三聚磷酸钠交联磁性壳聚糖树脂对铀酰离子的吸附特性

以三聚磷酸钠为交联剂,分别在pH值为3和8条件下制备具有不同交联度的磁性壳聚糖树脂(TPP-MCR)。考察了pH值、吸附时间及初始铀浓度对TPP-MCR吸附UO2+2的影响。结果表明,pH值对两种不同交联度TPP-MCR吸附UO2+2的影响差别较大。FTIR分析表明,TPP-MCR中磷酸根为UO2+2主要吸附位。TPP-MCR吸附UO2+2为吸热自发过程,吸附动力学可用拟二级动力学模型拟合,表明以化学吸附为主。吸附等温线可用Langmuir模型拟合,293K时最大吸附容量为166.7mg/g。吸附UO2+2后的TPP-MCR可用0.1mol/L HNO3-0.1 mol/L EDTA溶液洗脱再生,并可重复使用多次。

Adsorption ofUO2+2 Ion onto Tripolyphosphate-crosslinked Magnetic Chitosan Resin

The tripolyphosphate-crosslinked magnetic chitosan resins (TPP-MCR) were prepared at pH＝3, 8 for obtaining resins with different cross-linking degrees. The effects of the pH, the adsorption time and the initial uranium concentration on UO²⁺₂ adsorption onto the TPP-MCR were investigated. The results show that the effects of pH on UO²⁺₂ adsorption differ significantly with the cross-linking degree of the TPP-MCR. The analysis of FTIR indicates that the phosphate groups of the TPP-MCR are the main active sites for UO²⁺₂ adsorption. The adsorption of UO²⁺₂ onto TPP-MCR is endothermic and spontaneous in nature. The adsorption kinetics follows the pseudo second order equation, evidencing chemical adsorption as the rate-limiting step. The adsorption equilibrium data can be described by Langmuir isotherms with the maximum adsorption capacity of 166.7 mg/g at 293 K. The TPP-MCR loaded with UO²⁺₂ can be desorbed by 0.1 mol/L HNO₃ 0.1 mol/L EDTA and reused for several cycles.