K. Nishimaki et al., SORPTION AND MIGRATION OF RADIOIODINE IN SATURATED SANDY SOIL, Journal of Nuclear Science and Technology, 31(8), 1994, pp. 828-838
Using I-125 as tracer, the migration of iodide and iodate in a solvent
flowing steadily through saturated sandy soil was examined in column
experiment and analyzed theoretically, with particular reference to th
e effect of differences in pH value. Runs at pH 3, medial pH and pH 10
were performed to determine breakthrough data from radioactivity meas
urements on the effluent solution. The results obtained from column ex
periments indicated that, for the same pH, sandy soil sorbed iodate ((
IO3-)-I-125) more strongly than iodide (I-125(-)), and that, for the s
ame chemical form, more effective sorption is shown at lower than at h
igh pH. This indicated that the sorption behavior of iodine in sandy s
oil depended significantly on their chemical form and on pH-i.e. the h
ydrogen ion concentration in the influent solution. The strong sorptio
n of iodate under medial pH and pH 3-evidenced by the breakthrough dat
a-was simulated numerically, based on mathematical expressions represe
nting a combination of instantaneous (equilibrium) and limited-rate (n
on-equilibrium) sorption processes. Unknown parameters incorporated in
the model were determined by a procedure of fitting the mathematicall
y derived curves to the observed plots for different experimental cond
itions, as a result of which good agreement was obtained of the calcul
ated curves with the observed breakthrough plots.