Inhibitoren der Korrosion (14). pH-Wert-Änderungen in Suspensionen von Eisen in 0, 2 m NaCl-Lösungen unter den Bedingungen der Sauerstoffkorrosion

Corrosion inhibitors (14) pH variations in suspensions of iron in 0.2 m NaCl solutions under conditions of oxygen corrosion The pH of iron suspensions is deter-mined in a suitable apparatus under varying reaction conditions. The results are as follows:

• 1 In a suspension of 25 grs of carbonyl iron powder in 100 ml of pure water there is no pH variation, neither under nitrogen nor under oxygen.
• 2 When 25 g of carbonyl iron powder are introduced under 100ml 0.2 m NaCl solution, the pH value rises from 6.60 to 9.4-9.5 within three to eight minutes.
• 3 Determination of the dissolved Fe(OH)₂ quantity and conversion of the latter to pH units reveals, that the pH rise is due to (a) an exchange of OH^?-ions for CL^?-ions at the boun.