抗坏血酸作还原滴定剂 连续测定铁矿中的全铁和亚铁

RESEARCH ON THE APPLICATION OF ASCORBIC ACID USED AS REDUCTI METRIC TITRANT FOR THE DETERMINATION OF TOTAL IRON AND FERROUS IRON IN IRON ORES SUCCESSIVELY

本文采用硫酸—盐酸—氢氟酸溶矿,用稳定的抗坏血酸作还原滴定剂,以磺基水杨酸为指示剂,滴定铁矿中的高铁后,溶液用过硫酸铵完全破坏抗坏血酸亚铁络合物,并氧化所有亚铁成为高铁,然后再用抗坏血酸滴定其中的全铁,以此达到全铁和亚铁的连测。本法操作简单,并消除了汞、铬对水体的污染。文中应用本法对六种含铁量不同的铁矿管理样进行了测定,其结果和原结果基本符合,相对误差一般不超过千分之五。

In this paper, after the digestion of iron ore with a mixed acid H_2SO_4—HCl—HF, ascorbic acid as a reductimetric titrant is used for the determination of ferric iron firstly with sulfosalicylic acid as indicator. And then the titrate, which contains ferrous iron and ferrous complex compound with dehydroascorbic acid, oxidized to ferric iron completely with (NH_4)_2S_2O_8, is titrated again with the same ascorbic acid. In such a way, the total iron and ferrous iron could be determined in one and the same sample successively. The operational procedure of "Ascorbinometry" used to determine iron is a simple method and it is also a better one than that of dichromate method to keep water from contamintion with HgCl_2 and dichromate. By this methop six control specimens with different iron contents are determined and compared, and almost the same results are obtained as the indicated values. The relative errors of total iron and ferrous iron are found to be below 0.5％ respectively.