The Effect of pH on the Uptake of Radioactive Isotopes from Solution by a Soil
- D. W. Rhodes
The reactions with natural earth materials of fission products and plutonium are of current interest in the field of atomic energy waste disposal and soil chemistry.
Solutions containing less than 1 × 10-9 moles per liter of selected radioisotopes were equilibrated with samples of a calcareous subsoil. The uptake of these radioactive isotopes by the soil was measured as a function of pH. The uptake of Cs137 was not affected appreciably by varying the pH between 4 and 10. The maximum uptake of Sr90 occurred at about pH 10 and decreased rapidly as the pH was lowered. The radioisotopes Pu239, Ce144, Zr95, -Nb95, Y91, and Ru106 exhibited a maximum uptake between approximately pH 4 and pH 8. Above pH 8 a region of reduced uptake occurred and persisted up to at least pH 11 for most of the polyvalent radioisotopes.
The addition of high concentrations of sodium salts to the solution inhibited the uptake of both Cs137 and Sr90 by soil. A relatively small concentration of phosphate (0.01 M) added to the system was found, in effect, to nullify the interference of sodium ion with the uptake of Sr90, but the phosphate ions had no apparent influence on the uptake of Cs137.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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