二苯碳酰二肼分光光度法测定氮化硅铁中铬

氮化硅铁是一种重要的耐火材料,实验研究了应用二苯碳酰二肼分光光度法测定氮化硅铁中铬元素含量的分析方法。针对试样分解方法、氧化条件、显色条件、干扰消除等进行了试验研究,确定了最佳分析条件。试样于镍坩埚中以2 g氢氧化钠作为熔剂在650 ℃熔融10 min分解,在热水中浸取熔块后,以氢氟酸、高氯酸冒烟除去试样中的硅元素。用硫酸(1+9)溶解盐类后,在硫酸介质中以2.0 mL 10 g/L高锰酸钾溶液氧化铬至正六价,再加入过量的200 g/L碳酸钠溶液沉淀分离铁、镍等共存元素,最后在0.05～0.2 mol/L硫酸中利用铬与二苯碳酰二肼反应显色对其进行了测定。应用实验方法对氮化硅铁样品进行测定,测定值与电感耦合等离子体原子发射光谱法(ICP-AES)测定值一致,测定结果的相对标准偏差(RSD,n=11)小于2%;加标回收试验结果表明回收率为101%。

Determination of chromium in ferrosilicon nitride by diphenylcarbonhydrazide spectrophotometry

Ferrosilicon nitride is a kind of important refractory materials. An analysis method of chromium content in ferrosilicon nitride was investigated by diphenylcarbazide spectrophotometry. The optimal analysis conditions were obtained by optimal experiments including sample decomposition method, oxidation condition, coloring condition and elimination of interference. The sample was melted in nickel crucible at 650 ℃ for 10 min with 2 g of sodium hydroxide as flux. The melt was leached with hot water. Then, silicon in the sample was removed by hydrofluoric acid and perchloric acid smoking. The salts were dissolved with sulfuric acid (1+9), and chromium in the sample solution was oxidized to chromium (VI) with 2.0 mL of 10 g/L potassium permanganate solution in sulfuric acid medium. After that, excessive 200 g/L sodium carbonate solution was added to precipitate and separate the coexisting elements such as iron and nickel. Finally, the coloring reaction of chromium with diphenylcarbazide was conducted in 0.05-0.2 mol/L sulfuric acid for the determination. The proposed method was applied to the determination of ferrosilicon nitride sample. The results were consistent with those obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES). The relative standard deviation (RSD, n=11) was less than 2%. The recovery test of standard addition indicated that the recovery was 101%.