【摘要】 针对硅微粉中SiO2含量较高且含Fe、Al等杂质的特点,本文研究了一种用无水K2CO3和KOH作熔融剂,钼酸铵作显色剂并用分光光度法测定二氧化硅含量的新方法。实验结果表明,在0.1~0.3 mol/L的酸度下,正硅酸与钼酸铵生成硅钼杂多酸(硅钼黄),选择硅钼黄的吸收波长在410 nm处,表观摩尔吸光系数为8.77×106L.mol-1.cm-1。SiO2浓度在0~1.0 mg/mL范围内符合比尔定律,相关系数r=0.999 6,检出限为0.052μg/mL。本法适用于硅微粉中二氧化硅含量的测定,回收率在99%~101%之间,相对标准偏差(RSD)控制在0.79%~1.8%(n=6)范围内,测定结果与X射线荧光光谱法的结果相一致。该方法亦可推广用于其他高含量二氧化硅样品的测定。更多还原

【Abstract】 Based on the fact that silica fume contained high content of SiO2 and impurities including Fe and Al,a novel spectrophotometric determination method of silicon oxide was studied with anhydrous K2CO3 and KOH as flux and ammonium molybdate as coloring reagent.The results showed that under the acidity of 0.1-0.3 mol/L,normal silicic acid reacted with ammonium molybdate to form silicon-molybdenum heteropoly acid(molybdosilicate yellow).The apparent molar absorptivity was 8.77×106 L·mol-1·cm-1 at the absorption wavelength of 410 nm.Beer’s law was obeyed in the range of 0-1.0 mg/mL for SiO2.The correlation coefficient was r =0.999 6 and the detection limit was 0.052 μg/mL.This method could be applied to the determination of SiO2 in silica fume.The recovery was in the range of 99 %-101 %,and the relative standard deviation(RSD,n=6) was 0.79 %-1.8 %.The determination results were consistent with those obtained by X-ray fluorescence spectrometry.This method could also be used for the determination of other samples containing high-content silicon oxide.更多还原