Preparation of layered titanate nanosheets and the application for Cs+ adsorption from wastewater, effluents and a simulated brine

Developing a stable and efficient adsorbent to recover Cs+ from liquid resources or to remove radioactive Cs+ from wastewater is challenging. In this study, the precursor Cs2Ti6O13 (CTO) was synthesized by the solvothermal and solid-phase sintering methods for the first time, then it was acid-modified to synthesize a novel H-type titanium-based material (H-CTO nanosheets). A series of batch adsorption experiments was carried out. The adsorption of Cs+ on H-CTO was evaluated under different experimental conditions, including contact time, temperature, initial Cs+ concentration, pH, and interfering ions. Experiments show that H-CTO exhibits a larger adsorption capacity (329 mg/g) and better cycle performance than the currently reported titanium-based adsorbents. The cesium ions were easily eluted by the 0.2 M HCl solution; the adsorption capacity did not decrease significantly after five cycles. Furthermore, the adsorption behavior of Cs+ on H-CTO can be described by the Langmuir isotherm and pseudo-second-order kinetic models. Characterization using IR and Raman spectroscopic analyses indicates that the adsorption mechanism of Cs+ on H-CTO involves OH bond cleavage and OCs bond formation. Thermodynamic studies showed that low temperatures are favorable for Cs+ adsorption and are spontaneous. Overall, the results suggest that H-CTO nanosheets are promising for the recovery or removal of Cs+ ions from Cs-containing liquid ores or radioactive wastewater.