Separation Of Lanthanides/ F-Block Chemistry

Separation of LanthanidesThe lanthanides are trivalent and are almost identical in size, their chemical properties are almost identical.The separation of one metal from another is as difficult as the separation of isotopes.Different method used are1. Precipitation2. Thermal Reaction3. Fractional Crystallization4. Complex Formation5. Solvent Extraction6. Valence ChargeSeparation MethodsPrecipitationPrecipitating agent is used for separationWith a limited amount of precipitating agent the substance with the lowest solubility is precipitated most rapidly and most completely.If ions are added to the solution of lanthanide nitrates, the weakest base Lu(OH)3is precipitated 1stand the strongest La(OH)3last.If the partial separation takes place, precipitates can be dissolved and the process is repeatedThermal reactionIf the nitrates are fused (treated at high temperature, calcined) a temperature will be reached when least basic lanthanoid forms the oxides. The mixture is then washed with water.Oxides being insoluble remains. It is reconverted to nitrate and process is repeated.Mixture nitrate Lu2O3Lu2O3+ HNO3Lu(NO3)3RepeatedCalcine SeparateFractional CrystallizationFractional crystallization of simple salts such as nitrates, sulphates, bromates, perchlorates etc. has been frequently used for the separation of lanthanides.Fraction crystallization is a process in which mixed compounds are dissolved in solvent, heated and then gradually cooled, so that each fraction crystallizes and is removed from the solution in pure formThe