13.4 Solvent Extraction
205
The ionic compounds are not soluble in covalent organic liquids; the solvent
extraction of metallic ions, therefore, requires the presence of some substances,
which convert them into neutral soluble complexes. The use of organic complexing
agents such as 8-hydroxyquinoline, dimethylglyoxime etc., are in common use for
this purpose. This technique has been used extensively in radiochemical separation.
For example, separation of uranium and plutonium from the fission products in
reactor fuel elements has been successfully achieved by dissolving the fuel elements
in nitric acid, from which uranium and plutonium are separated by extraction from
a variety of solvents, such as tributylphosphate diluted with an inert solvent like
kerosene. Plutonium (in trivalent state) is extracted by washing the solvent phase
with an aqueous phase containing reducing agents such as ferrous ions, whereas
uranium is recovered by washing the organic phase with water.
13.5 Electrochemical Methods
The electrochemical method is nowadays used extensively because the contamination
by adsorption of micro-components from the solution is very small, moreover, it is
a very rapid method. The electrolysis may be carried out with or without the use of
a carrier. For example, the deposition of Silver-110 with or without the presence of
natural silver as a carrier, on a gold disk as a cathode, using ammonical solution,
can give about 99.9% yield. Thin sources, showing very little self-absorption, can be
prepared by this method.
The electrolysis can be performed in two ways. In the first, the metal can be
deposited on the cathode from the appropriate solution of its ions; for example, a
protoactinium source can be prepared by electrodeposition on various metal cathodes from a very dilute and slightly acidic fluoride solution. In the second method,
the species in the region of high pH, produced by the discharge of hydrogen ions
at a cathode, is precipitated in an insoluble form on to the cathode; examples are
lanthanides and actinides precipitated by hydroxide.
13.6 Volatilization and Distillation
Volatilization or distillation is often a quick method of separation provided the
radioactive materials to be separated have widely different vapor pressures. For example, Iodine-131 may be volatilized from a neutron irradiated samples of tellurium
oxide.
205
The ionic compounds are not soluble in covalent organic liquids; the solvent
extraction of metallic ions, therefore, requires the presence of some substances,
which convert them into neutral soluble complexes. The use of organic complexing
agents such as 8-hydroxyquinoline, dimethylglyoxime etc., are in common use for
this purpose. This technique has been used extensively in radiochemical separation.
For example, separation of uranium and plutonium from the fission products in
reactor fuel elements has been successfully achieved by dissolving the fuel elements
in nitric acid, from which uranium and plutonium are separated by extraction from
a variety of solvents, such as tributylphosphate diluted with an inert solvent like
kerosene. Plutonium (in trivalent state) is extracted by washing the solvent phase
with an aqueous phase containing reducing agents such as ferrous ions, whereas
uranium is recovered by washing the organic phase with water.
13.5 Electrochemical Methods
The electrochemical method is nowadays used extensively because the contamination
by adsorption of micro-components from the solution is very small, moreover, it is
a very rapid method. The electrolysis may be carried out with or without the use of
a carrier. For example, the deposition of Silver-110 with or without the presence of
natural silver as a carrier, on a gold disk as a cathode, using ammonical solution,
can give about 99.9% yield. Thin sources, showing very little self-absorption, can be
prepared by this method.
The electrolysis can be performed in two ways. In the first, the metal can be
deposited on the cathode from the appropriate solution of its ions; for example, a
protoactinium source can be prepared by electrodeposition on various metal cathodes from a very dilute and slightly acidic fluoride solution. In the second method,
the species in the region of high pH, produced by the discharge of hydrogen ions
at a cathode, is precipitated in an insoluble form on to the cathode; examples are
lanthanides and actinides precipitated by hydroxide.
13.6 Volatilization and Distillation
Volatilization or distillation is often a quick method of separation provided the
radioactive materials to be separated have widely different vapor pressures. For example, Iodine-131 may be volatilized from a neutron irradiated samples of tellurium
oxide.