Microwave-assisted Synthesis of Hydrated Sodium Uranyl Oxonium Silicate

摘要

Twenty five years ago,some of us devoted many efforts to the synthesis of new uranyl complexes in chloride,sulphate and acetate acid media [1-6].Soon,we worried about the destiny of the mother-waters and attempted to minimise their impact developing solar photo-reduction procedures to enhance the recovery of products [7].Now,we are following a more benign strategy for such synthesis using microwave (MW) irradiation.MW-assisted synthesis,based on the concepts of dielectric heating and of the resonance absorption due to rotational excitation,gives rise to conditions generally much faster,cleaner and economical than the conventional methods [8].This communication presents a 20 minutes synthesis of hydrated sodium uranyl oxo-nium silicate from uranyl acetate by reaction with a diluted sodium silicate solution under MW irradiation.An integrated analysis of the reaction product using X-ray diffraction analysis,scanning electron microscopy,infrared spectroscopy and ther-moanalysis demonstrates the presence of hydrated sodium uranyl oxonium silicate as main phase (>95%).This finding could be useful for the long term predictive modelling of groundwater chemistries in contact with a high-level nuclear waste repository [9].