Oxidation kinetics of ferrous sulfate over active carbon

Catalyzed oxidation kinetics of dissolved Fe2+ ions to Fe3+ over active car bon in concentrated H2SO4-FeSO4 solutions was studied with isothermal and i sobaric experiments carried out in a laboratory-scale pressurized autoclave . The experiments were performed at temperatures between 60 and 130 degrees C, and the pressure of oxygen (O-2) was varied between 4 and 10 bar. The k inetic results revealed that the oxidation rate was enhanced by increasing the temperature and pressure and that the catalytic and noncatalytic oxidat ions proceed as parallel processes. A rate equation was obtained for the ca talytic oxidation process, based on the assumption that the oxidation of Fe 2+ with adsorbed oxygen is rate determining. The rate equation for the cata lytic oxidation has the simplified form r = k " c(Fe)c(O) (0.5)(K-O" c(O)(0 .5) + 1) where c(Fe) and c(O) are the concentrations of Fe2+ ions and disso lved oxygen, respectively, and k " and K-O" are experimentally determined k inetic parameters. The total oxidation rate was simulated by including a pr eviously determined rate equation for the noncatalytic oxidation into the g lobal model, from which the kinetic parameters of the catalytic oxidation r ate were determined. A comparison of the model fit with the experimental da ta revealed that the proposed rate equation is applicable for the predictio n of the Fe2+ oxidation kinetics in acidic ferrous sulfate solutions.