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本文研究了萃取过程中Fe(Ⅲ)—phen体系光还原规律。实验发现在散射光中Fe~(3+)—phen络合物发生显著的光还原反应,向体系中加入EDTA可阻止Fe~(3+)-phen的光还原,但并不影响NH_2OH·HCI对Fe~(3+)还原为Fe(Ⅱ)的反应。少量还原剂(S_2O_3~(2-))存在时不影响铁价态测定。本方法能用于Fe(Ⅱ)(Ⅲ)—EDTA体系的铁价态测定。
In this paper, the photoreduction of Fe (Ⅲ) -phen system during extraction was studied. It was found that there was a significant photoreduction of Fe ~ (3 +) - phen complex in the scattered light and the addition of EDTA to the system prevented the photo - reduction of Fe ~ (3 +) - phen but did not affect the NH_2OH · HCI Fe (3 +) reduction to Fe (Ⅱ) reaction. A small amount of reducing agent (S_2O_3 ~ (2-)) does not affect the iron state determination. The method can be applied to the determination of iron valence state in Fe (Ⅱ) (Ⅲ) -EDTA system.