Abstract
Pertechnetate anion sorption was investigated on modified bentonites. Mn-, Cr-, Sn-bentonites were prepared by ion exchange process to sorb radioactive pertechnetate ions. In the case of Mn-, Cr-bentonite the sorb amount of metal ion was 70–90% of the cation exchange capacity of the bentonite which is expected. Interestingly in the case of Sn-bentonite this amount was 1.42 times higher than the cation exchange capacity. On Mn-bentonite the sorption was 35% at pH 5. The removal of pertechnetate ions was 100% on Cr-, Sn-bentonites and the significant sorption was achieved below 650 mV/SHE.
Highlights
Long-lived low- and medium-level radioactive waste and spent fuel assemblies are difficult to store because fissile products can get into the environment
The Mn, Cr, Sn concentrations in modified bentonites were 7 × 10−4; 1.86 × 10−4 5.8 × 10−4 mol g−1, so 0.86 0.69 and 1.42 times of the cation exchange capacity was sorbed in bentonite, respectively
These modified bentonites were used for pertechnetate ion removal
Summary
Long-lived low- and medium-level radioactive waste and spent fuel assemblies are difficult to store because fissile products can get into the environment. Natural geological barriers do not bind anions from the fission products of 235U [1]. Among the fission products 99Tc is a β-emitter, has no stable isotope, has a half-life of 2.13 × 105 years. It is produced in medical diagnostic uses by the decay of 99mTc [2]. It is hard to bind, very little is known about its chemistry, but we can assume that it is similar to elements in a column VII B. Several methods can be found for the removal of 99Tc in most cases as pertechnetate ions such as ion exchange [3], reductive immobilization [4], adsorption [5], liquid–liquid extractions [6]
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