Comparative study of Eu and U sorption on cementitious materials in the presence of organic substances

Abstract

A comparative study of the sorption behavior of europium, a chemical analogue of trivalent actinides, and uranium was performed on hydrated cement paste (HCP) CEM I and calcium-silicate-hydrates (CSH) phase. Kinetic experiments proved that Eu sorption is faster than that of U depending on the phase ratio L/S and the sorption material, whereas EDTA has no significant effect. Same conclusions can be made for equilibrium experiments with HCP and U while with Eu EDTA clearly influenced the distribution ratio Rd with sorption reduction factor (SRF) below 0.5. Uranium sorption on CSH compared to HCP is higher with SRF above 1.2.

Time-Dependent Retention of a Mixture of Cs(I), Sm(III), Eu(III) and U(VI) as Waste Cocktail by Calcium Silicate Hydrate (C-S-H) Phases

“…Especially for Eu(III) and Sm(III), it can be clearly seen that the immobilisation on Circosil ® is the preferred retention mechanism compared to wall adsorption and classic precipitation in the binary system without adsorbent material. In the literature, wall adsorption of Eu(III) [26,44] and U(VI) [44,51] on PP tubes in the presence of C-S-H phases and hydrated cement paste was also investigated. While Tits et al [26] observed wall adsorption <1% for Eu(III), the results gained by Burešová et al [44] and Pointeau et al [51] are similar to this study.…”

“…In the literature, wall adsorption of Eu(III) [26,44] and U(VI) [44,51] on PP tubes in the presence of C-S-H phases and hydrated cement paste was also investigated. While Tits et al [26] observed wall adsorption <1% for Eu(III), the results gained by Burešová et al [44] and Pointeau et al [51] are similar to this study. They found only a small amount of U(VI) adsorbed on the wall (<2 or <5%, c(U(VI)) = 4•10 −9 − 7•10 −8 mol•L −1 ).…”

“…For Eu(III), the adsorbed amount was 6.5%-100% depending on the solid-to-liquid ratio and the present adsorbent material. Burešová et al [44] explained it by the adsorption of cement or C-S-H colloids on the wall where Eu(III) or U(VI) is immobilised. The same observation was made in this study as even after centrifugation, small particles were visible in the upper part of the liquid phase and on the tube wall.…”

“…For Eu(III), and Sm(III) as chemically very similar rare earth elements (and as homologues to Am(III) and Cm(III)), three retention mechanisms on cementitious materials or C-S-H phases are proposed in the literature: adsorption, incorporation and precipitation [14,26,[44][45][46][47][48]. Each of these studies observed high up to quantitative retention for both elements.…”

Evaluation of Physico-Chemical Characteristics of Cement Superplasticizer Based on Polymelamine Sulphonate

“…In assessing the long-term safety of radioactive waste repositories, the interaction between radionuclides and cement-based barrier materials is of great interest [6][7][8][9][10]. The interplay is dependent on both the nature of the radionuclides and the type of cement [10][11][12][13][14]. The retention or migration of radionuclides from the disposal facility is related to several factors specific to a cementitious backfill, including a significant pH gradient, temperature, electrolyte composition, presence of organic compounds, redox potential and ionic strength [6,[8][9][10]14].…”