Effect of chromium compounds on synthesis of alkali metal ferrates (VI)

Abstract

Кандидат химических наук, доцент Кафедра технологии неорганических веществ и экологии Украинский государственный химикотехнологический университет пр. Гагарина,

Usage of mother liquor recycling for the obtaining of Fe(VI) compounds

“…It has been established that the main impurities in the liquid phase are manganese and chromium oxoanions (MnO 4 2-, CrO 4 2-) ( Table 2). Table 2 The content of manganese and chromium oxoanions in the mother liquor after electrosynthesis These results do not go against the works [6,10,13], which inform about the inclusions of manganese and chromium in the crystalline ferrates prepared by electrochemical and chemical methods.…”

“…Therefore, in order to eliminate the negative effect of insoluble Co, Ni, Cr, Mn compounds, etc., contained in the sludge [10,13] and the transition of some its components (Cr, Mn) into the liquid phase, it is necessary to reduce the contact time of the latter with the mother liquor, for example, by means of periodic or continuous filtration.…”

“…However, this issue is not given enough attention. In the papers [8,9], devoted to the technologies of obtaining ferrates, a special role is assigned to the purity of the used alkali metal hydroxides, which is due to the use of very concentrated alkaline solutions (14)(15)(16) [5,10]. Otherwise, the yield and purity of the target product will be significantly reduced.…”

“…In addition, the use of 11 M potassium hydroxide solutions for recycling, proposed in [8], does not meet the requirements for modern technologies, in which it is recommended to use solutions with a higher KOH concentration [2, 5, 10]. Moreover, it can be assumed that such low values of the yield of the target product, obtained in [8] are also due to the accumulation of soluble and insoluble heavy metal compounds in the system, the formation of which is justified in [10,13].…”