碱熔-钼蓝光度法测定萤石中二氧化硅含量

Determination of silica content in fluorite by alkali melt-molybdenum blue photometry

目的通过碱熔-钼蓝光度法对萤石中二氧化硅含量展开测定。方法样品经氢氧化钾熔融,以水浸取,用硫酸酸化,然后在弱酸性溶液中,硅酸与钼酸铵生成可溶性的黄色硅钼杂多酸,提高酸度,用还原剂将硅钼黄还原成硅钼蓝,在波长700 nm处测量吸光度,测得二氧化硅含量。大量氟干扰,加入铝盐消除。结果采用碱熔-钼蓝光度法进行萤石中二氧化硅含量测定,二氧化硅具备良好的校准曲线线性,线性回归方程为Y=0.34733ρ+0.00228,相关系数R=0.9999;方法精密度在1.5%以内,用国家标准物质进行准确度测量,相对标准偏差<2%。结论经研究发现,采用本方法对萤石样品中二氧化硅含量测定,精密度和准确度良好,满足相关标准要求。

Objective Determination of silicon dioxide in fluorite by alkali fusion-molybdenum blue spectrophotometry.Methods The method is melted with potassium hydroxide,extracted with water and acidified with sulfuric acid,then,in a weak acidic solution,silicic acid and ammonium molybdate form soluble yellow silicomolybdic heteropoly acids,to improve acidity,reduce silicomolybdate yellow to silicomolybdate blue by reducing agent,the absorbance was measured at 700 nm and the silicon dioxide content was measured.A large number of fluoride interference,the addition of aluminum salt to eliminate.Results Determination of silicon dioxide in fluorite by alkali fusion-molybdenum blue spectrophotometry,the silicon dioxide has good calibration curve linearity,the linear regression equation is Y=0.34733ρ+0.00228,the correlation coefficient was 0.999;the precision of the method is less than 1.5%,the accuracy was measured with the national reference materials,and the relative standard deviation(RSD)was less than 2%.Conclusion It was found that the precision and accuracy of this method for the determination of silicon dioxide in fluorite samples were satisfactory and met the requirements of relevant standards.