Résumé
In this work, crystalline silicotitanates (CST) nanomaterials of sitinakite, Na2Ti2O3SiO4•2H2O, which can be used for Sr2+ removal from aqueous media, were synthesized and characterized. XRD analyses demonstrated that with the increase of the Ti/Si ratio in the starting gel, an increase of the crystallinity was observed, up to a point where sodium nonatitanate (Na4Ti9O20) formation was observed. N2 adsorption/desorption analyses displayed specific surface areas ranging between 56 m2.g-1 and 290 m2.g-1. Extraction kinetics experiments showed that above an estimated value ranging between 50 and 100 m2.g-1, the specific surface area does not influence the sorption rate of the CST anymore. The main conclusions from the sorption experiments are that, without Ca2+, both CST and nonatitanate present high sorption capacities of about 200 mg.g-1. When Ca2+ is added, a drastic drop of the sorption capacities was observed for the nonatitanate, which was also observed for all the CST in a much less pronounced way. Hence, by varying the Ti/Si ratio in the precursor gel, it is possible to tailor the CST’s properties. Furthermore, the CST showed a high affinity towards Sr2+, even when a competitor cation (Ca2+) was added in excess, which makes it a promising candidate for 90Sr decontamination.