Anodic dissolution of chromium in acidic sulphate solutions

✍ Scribed by Masaru Okuyama; Masahiro Kawakami; Koin Ito

• Publisher: Elsevier Science
• Year: 1985
• Tongue: English
• Weight: 784 KB
• Volume: 30
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(85)80124-9

✦ Synopsis

Active anodic dissolution of chromium in acidic sulphate solutions was investigated by using the rotating ring-disc electrode (n-de). Chromous ions dissolved from the chromium disc could be collected on the gold ring electrode by oxidation to chromic state. The empirical collection number was estimated to bc 0.052, althqugh the theoretical value was 0.24. The current ofactive an&c dissolution gave two Tafeel regions with the Tafel slope of 0.03 and 0.12 V decade-' in the lowerand higher current density regions, respectively. The pH value of the solutions did not affect the dissolution current. The increase in sulphate anion concentration reduced thecurrent in the highercdregion. In order to interpret the experimental results on the activedissolution ofchromium. a new mechanism was proposed, which was similar to the Bock& mechanism in the case of the iron dissolution. Passivation of chromium was found to take place without relation to active dissolution. It was concluded that the passivation wasattributable to the formation of the trivalent chromium oxide such as CrO(OH).