硅基HDEHP吸附剂对硝酸体系中Zr(Ⅳ)的吸附

以多孔二氧化硅聚合物颗粒为载体,采用真空灌注法合成了一种复合型硅基吸附剂HDEHP/SiO_2-P(二(2-乙基己基)磷酸酯,di-2-ethylhexylphosphoric acid,HDEHP),用于吸附硝酸体系中的Zr(Ⅳ)。通过扫描电子显微镜(SEM)、差热-热重分析(TG-DTA)等手段对吸附剂进行了表征。研究了硝酸体系下,吸附剂对Zr(Ⅳ)的吸附选择性以及时间、温度对吸附性能的影响。结果表明:该吸附剂在一定酸度范围内对Zr(Ⅳ)有良好的吸附选择性;吸附动力学符合准二级动力学模型,吸附平衡时间为15h;吸附等温线符合Langmuir吸附等温线模型;该吸附剂对Zr(Ⅳ)的吸附容量随温度升高而提高,298K时的吸附容量为0.456 mmol/g。HDEHP/SiO_2-P在吸附Zr(Ⅳ)后,用草酸溶液可以有效地将Zr(Ⅳ)解吸下来,解吸率达到98%,解吸的平衡时间在1h以内。

Adsorption Characteristics of Zr(Ⅳ) From Nitric Acid Solution Using a Silica-Based Macroporous HDEHP Adsorbent

A silica-based HDEHP/SiO₂-P adsorbent was synthesized to adsorb Zr(Ⅳ) from nitric acid solution. The adsorption behavior of Zr(Ⅳ) from nitric acid solution containing some typical fission products (FPs) was studied. The adsorbent exhibited much higher affinity for Zr(Ⅳ) over other FPs within a wide HNO₃ concentration range. Also, the obtained results indicate that the Zr(Ⅳ) adsorption capacity reaches to 0.456 mmol/g at 298 K. The adsorption kinetics and isotherm are well described by the pseudo-second-order model and the Langmuir equation, respectively. Adsorbed Zr(Ⅳ) onto HDEHP/SiO₂-P can be effectively eluted by H₂C₂O₄ solution in equilibrium time of about 1 h, and the desorption ratio reaches 98%.