| 内容提要: |
A novel metal sulfide (KZTS) adsorbent has been synthesized using a simple one-step hydrothermal method for radioactive Sr2+ removal from aqueous solutions. XRD and TG analyses indicated that KZTS was chemically and thermally stable. SEM-EDS and TEM images showed that KZTS possessed both layered and polyhedral morphologies with the formula of K1.67Zn0.67Sn2.17S6.00 and K5.84Zn3.47Sn5.04S16.99, respectively. The average formula was determined to be K1.87ZnSn1.68S5.30 using ICP-OES. The adsorption ability of KZTS for Sr2+ was evaluated in detail by batch experiments. The kinetics studies showed that Sr2+ was rapidly removed from the aqueous solution within the equilibrium time of 10 min. According to Langmuir isotherm, the maximum adsorption capacity of KZTS was 19.3 mg/g at 298 K and the high value of the Langmuir constant indicated the high affinity of KZTS for Sr2+. The adsorption mechanisms involved ion exchange and surface Sr–S bonding interactions, with the former dominating. High adsorption performance was observed over a broad pH range of 3–11, although it could be inhibited by co-existing ions, especially Ca2+ and Mg2+. The adsorbent showed a high distribution coefficient (Kd = 1.26×106 mL/g) and negligible adsorbate leaching at low Sr2+ concentrations, indicating the strong and irreversible adsorption of Sr2+ on KZTS. Further, KZTS exhibited high selectivity for Sr2+ in alkaline and tap water. These remarkable features suggest that KZTS is a highly desirable adsorbent to remove radioactive strontium from radioactive wastewater. |