Obtaining of purified solutions of sodium hydroxide for synthesis of ferrates(VI)

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

“…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.…”

“…Otherwise, the yield and purity of the target product will be significantly reduced. The treatment of concentrated alkalis with a flow of direct electric current, offered in [11] and adapted for Fe(VI) technology [9], allows reducing the content of heavy metal impurities to a safe level. To eliminate the negative effect of inorganic and organic compounds, which are capable of interacting with the target product, it has been offered to use strong oxidizers (О 3 , Н 2 О 2 ), which do not contaminate the alkaline solution with the products of redox reactions [2,5].…”

“…Ferrates solutions were prepared in two ways -by hypochlorite and electrochemical methods represented in [5,7,9,12] ), made of cast iron and steel of various grades, which composition is determined by ARL 3460 Optical Emission Spectrometer (Switzerland). The polarization of the electrodes was carried from direct current source B5-47 (Russia) to control the amount of electricity at constant current integrator IPT-1 (Belarus).…”

“…Solutions purification from precipitation and suspended particles was performed under vacuum using a Buchner funnel and Bunsen flask with filters made of polymer materials that are stable in solutions, which contain ferrates of alkali metal hydroxides. If necessary, mother liquors were treated with a flow of direct electric current to remove heavy metal compounds [9,11].…”