改性硅藻土负载磷钼酸铵复合吸附剂的制备及其吸附Cs^(+)研究

Study on preparation of modified diatomite loaded ammonium phosphomolybdate composite adsorbent and its adsorption performance of Cs^(+)

盐湖卤水中存在与铯离子性质相近的高浓度碱金属元素,使盐湖卤水中铯资源的选择性分离变得十分困难。基于此,以价廉易得的硅藻土为基体、氯化铝为铝源,采用水热法对硅藻土表面进行改性,然后将经过500℃煅烧后的改性硅藻土作为载体材料,通过浸渍法将磷钼酸铵负载到载体材料表面制备复合吸附剂。采用X射线衍射仪、扫描电子显微镜、傅里叶变换红外光谱仪对所制备材料进行表征,并开展了Cs^(+)吸附、脱附性能的系统研究。结果表明:所制备吸附剂在复杂体系中保持了较高的选择性,吸附量可达79.41 mg/g;对吸附数据进行动力学和吸附等温模型拟合,发现吸附过程更符合准二级动力学模型和Langmuir吸附等温模型;以3 mol/L NH_(4)NO_(3)为脱附剂时其脱附率高达88.23%,经过4次吸附-脱附循环实验后,吸附量仍保持在初始吸附量的74.38%。

There are high concentrations of alkali metal elements in salt lake brine with similar properties to cesium ions,which makes the selective separation of cesium resources in salt lake brine very difficult.In this study,the surface of diato-mite was modified by hydrothermal method with cheap and easily available diatomite as the matrix and aluminum chloride as the aluminum source.The prepared modified diatomite was calcined at 500℃ as the carrier material,and ammonium phosphomolybdate was loaded onto the surface of the carrier material by impregnation to prepare composite adsorbent.The prepared materials were characterized by X-ray diffraction,scanning electron microscopy and Fourier transform infrared spectroscopy.The adsorption and desorption properties of Cs^(+)were studied systematically.The results showed that the pre-pared adsorbent maintained high selectivity in the complex system,and the adsorption capacity reached 79.41 mg/g.The ad-sorption data were fitted by kinetic and adsorption isotherm models.The results showed that the adsorption process was more in line with the quasi-second-order kinetic model and Langmuir adsorption isotherm model.When 3 mol/L NH_(4)NO_(3) was used as the desorption agent,the desorption rate was as high as 88.23%.After four adsorption-desorption cycle tests,the ad-sorption amount could remain at 74.38%of the initial adsorption amount.