Synthesis and characterisation of mesoporous silica phases containing heteroatoms, and their cation exchange properties. Part 3. Measurement of distribution coefficients for uptake of 137-Cs, 89-Sr and 57-Co radioisotopes

Well characterised tunable [1] MCM-41 phases with differing pore structures and containing aluminium, boron and zinc heteroatoms were described in Part 1 [2] to this series. Part 2 [3] illustrated that representative phases exhibited cation exchange selectivity. This part of the series studied the ability of 27 of the phases to take up the environmentally harmful radioisotopes of caesium, cobalt, and strontium, assessed by the measurement of distribution coefficients. Measurements were made in deionised water to simulate ground waters, with 0.1 M HNO3, 0.1 M NaNO3, and 0.1 M HNO3/NaOH solutions, chosen as nuclear waste simulants. In addition the effect of sodium tetraborate and tri-sodium citrate (10−3 to 10−6 M) on 57-cobalt uptake was studied. These additives were chosen as relevant to decommissioning/general decontamination (citrate) and Boiling Water or Pressurised Water reactors (borate) encompassing their potential to form complex ions with elements such as cobalt