱿鱼样品、标准样中Pb(Ⅱ)或Cd(Ⅱ)的分析。吸附剂的SEM照片表明，树状分子接枝在硅胶表面形貌改变方面起到主要作用；TG和元素分析结果表明，树状分子接枝量随接枝代数增加而增加；N2吸附热力学曲线表明，树状分子接枝硅胶吸附剂表面具有规整排列的介孔结构，随接枝代数增加，表面孔径逐步变小，部分微孔被树状分子封闭，功能小分子基团主要分布在孔径较大的介孔和大孔，有利于离子与其进行优先吸附。随接枝代数增加，吸附材料的吸附容量增加，在较宽的样品流速范围都能定量吸附待测离子，而且离子的洗脱更加容易。功能小分子基团对待测离子的良好选择性有效消除基体离子在富集和测定过程中的干扰。以静电吸附和络合吸附理论对材料与目标离子吸附机理进行解释。树状分子和选择性小分子基团先后修饰的方法拓展孔隙材料在痕量金属离子分离富集和检测中的应用。