科研之友
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摘要
Radioactive strontium (Sr-90) is one of the major contaminants in low-level radioactive wastewaters from nuclear power plants. Antimony silicate is regarded as a selective inorganic adsorbent for Sr-90 removal. In this paper, a safe method was developed to prepare antimony silicate adsorbents. In the synthetic process, stable and low-toxic antimony trichloride (SbCl3) was used as an antirhony source instead of volatile antimony pentachloride (SbCl5). Besides an Sb-rich phase with well-crystalized pyrochlore structure, an Si-rich phase with amorphous structure can be detected, which may facilitate strontium adsorption due to its large specific surface area. The batch experiments demonstrate that the synthesized material can offer a favorable adsorption of Sr(II) over a broad pH range of 1.2-11 and a wide concentration range of co-existing ions, The highest K-d value amounts to nearly 10(8) mL/g at an Si/Sb ratio of 2.9. Calcium ions have a significant negative influence on strontium adsorption. The Kd value drops to 102 mL/g at a Ca2+ concentration of 0.1 M. The kinetic performance of Sr(II) adsorption onto antimony silicate follows the pseudo-second-order model and the adsorption isotherms coincide well with the Freundlich model. Moreover, the thermodynamic study reveals that the adsorption is an endothermic and spontaneous process.
- 出版日期2015-10-1
- 单位清华大学
