Catalytic Oxidation of Ferrous Ion in Acid Medium with Active Aeration Using Activated Carbon Doped with Transition Metals

摘要

In this study, the catalytic oxidation of Fe2+ to Fe3+ is carried out with active aeration using activatedcarbon doped with Au, Pt and Ru, as an alternative to traditional oxidative methods for itsapplication in the ferric acid leaching of copper sulfides. An impregnation of Au, Pt, Ru in bothgranular (2 mm) and powdered (38 μm) activated carbons (274 m2/g) was performed. Using standardsolutions (48 mg/L) of these metals in contact with 4 g/L of activated carbon, for 2 hours in a stirredbed. Then, 5.6 g/L of NaBH4 was added for 3 hours to reduce the metal. The solution was filtratedand analyzed valued by UV-Vis analysis, while the obtained solid was dried. The catalytic oxidationtests were carried out in a stirred bed with an air flow of 384 NL/h, with activated carbonconcentrations between 0.8 and 8 g/L, using FeSO4.7H2O (500 mg/L) at pH =1. In periodic solutionsamples, the total iron content and the dissolved transition metals were determined by atomicabsorption spectrophotometry, the Fe2+ content by permanganimetry and by UV-Vis withphenanthroline. The texture and dispersion of the metals in the carbons were determined by SEMEDS.Powdered activated carbon at 0.8 g/L achieves an oxidation of 13.4% of Fe2+ in 4 hours, whileactivated carbon with 0.8 % Au, Pt, Ru content reaches 18.1 %, 15.6 % and 16.9 %, respectively. At aconcentration of 8 g/L of activated carbon doped with Au, an oxidation of 90 % of Fe2+ is achieved.Granular activated carbon with 0.8 % Au (8 g/L) achieves an oxidation of 17.8 % Fe2+. The use ofcatalytic oxidation of Fe2+ with activated carbon doped with Au, Pt, Ru and air is a promisingalternative that could be applied industrially.