Laponites(®) for the Recovery of (133)Cs, (59)Co, and (88)Sr from Aqueous Solutions and Subsequent Storage: Impact of Grafted Silane Loads

In this study, silylated Laponites(®) (LAP) were synthetized with various loads of 3-aminopropyltriethoxysilane (APTES) to evaluate their adsorption properties of (133)Cs, (59)Co, and (88)Sr during single-solute and competitive experiments. The increase in the initial load of APTES increased the adsorbed amount of APTES in the resulted grafted clay. The characterization of LAP-APTES exhibited a covalent binding between APTES and LAP and emphasized the adsorption sites of APTES for each tested load. In comparison with raw LAP, LAP-APTES displayed significantly higher adsorption properties of Co(2+), Cs(+), and Sr(2+). The competitive adsorption of these three contaminants provides a deeper understanding of the affinity between adsorbate and adsorbent. Therefore, Co(2+) displayed a strong and specific adsorption onto LAP-APTES. Except for Cs(+), the adsorption capacity was improved with increasing the load of APTES. Finally, the desorption behavior of the three contaminants was tested in saline solutions. Cs(+) and Sr(2+) were significantly released especially by inorganic cations displaying the same valence. Conversely, desorption of Co(2+) was very low whatever the saline solution. LAP-APTES, therefore, presented suitable adsorption properties for the removal of radionuclides especially for Co(2+), making this material suitable to improve the decontamination of radioactive wastewaters.