Studies On Stability And Kinetics Of Fe(Ⅵ) Compounds In Aqueous Solution

Ferrate(VI) is a new environmentally inorganic material, which has many purposes. It has promising applications in areas of wastewater treatment, organic synthesis and electrochemical power. Furthermore, ferrate(VI) is more likely to be a substitute of dry battery in 21st century. But the bad stability in aqueous solution largely makes its applications limited. Therefore, it is important to increase the stability of ferrate(VI). It is necessary to investigate the stability and find the stabilizers. In the article, we tracked and monitored the absorption of ferrate(VI) in aqueous solution with/without stabilizers by way of spectrophotometry. At first, we investigated the stability and kinetics of ferrate(VI) in NaOH solution.The factors for stability in aqueous solution were analysed. In addtion, the effects of many compounds on the stability of ferrate(VI) were examined, such as haloid compounds, Na2CO3, Na2HPO4.The paper discussed the factors which are initial ferrate(VI) concentration, alkalinity concentration, pH, temperature, type and concentration of additives. Furthermore, the mechanism of stability was analysed and discussed. The results showed that the decomposition of ferrate(VI) in aqueous solution is a first order reaction. The factors for stability mainly are the alkalinity concentration, initial ferrate(VI) concentration and temperature. We observed that the ferrate(VI) was one order of magnitude more stable in aqueous solutions with Iodate(A). Some compounds can make ferrate(VI) much stable under specific conditions, including KI, Na₂CO₃ and Na₂HPO₄. Besides, the yield and purity of ferrate(VI) are improved by adding KI during the preparation. However, KCl and KBr have no effect on the stability of ferrate(VI) in alkaline solution. The others can accelerate its decomposition, including Iodate(B), Na₂B₄O₇, NaHCO₃, K₃PO₄, CH₃COONa, (CH₃COO)₂Zn and CH₃COOK.