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重铬酸钾容量法测定铁,由于加入大量汞盐,污染环境。因而近年来有许多工作者致力于无汞测定铁的实验研究。铁的络合滴定一般采用磺基水杨酸为指示剂,但终点变色不够敏锐。本文以埃依铬氰R(ECR)-溴代十六烷基三甲铵(CTMAB)-铁(Ⅲ)三元络合物为指示剂,用EDTA络合滴定铁,经实验表明滴定终点敏锐。考察了共存离子的干扰,实验表明22毫克锰,13毫克铝,10毫克钙、铅、锌、砷、铋,6毫克镁,5毫克钛、汞、银,2毫克铜,1.6毫克锑不干扰测定。由于锰的允许量较大,故可不经分离或掩蔽直接测定锰矿中的铁。也可应用于铁矿中铁的测定。
Potassium dichromate volumetric method for the determination of iron, due to the addition of a large amount of mercury salts, pollute the environment. In recent years, many workers have devoted themselves to the experimental research on the determination of iron without mercury. Complexometric titration of iron sulfosalicylic acid is generally used as an indicator, but the end discoloration is not sharp enough. In this paper, iron (III) tribromide bromide (cetyltrimethylammonium bromide) was used as the indicator to titrate iron with EDTA, and the endpoint of titration was proved to be acute. The interference of coexisting ions was examined and experiments showed that 22 mg of manganese, 13 mg of aluminum, 10 mg of calcium, lead, zinc, arsenic, bismuth, 6 mg of magnesium, 5 mg of titanium, mercury, silver, 2 mg of copper, 1.6 mg of antimony did not interfere Determination. Due to the large allowable amount of manganese, the iron in the manganese ore can be directly measured without isolation or masking. It can also be applied to the determination of iron in iron ore.