Co-Precipitation of Metal Ions during Ferrous Hydroxide Gel Formation
It has been found that metal ions in solutions are copreeipitated with Fe(OH)2 gel and are removed quite satisfactorily from the solutions. When Fe2+ solutions containing divalent metal ions such as Mg2+, Mn2+, Co2+, Ni2+, Zn2+ and Cd2+ are brought to pH≥10, these metal ions are incorporated into ferrous hydroxide precipitates. Rapid oxidation of the precipitates, for example, by a H2O2 solution, leads to the formation of cation-substituted δ-FeOOH which is ferrimagnetic at room temperature (1) and stable against elution of the metal ions by washing. Thus, the metal ions incorporated in the ferrimagnetic solids are easily removed from the solutions with the aid of high gradient magnetic field. Residual concentrations of the metal ions in the solutions were of the order of 0.1 to 0.01 ppm depending on the coprecipitation and oxidation conditions.
KeywordsResidual Concentration Metallic Copper Ferrous Hydroxide Metallic Mercury High Gradient Magnetic Field
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