Comparative study of oxygen/ozone mixtures on the electrochemical behaviour of different metals

VIERA, M; FERNÁNDEZ LORENZO DE MELE, M; VIDELA,H

JOURNAL OF APPLIED ELECTROCHEMISTRY

SPRINGER

Año: 2001 vol. 31 p. 591 - 598

0021-891X

The effect of dissolved ozone on the electrochemical behaviour of heat exchanger structural materials (carbon steel, stainless steel, copper, 70:30 copper?nickel, aluminium brass and titanium grade 1) was studied to evaluate the possibility of using ozone as sole biocide in cooling water treatment. With this purpose, voltammetric and open circuit potential (OCP) against time measurements at different ozone concentrations between 0.1 and 1.2 ppm were made. Results show different electrochemical responses according to the metal characteristics and the solution composition. First, the passivity of titanium and stainless steel was not affected by ozone. A linear OCP against log time relationship was found for titanium, suggesting the growth of a barrier film in both O2 and O2/O3 solutions. Mild steel does not passivate in synthetic cooling water either with O2 or O2/O3 in the solution. In the presence of ozone the breakdown of passivity is facilitated and makes the repassivation difficult. Ozone enhances the dissolution of Cu2O and the formation of Cu(II) species leading to less protective films. Both processes are strongly influenced by the pH. Finally, the dissolution of aluminium brass is higher than that of copper or copper?nickel.