2 research outputs found
Nonreversible Immobilization of Water-Borne Plutonium onto Self-Assembled Adlayers of Silanized Humic Materials
The
objective was to study plutonium partitioning between immobile
and mobile humic materials at the water–solid interfaces. Immobilization
of the humic materials on solid supports was performed in situ using
self-adhesive silanized humic derivatives. The presence of the humic
adlayers on solid supports was shown to significantly enhance Pu sorption
and its retention under both steady state and dynamic conditions.
While plutonium may exist in multiple oxidations states plus colloidal
forms, the major thrust in this work was to study the behavior of
most mobile – the PuO<sub>2</sub><sup>+</sup> form in dilute
solutions. The values of the plutonium partition coefficients (<i>K</i><sub>d</sub>) between water and humics-coated silica gels
after 10 days exposure reached 1.6 × 10<sup>4</sup> L·kg<sup>–1</sup> at pH 7.5 under anaerobic conditions with a total
plutonium concentration of 1.2 × 10<sup>–8</sup> M exceeding
those for the uncoated SiO<sub>2</sub> (6.3 × 10<sup>2</sup> L·kg<sup>–1</sup>). Column tests showed substantial sequestration of
water-borne plutonium (up to 73%) on the humics-coated silica gels.
Remobilization experiments conducted under batch conditions at different
pH values (3.5, 4.5, 7.5) showed that no more than 3% of the sequestered
Pu was remobilized from the humics-coated silica gels by treatment
with dissolved humic materials at environmentally relevant pH of 7.5.
Consequently, silanized humic materialas can be seen as both molecular
probes and as potent candidate materials for scavenging mobile Pu
from an aqueous phase