CeO2/NaF吸附剂的制备及其对MoF6的吸附性能研究

Preparation of adsorbent CeO_2/NaF and its adsorption performance for MoF_6

将作为粘结剂和造孔剂的高分子羧甲基纤维素钠(Carboxymethylcellulose,CMC)、Ce F3和Na F按4:9:62的质量比例混合,再加一定量的水(CMC与水的比为1:6),通过混捏、成形和烧结等程序制得了一种新型的Ce O2/Na F吸附剂颗粒。通过研究Ce O2的掺杂对Na F吸附剂表观性质和吸附性能的影响发现:Ce O2/Na F吸附剂的比表面积为(0.84±0.04)m2·g-1,是相同条件下制得的Na F吸附剂的两倍以上;孔隙率为42.2%,也优于Na F吸附剂;Ce O2/Na F和Na F吸附剂对Mo F6的饱和吸附容量相当,但Ce O2/Na F吸附剂的初始吸附速率明显大于Na F吸附剂;吸附于Ce O2/Na F吸附剂上的Mo F6在150–300°C单个温度段解吸附,而吸附于Na F吸附剂上的Mo F6在100–300°C和350–400°C两个温度段发生解吸,表明Ce O2的引入在一定程度上起到了稳定Mo F6的作用。在Na F吸附剂内掺杂Ce O2可以改变Na F吸附剂部分表观性质,从而改善Na F的吸附性能。

Background： The fluoride volatility process has been developed to recover uranium from spent nuclear fuel. And the fluoride adsorption technique is usually applied in the purification and collection of UF6 during the fluoride volatility process. Purpose： This study aims to investigate the characteristics and sorption performance of a novel sorbent CeO2/NaF synthesized by doping NaF with CeF3. Methods： With polymer sodium carboxymethyl cellulose （CMC） as a binder and pore-forming agent, CeF3 and NaF was mixed according to a mass ratio of 4：9：62, and then water were added （the ratio of CMC to water is 1：6）. The porous CeO2/NaF adsorbent particles were prepared by a mixing, molding and sintering process. The characteristics and adsorption performance of the adsorbent particles were analyzed and characterized. Results： Specific surface area of CeO2/NaF was （0.84±0.04）m2·g-1, which was twice of NaF sorbent made under the same process. Porosity was 42.2%, which was larger than that of NaF sorbent. The initial adsorption rate of MoF6 on CeO2/NaF was much higher than that of NaF sorbent. The temperature zone for desorption of MoF6 from CeO2/NaF ranged from 150°C to 300°C, while there were two desorption zones for desorption of MoF6 from NaF sorbent, which varied from 100°C to 300°C and 350°C to 400°C, respectively. This phenomenon showed that CeO2 might stabilize Mo6＋ in MoF6. Conclusion： The physical properties of NaF could be changed by doping with CeO2, and its adsorption performance was also improved.