Batch experiments of Cs, Co and Eu sorption onto cement with dissolved fibre mass UP2 in the liquid phase

The potential effects of alkaline degradation products of the fibre mass UP2 on metal sorption onto fresh and degraded cement have been investigated. For this purpose, crushed cement have been leached to support material for the subsequent batch sorption experiments. Alkaline leaching of UP2 were also made, which gave leaching solutions of 30 ppm DOC after 300 days. These solutions were used in the batch experiments. Continued leaching shows that even higher concentrations can be expected: 45 ppm DOC in the leaching with a low-alkaline (pH 12.5) artificial cement pore-water and 150 ppm DOC with a high alkaline (pH 13.3) artificial pore-water. Batch sorption experiments with 134Cs and 60Co show no effects on metal sorption onto leached or fresh cement when the 30 ppm DOC leaching solutions of UP2 were used as liquid phase. The measured Rd values were 10-3 m3/kg for Cs and in the range of 0.03-0.1 m3/kg for Co. Separate experiments with other organics ligands were also made: EDTA, ISA and citric acid with maximum concentrations of 500, 300 and 300 ppm DOC, respectively. Also here no effects on Cs and Co sorption onto leached and fresh cement were established. Batch experiments of 152Eu were not successful since results were above detection level of about 2-3 m3/kg. The addition of the aforementioned 30 ppm UP2 leaching solution or the other organic ligands did not affect the detection level. Measurements of background concentrations of total Eu show a peculiar result of Eu apparently increasing in batch experiments with cement to final values of about 5-10 nM. The underlying reason for this effect, whether real or artificial, could not be established. Background concentrations of Th were about 1 nM in both cement and blank samples. Background concentrations of Zr were about 100-700 nM in both cement and blank samples, the high values were measured acidic blanks, which suggests either acidic leaching from tube walls or contamination from the acid itself. No effects from the leaching products of UP2 or the other organic ligands on the background concentrations of Eu, Th and Zr could be confirmed.