蜂窝状离子印迹壳聚糖/ZSM-5复合泡沫对U(Ⅵ)的吸附特性

Adsorption Properties of Honeycomb-Like Ion-Imprinted Chitosan/ZSM-5 Composite Foams for U(Ⅵ) Ions

工业含铀废水排放导致的放射性污染严重危害环境安全和人体健康。文中制备了蜂窝状离子印迹壳聚糖/ZSM-5(ICZ)复合泡沫,用于选择性吸附U(Ⅵ)。结果表明,不同原料配比制备的ICZ泡沫中,ICZ-2对U(Ⅵ)吸附效果最佳,是由于其兼具发达的蜂窝状结构和丰富的功能基团。与非离子印迹吸附剂比较,离子印迹吸附剂ICZ-2能选择性识别目标离子,因此具有更高的吸附容量和选择性。吸附等温线符合Langmuir模型,表明为均相单分子层吸附,吸附容量达280.09 mg/g;吸附动力学符合拟二级模型,表明化学吸附是控速步骤。ICZ-2对U(Ⅵ)的吸附以功能基配位络合为主要机理。ICZ-2吸附容量高、吸附速率快、吸附选择性好,有望用于含铀废水处理。

The radioactive pollution of uranium-containing effluent seriously harms environmental safety and human health. Herein, the honeycomb-like ion-imprinted chitosan/ZSM-5(ICZ) composite foams were prepared and used for the selective sorption of U(Ⅵ). The results suggest that ICZ-2 is the best among various ICZ foams with different raw material ratios, owing to its well-developed honeycomb-like structure as well as the presence of abundant functional groups. Compared to the non-imprinted sorbent, the ion-imprinted sorbent ICZ-2 presents higher sorption and better selectivity since it could smartly recognize the target ions. The sorption isotherms could be described by Langmuir model, suggesting homogeneous monolayer sorption with the maximum sorption capacity of 280.09 mg/g. The sorption kinetics could be fitted by the pseudo-second order model, indicating chemisorption as the rate-controlling step. The main sorption mechanism is related to U(Ⅵ) coordination by the functional groups of ICZ-2. The ICZ-2 presents a high sorption capacity, fast kinetic rate, and good selectivity for U(Ⅵ), therefore it has potential applications for the treatment of U(Ⅵ) –containing wastewater.