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本文研究了用二苯基碳酰二肼光度法测定ZnO压敏陶瓷中Cr_2O_3的含量。试样经粉碎研磨之后用焦硫酸钾熔融分解,三价铬在有硝酸银存在下,用过硫酸铵氧化成六价铬,煮沸破坏过剩的过硫酸铵,用亚硝酸钠还原七价锰为二价锰,加入尿素破坏亚硝酸。在微酸性溶液中,六价铬与二苯基碳酰二肼反应生成可溶性的紫红色络合物。络合物的吸收峰在540nm波长处,反应的灵敏度为0.0015μg·ml~(-1)·cm~(-1),克分子吸光率=3.4×10~4。测定Cr_2O_3的干扰元素仅产生于比铬的含量高得多的Fe·V·Mo和Hg,但其灵敏度远较铬(Ⅳ)低。该方法灵敏高,选择性好,分析周期短,能准确测定ZnO非线性电阻片中Cr_2O_3的含量,也
In this paper, diphenyl carbazide spectrophotometric determination of Cr 2 O 3 in ZnO varistor ceramics was studied. After grinding and grinding the sample with potassium pyrosulfate melt decomposition of trivalent chromium in the presence of silver nitrate, ammonium persulfate oxidation into hexavalent chromium, boil the destruction of excess ammonium persulfate, with sodium nitrite reduction of seven manganese Manganese dioxide, adding urea to destroy nitrous acid. In a slightly acidic solution, hexavalent chromium reacts with diphenylcarbazine to form a soluble fuchsine complex. The absorption peak of the complex was at 540 nm. The sensitivity of the reaction was 0.0015 μg · ml -1 · cm -1, and the molar absorptivity was 3.4 × 10 ~ 4. The interfering elements for the determination of Cr 2 O 3 are produced only from Fe · V · Mo and Hg, which are much higher in content than chromium, but their sensitivity is much lower than that of chromium (Ⅳ). The method has high sensitivity, good selectivity and short analysis period, and can accurately measure the content of Cr 2 O 3 in the ZnO varistor sheet.