修饰沙粒对Pb(Ⅱ)的吸附性及其在痕量Pb(Ⅱ)分离富集与测定中的应用

Adsorption of lead ions onto modified natural sands and application on the trace lead separation and determination

本文用不同浓度的氢氧化钠溶液修饰天然沙粒并通过扫描电镜、静态氮吸附和红外光谱法考察了修饰天然沙粒的表面结构、比表面积和功能基团,优化了修饰条件;以修饰天然沙粒为填料制备分离富集微柱,采用FAAS着重研究了修饰沙粒对Pb2+的动态吸附及其在痕量Pb2+分离富集和测定中的应用;结果表明:天然沙粒被修饰后其表面形貌、比表面积、表面孔体积和粒径分布发生变化,表面变得更粗糙,孔体积和比表面积增大,硅羟基红外吸收峰强度也明显增强;其比表面积为12.55m2/g,平均孔(坑)径为25.29nm,平均孔体积48.04mm3/g(D<8.3 nm);在室温下,溶液pH为5.5,上样流速为1.50m L·min-1时,修饰天然沙粒对Pb2+的动态吸附量可达到32.6 mg·g-1,吸附率为93.6%,选用0.5mol·L-1的盐酸溶液以3.0m L·min-1流速进行洗脱,洗脱率为97%;适用于痕量Pb2+的分离富集和测定,结果令人满意。

The present research was aimed at the modify of natural sands with NaOH in different concentration,the condition of modifying was optimized. the size distribution,the surface morphology,the surface area,the hole volume and the functional radical of MNSs were analyzed using FTIR,SEM,NSA; after modifying,the surface morphology was changed,the surface area and hole volume were increased; adsorption properties of Pb（Ⅱ） onto modified natural sands（ MNSs） and separation of trace Pb（Ⅱ） from aqueous solution were mainly studied using FAAS as determination measures. the adsorption of Pb（Ⅱ） onto MNSs were optimized. The experimental results showed that at the optimal adsorption conditions such as,the procedure was carried at room temperature,pH of solution was 5. 5,the flow rate（ m L·min^-1） of sample and eluent were1. 5 and 3. 0 respectively,the adsorption capacity of Pb（Ⅱ） onto MNSs can reach 32. 6 mg·g^-1. Adsorption rate was 93. 6%. surface area,pore size and hole volume were 12. 55m2·g^-1,25. 29 nm and 48. 04mm^3·g^-1（ D8. 3 nm） separately. Pb2＋ions preconcentrated on MNSs was eluted with 0. 5mol·L^-1chloride acid. the desorption rate reached 97%.