A vas transzpasszív oldódásának vizsgálata erősen lúgos közegben

A dolgozatban egy speciális, ferrát-ionok előállítására alkalmas mérőberendezés összeállításáról esik szó. A berendezésen végzett elektrokémiai mérések segítségével vizsgálhatók a rendszeren lejátszódó folyamatok

Investigation of the transpassive electrochemical dissolution of Iron-based electrodes in highly alkaline media

INST: L_200Electrochemical ferrate synthesis was performed using a special-made cell. A comperative study of two Iron-containing electrodes was executed. The electrochemical processes occuring during the synthesis were investigated. The effect of some conditions (temperature) on the synthesis was also examined. The time-dependence of the processes was also investigated and compared in case of the two electrodes

Where do ferrate ions form? A dual dynamic voltammetry study

One of the most effective methods to produce ferrate ions (FeO42–) is electrochemical synthesis. During the transpassive anodic dissolution of iron, the formation of ferrate ions and the evolution of oxygen occur simultaneously, and only the sum of the currents generated by the two processes can be observed in the voltammetric curves. Products of the above process have been investigated in 45 % (m/m) aqueous NaOH solutions by using the dual dynamic voltammetry (DDV)&rotating ring-disk electrode (RRDE) method (i.e., applying dynamic potential programs to the disk and the ring electrodes of the RRDE disk electrode and the RRDE ring electrode simultaneously) combined with spectrophotometric measurements. Fe disk/Pt ring and Pt disk/Pt ring RRDE tips were used in the voltammetric experiments. The electrode potential regions where ferrate ions and oxygen are forming could effectively be identified. The results imply that, under the applied experimental conditions, the oxygen evolved at the disk cannot be reduced at the ring. This can be explained by the fact that elemental oxygen practically does not dissolve in concentrated aqueous sodium hydroxide solutions due to the “salting-out effect”. By using the dual voltammetric method, it was also possible to determine the optimal potential range for the electrochemical production of ferrate ions in terms of charging efficiency. The latter quantity has an important impact on the economics of practical applications. The approach proposed in this study proved to be very promising for the simultaneous detection of different dissolution products