The Solubility and Sorption of Radium and Tin in a Cementitious Near-Field Environment

Abstract

The solubility and sorption of radium and tin have been studied for a cementitious near-field environment.The solubility of radium was observed to be greater than 10-7 M, even with the addition of iM sulphate to the cement equilibrated water. The values of RD for radium varied from 102 to 103 ml g-1 for the cement types and initial radium concentrations studied.The solubility of tin was observed to be about 10-4M for a range of cement equilibrated waters above tin oxides and metallic tin. The solubility of tin was observed to increase with pH. Tin solubilities were not affected by the redox conditions.Tin was present in a range of particle sizes in the sorption studies. A value of RD of 104 ml g-1 was observed for tin species less than 0.45nm.

Thermodynamic data for the solubility of tin(IV) in aqueous cementitious environments

“…Thus, the thermodynamic data obtained from the well-defined systems used in the present investigations are able to predict Sn concentrations measured in much more complex, real cement porewaters. Similar Sn solubilities, 10 −7 -10 −5 M, have been measured by Bayliss et al [14,15] in the presence of cement equilibrated water. However, it was not possible to recalculate these experiments as the final Ca concentrations have not been determined in [14] and [15].…”

Geochemical Data Package for Performance Assessment Calculations Related to the Savannah River Site

“…Ra 5x 10 -5 10 -6 5x 10 -5 10 -6 5x 10 -5 10 -6 RaSO 4 is the controlling solid (1, 14). Bayliss et al (1989) Bradbury and Sarott (1995) and as described in Section 4.2, the solubility concentration limits values in the Aged Concrete (3 rd Stage) were set to an order of magnitude higher (more soluble) than those in the Moderately Aged Concrete (2 nd Stage). This same approach to assigning solubility concentration limits values to the 3 rd Stage was used by Bradbury and Sarott (1995).…”

Geochemical Data Package for Performance Assessment Calculations Related to the Savannah River Site

“…Thus, according to Allard et al (1984) and Ewart et al (1992) RaSO 4 is the controlling solid (1, 14). Bayliss et al (1989) Assumed solubility controlling phase are hydroxide/hydrous oxides for Th, Zr, Pu and hydroxycarbonates for Pb. The following is from (2) and was conducted by adding Th(IV) to water equilibrated with concrete and pH adjusted: solubility ranged from 1e-8 M to 4e-9 M as pH increased Bradbury and Sarott (1995) and as described in Section 4.2, the solubility concentration limits values in the Aged Concrete (3 rd Stage) were set to an order of magnitude higher (more soluble) than those in the Moderately Aged Concrete (2 nd Stage).…”