Synthesis, characterisation and uptake of radionuclides by Crystalline Silicotitanates(CST)

Crystalline Silicotitanate (CST) inorganic ion exchanger, with a sitinakite structure is candidate material for remediation of aqueous nuclear waste streams. The synthesis of Crystalline Silicotitanate and Nb-substituted Crystalline Silicotitanate (Nb-CST) was carried out under hydrothermal conditions and were characterised using XRD, SEM, surface area techniques. Batch experiments were carried out to study the kinetics of uptake of 137Cs and 90Sr, to estimate the distribution coefficients (Kd) for the above synthesized CST and Nb-CST samples from actual radioactive waste solutions. The DF values for uptake of Cs and Sr for Nb-CST after 24 hours of equilibration was 355 and 136 whereas for CST it was found to be 40 and 176 respectively. The Kd values for uptake of Cs and Sr for Nb-CST after 24 hours of equilibration was found to be 35490 ml/g and 13500 ml/g respectively whereas the Kd values for uptake of Cs and Sr for CST was found to be 4025 ml/g and 17525 ml/g respectively.(author)