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本文提出用分光光度硅钼蓝法测定石墨中微量硅。着重研究了酸度和钼酸铵浓度对钼酸形成的影响,指出在钼酸铵浓度增高时钼酸形成的合适的pH范围也随之变大;溶液pH不同时,钼酸铵的影响程度也不同。我们认为,钼酸铵浓度为2.2×10~(-2)M,pH范围为0.9—1.1时对硅钼酸的形成较适宜。此外,还研究了钠盐对硅钼酸形成的影响和铁、钛对钼蓝法测定硅的影响。拟定了用无水碳酸钠分解石墨灰分,酸中和,钼蓝法测定石墨中微量硅的分光光度法。这个方法比较简便,重现性好,最大相对标准偏差为±9%(含硅量为4×10~(-4)%,测定四次),加入试验的回收率为96—110%,方法的测定下限为5×10~(-5)5%。
This paper presents the determination of trace silicon in graphite by spectrophotometric method. The effects of acidity and concentration of ammonium molybdate on the formation of molybdic acid were emphatically studied. It was pointed out that the suitable pH range of molybdic acid formation increased with the increase of ammonium molybdate concentration. When the solution pH was different, the influence of ammonium molybdate different. In our opinion, the concentration of ammonium molybdate is 2.2 × 10 -2 M, and the formation of silicomolybdic acid is more suitable when the pH is in the range of 0.9-1.1. In addition, the effect of sodium salt on the formation of silicomolybdic acid and the effect of iron and titanium on the determination of silicon by molybdenum blue method were also studied. A spectrophotometric method was developed for the determination of trace silicon in graphite by using anhydrous sodium carbonate to decompose graphite ash, acid neutralization and molybdenum blue method. This method is relatively simple, reproducible, the maximum relative standard deviation of ± 9% (silicon content of 4 × 10 ~ (-4)%, measured four times), adding the test recovery was 96-110%, the method The lower limit of determination is 5 × 10 ~ (-5) 5%.