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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。
In this paper, natural sand was modified with different concentrations of sodium hydroxide solution and the surface structure, specific surface area and functional groups of modified natural sand were investigated by scanning electron microscopy, static nitrogen adsorption and infrared spectroscopy, and the modification conditions were optimized. The sand was used as filler to separate and enrich microcolumn. FAAS was used to study the dynamic adsorption of Pb2 + by modified sand and its application in the trace Pb2 + enrichment and determination. The results showed that the surface of natural sand Surface area, surface pore volume and particle size distribution changed, the surface became rougher, the pore volume and specific surface area increased, the silanol infrared absorption peak intensity was also significantly enhanced; its specific surface area of 12.55m2 / g, the average The pore diameter was 25.29 nm and the average pore volume was 48.04 mm3 / g (D <8.3 nm). At room temperature, the solution pH was 5.5 and the loading flow rate was 1.50 m L · min-1. The dynamic adsorption capacity of Pb2 + was 32.6 mg · g-1, and the adsorption rate was 93.6%. When the concentration of Pb2 + was 0.5mol·L-1, the elution rate was 97% at the flow rate of 3.0m L · min-1. It is suitable for the separation, enrichment and determination of trace Pb2 + with satisfactory results.