Removal of Radioactivity by
Ion-Exchange
H.  GLADYS  SWOPE
Chemical Engineering Division
Argonne National Laboratory, Lemont, Illinois
The use of ion-exchange resins may be of considerable value to
industries and hospitals for the removal of radioactivity.
The general handling of radioactive wastes at this Laboratory was
described in a paper presented at the Eighth Purdue Industrial Waste
Conference (1). The wastes from laboratory drains in buildings in
which there is radioactivity discharge to retention tanks. These wastes
are monitored and those over-tolerance are sent to the Waste Processing
Group, the others discharge directly to the Laboratory Waste Treatment Plant.
The experiments reported here have shown that of the cation resins
which are available today only those of the polystyrene divinyl benzene
sulfonic acid type are satisfactory for good removal of radioactivity.
These have a high capacity over a wide pH range, and are stable
towards acids, bases and organic solvents. After normal exhaustion of
the resin, i.e., breakthrough of calcium and magnesium, the resin is
effective in removing 65 to 75 percent of the total beta activity in the
feed from mixed fission product activity. Fission product analysis of
the effluents after passage through cation columns have shown that
strontium and rare earths were removed even after breakthrough of
calcium and magnesium. Ruthenium and cesium leaked before resin
exhaustion.
To verify and to try to find an explanation for the removal of radioactivity after hardness breakthrough, an experiment was run in which
mixed fission products were passed in parallel through columns containing sodium, calcium, magnesium and iron forms of the resin. These
results indicated that when tap water was at pH 2.5 the sodium form
of the resin removed more activity prior to hardness breakthrough than
any of the other three forms of the resin. After hardness breakthrough
the decontamination with the sodium form dropped below that for the
other forms. An important point to note is that the iron form of
the resin did not remove strontium90. When the tap water was at
pH 7.0, best results for total beta decontamination were obtained with
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