Polarography of Ti. II. Studies of reversibility of Ti^III and Ti^IV in acid sulphate medium

Abstract

The polarographic reversibility of the Ti3+/Ti4+ couple has been discussed the conditions of reversibility have been established and confirmed by several polarographic techniques. The reversible waves, anodic or cathodic are due respectively to the oxidation and reduction of hydrated sulphate complexes, viz. . Irreversibility is due to the formation of some hydrolysed sulphate complexes.

Electrochemical kinetics of the Ti(IV)/Ti(III) couple in sulfuric acid

“…It can be seen that with increasing Na 2 SO 4 concentration, the peaks of forms B and C develop to the detriment of the peak of form A. 4 . Experimental (solid) and calculated (dashed) curves in SWV performed with forward and reverse scans.…”

“…However, few electrochemical studies on the kinetics of the Ti(IV)/Ti(III) couple in sulfuric acid exist. The first polarographic investigations [1,4] show a trend towards reversibility with increasing acid concentration and a more complex kinetic mechanism for the reduction of Ti(IV) than for the oxidation of Ti(III). More recently, some results obtained in a Ti(IV)-2 M H 2 SO 4 solution by voltammetry at a rotating amalgamated lead electrode and by cyclic voltammetry at the mercury drop electrode were reported [5,6].…”

Corrosion resistance and electrochemical behavior of building materials in the regeneration of nitric acid

“…The correlation between the corrosion rate of titanium and the hydrogen ion concentration leads to the conclusion that in nitric acid solutions the corrosion of passive titanium is limited by the rate of chemical dissolution of the passive film according to the equation [13] TiO2+2H + ~--~ Ti02++H20, according to which the corrosion rate of titanium must increase with increasing acidity and decrease with the accumulation of titanium dissolution products [ii]. The latter fact is used to explain the low corrosion rates obtained under laboratory conditions without frequent replacement of the solution, which has to be taken into consideration when applying such data to the real operating conditions of the equipment~ Thus, in the fractionation of nitric acid solutions containing chloride ions, stainless steels are subject to increased general and local corrosion in the upper part of the column, i.e., in media with low nitric acid contents in the presence of hydrochloric acid and molecular chlorine.…”

Determination of titanium by controlled-potential coulometry

“…Polarographic literature (4) indicates that the electrochemistry of the Ti(IV)-Ti(III) system is well defined in several supporting electrolytes. Of these, strong sulfuric acid (5)(6)(7)(8) was chosen for development of the controlled-potential coulometric procedure. This electrolyte is compatible with most titanium dissolution media (1, 6) and it forms stable solutions with most metals commonly associated with titanium.…”