| 内容提要: |
Radioactive strontium is one of the main hazardous fission products present in radioactive wastewater, and poses a great threat to human and environment. It is critical and urgent for developing new techniques and materials for rapid and effective removal of radioactive Sr2+ from aqueous solutions. Herein, we synthesized 2D K/Zn/Sn/S metal sulfide (KZTS) nanosheets by a simple one-step hydrothermal method for Sr2+ removal. SEM and EDS showed that KZTS nanosheets possessed layer-stacked nanosheet-like morphology with the formula of K6.13Zn4Sn5S17.06. Structural analyses based on XRD, Raman and XPS data confirmed the exchangeable K+ ions between the anion Zn−S−Sn layers and the soft S2− ligands on the structures, which were very favorable for Sr2+ adsorption. The adsorption ability of KZTS nanosheets for Sr2+ was evaluated in detail by batch experiments. KZTS nanosheets showed the ultrafast adsorption of Sr2+ with the equilibrium time of 1 min. The maximum adsorption capacity, calculated by Langmuir isotherm, was as high as ~ 55 mg/g. Effective adsorption (Kd > 10e4 mL/g) was observed in a wide pH range of 2−13, which was rare in literatures. Moreover, KZTS nanosheets exhibited higher selectivity for Sr2+ in large excess of Na+ and K+ than in high Ca2+ and Mg2+ concentration solutions. The adsorption mechanism was determined by macroscopic and microscopic studies as ion exchange between K+ ions and Sr2+ ions. Finally, negligible toxic ions leached from 2D KZTSs indicated the environmentally friendly nature of 2D KZTSs. Our work suggests that KZTSs could be desirable adsorbents for radioactive wastewater treatment, especially in an emergency case such as in a nuclear power plant accident. |