Cm(III) sorption by silica: effect of alpha hydroxy isobutyric acid

Abstract

Sorption of Cm(III) on silica surface from aqueous solutions of varying pH was investigated in absence and presence of alpha hydroxy isobutyric acid (HIBA) by employing batch sorption and surface complexation modeling (SCM). Cm(III) sorption on silica increased with the pH of the suspension and remained constant above pH∼6. With increase in HIBA concentration, the sorption edge shifted to higher pH. The effect of addition order of HIBA and Cm(III) on the sorption was studied and higher shift in sorption edge, as compared to binary system, was observed when HIBA was added to silica suspension prior to Cm(III). The sorption data could be satisfactorily explained by SCM in all the systems. The results have been compared with that reported earlier on the effect of HIBA on sorption behaviour of Eu(III) by silica. Further, the use of small organic molecules as model compounds of humic acid (HA) has been evaluated by comparing the influence of HA and HIBA on sorption of Cm(III) on to silica.

Sorption of Eu(III) on quartz at high salt concentrations

“…On the other hand, trivalent lanthanides, and more precisely, Eu has been selected as adsorbing solute of interest for the adsorption studies. This trivalent lanthanide cation is often used as a proxy for the radionuclides Am and Cm, which constitute an important fraction of the minor lanthanides/actinides present in the high-level liquid waste generated during the reprocessing of spent nuclear fuel 13 .…”

“…Consequently, a reliable understanding of their behaviour in contact with surfaces is crucial whenever retention processes are to be taken advantage of in the Safety Case for a given repository. Extensive studies have been carried out on the uptake of trivalent actinides onto mineral surfaces under different conditions [13][14][15][16][17][18] , but a study for high salt content on silica minerals is missing. In Germany and some other countries (Canada, USA, etc.)…”