| Some factors influencing the formation of the green solutions from ferrate solutions were investigated. A qualitative study of the effects of temperature, alkalinity, and concentration of the ferrate ion on the formation of the green solution was made under carefully controlled conditions. The nature of green solution was determined by means of chemical analysis , atomic absorb spectrum (AAS), infrared spectrum (IR), XRD and Mossbauer.Cyclic voltammetric (CV) curves for the redox couple of ferrate (VI)/ferrate(III) were measured using stationary glass carbon (GC) electrode. The studied systems were the solutions of Na2FeO4 and NaFeO2 in 16M NaOH, with the concentration range of 0.015-0.06 and 0.01-0.025M respectively, and the solid mixtures of K2Fe04 or KFeO2 and colloidal graphite, adhered to the surface of the GC electrode in 16MKOH. The aim of this work was to find the experimental conditions to describe both cathodic and anodic current peaks corresponding to the reduction and formation of FeO42- in CV curves simultaneously, with GC electrode which has a wide electrochemical window, to measure the solid and liquid samples of ferrate(VI) and ferrate(III) in concentrated KOH or NaOH solution.The kinetics of quick electrolysis was investigated. Quick electrolysis condition could be built when using an iron anode that has larger specific surface area and an ionic membrane electrolytic cell in which an anode lying between the two cathodes. Under the condition, the anolyte of Na2FeO4 in the concentration range from 0.39-0.47mol/L could be obtained by electrolyzing the iron anode in 16mol/LNaOH solution during 4-6h in the temperature of 308K.The main conclusions follow as below.(1)The higher the temperature, the smaller the alkalinity, the time, which was used to form the green solution, was shorter. It was discovered that the time, which was used to form the green solution, decreased with increasing the temperature and with decreasing the alkalinity. The initial concentration of FeO4 22 in aqueous solution exerted a marked influence upon the formation of the green solution. The greensolution was not obtained when the concentration of FeO42"was below O.lmol/L. The visible absorption spectrum of green solution is charactered by two bands at about 240nm and 420nm. The ratio varied from 10.599 to 6.824;for Mn(V) this ratio is5.6547;for Fe(IV) this ratio is 10.58~10.18.The atomic absorb spectrum and the visible absorption spectrum of green solution showed that the presence of Mn(V) was doubtless and Fe(IV) was also existed in the green solution. Chemical analysis confirmed the conclusion. But when K+ was added, that method was not available. The thermal decomposition process of a hexavalent iron compound, KiFeO4, was studied by means of XRD and Mossbauer. Green product was obtained by the decomposition above 250 . By the X-ray diffraction technique, the green product was also confirmed to be a single phase of KFeO2.The product showed a paramagnetic Mossbauer spectrum at 298K, with an isomer shift and quadrupole splitting of 0.26050mm/sec and 0.071501 mm/sec respectively; it also showed a magnetically-split six-line spectrum with an internal magnetic field of 506.586kOe.These Mossbauer parameters are charateristic of the Fe3+ state. The intermediate valence states, Fe5+ or Fe4+, were not observed during the decomposition process, and so it was concluded that the Fe6+ ions in K^FeCU were reduced directly to Fe + ions.(2) By the cyclic voltammetric study of the solutions of Na2FeO4 and NaFeO2 in 16M NaOH and of the solids of K2FeO4 and KFeO2 in 16M KOH with GC electrode, we have demonstrated that the glassy carbon electrode is a more proper working electrode than that of iron and platinum for studying the electrochemical characteristics of the redox couple of ferrate(VI)/ferrate(III) in alkaline solution. The anodic and the cathodic current peaks on the cyclic voltammetry curves, at 0.7~1.0V and at 0.15-0.2V vs. Hg/HgO/16M NaOH respectively, are two conjugated peaks corresponding to the formation and r...
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