Studies on Batch Sorption Methodologies: Eu Sorption onto Kivetty Granite

Six different methodological features of the batch sorption experiment were investigated using ¹⁵²Eu, Kivetty granite, saline water with initial pH of 8.5, 9 and 10, Eu]tot=5·10^-7M, S:L = 1:20, pre-washing of granite, occasional shaking, centrifugation, wall sorption correction with separate tubes. This gave final Rd= 8.3±2.1, 7.3±2.6 and 8.6±3.7m³/kg at 6 months for each pH, respectively. Then Eu]tot and S:L were varied, filtration was compared with centrifugation, separate tubes for wall sorption was compared with wall desorption, pre-washing of granite was compared with no washing and two shaking methods were compared. Two of the investigated methodological features gave too large apparent Rd due to: 1) filter sorption, and 2) low radiotracer concentration, leading to detection problems.