EDTAによる塩化第二鉄液 (腐食液) の疲労測定 (第3報)

主として迅速滴定法のための改善点について

抄録

To make the rapid fatigue measurment of ferric chloride solution, it was intended in this study to restrain the formation of precipitation of Fe(OH)₃ in diluting and to improve the imperfection of the separation of Fe and Cu, the inconvenience of requiring much time for separation, and the complexity of the operation because of the disagreement of pH values in titrating Fe³⁺ and Cu²⁺.
I In titrating Fe³⁺, the pH value range was examined within which the end-point of the salicylic acid as chelatometric metal indicator was not given any effects and the precipitation of Fe(OH)₃ was not formed.
II In order to make the efficient separation of Fe³⁺ and Cu²⁺, the column chromatography was applied in this experiment, which makes Fe-EDTA formad by titrating Fe³⁺ directly absorbed to a strong basic ionexchangable resin and separate the Cu²⁺ from the solution.
III If the Cu²⁺ is titrated near about at pH 8, the precipitation of Cu(OH)₂ is resulted. Therefore a chelatometric metal indicator for titrating in the range of acidity was used and the pH value in this case was measured.
From the experiments above, the following conclusions were obtained. At I way, in pH values between 2 from 2.5, the possibility was found.
At II way, the use of N/100 HCl as an elute enabled to keep the error within 3% and elute 5 or 6 ml/minute.
At III way, the chelatometric metal indicator, 1-(2-Pyridylazo)-2-naphthol (PAN) 0.1% alcohol solution, made the titration possible between pH 2 from 2.5.