Oxidation and immobilization of iron and manganese by a fluidized bed reactor

An iron and manganese species immobilization technology was developed in a fluidized bed reactor (FBR) with a new fluidized media, immobilized iron oxide (namely FeO_x-30). The FeO_x-30 catalyst exhibited excellent performance as a catalyst for the oxidation of Mn^2 +. About 95% and 30% of the manganese species were immobilized on FeO_x-30 and silica sand in FBR, respectively. The oxidation rates of Fe^2 + and Mn^2 + and the immobilization efficiencies of iron and manganese oxides strongly depend on pH value. Usually during oxidization the pH values of the solution containing Fe^2 + must be above 7, and Mn^2 + must be above 9. During this study, large amounts of iron species leached from the surface of FeO_x-30 only when manganese was in the system. The surface of the FeO_x-30 became fragile in a single system. However, the removal of iron and manganese species simultaneously was better than only the removal of manganese in an FBR. In the binary system, the optimum pH condition for immobilization of both iron and manganese species was pH_i 9. The higher catalyst loading in the binary system led to a higher removal efficiency of iron and manganese.