PAMAM接枝稻草对Nd3+、Sm3+、La3+的吸附特性

Adsorption behavior of Nd3+、Sm3+、La3+ on rice straw functionalized with PAMAM

摘要:

以环氧氯丙烷为交联剂，将聚酰胺胺树状大分子(PAMAM)接枝到稻草基体上，利用FTIR、SEM、XRD、TG等对其结构进行了表征和分析。考察了其对Nd3+、Sm3+、La3+ 3种稀土金属离子的吸附性能，探讨了吸附时间、稀土金属离子浓度、吸附温度、溶液pH等因素对吸附性能的影响。同时对吸附过程的动力学、吸附等温线和吸附热力学进行了研究。结果表明：所制备的吸附剂对Nd3+、Sm3+、La3+ 3种稀土金属离子的吸附平衡时间约为4 h，平衡吸附量分别为47.14、40.11和50.12 mg/g。吸附过程符合拟二级动力学模型和Freundlich等温线，表明此吸附过程是属于化学吸附过程。吸附热力学研究表明，此吸附过程是自发进行的，同时吸附过程是一个混乱度增加的熵增过程。

Abstract:

The functionalized rice straw with polyamidoamine(PAMAM) was prepared with epichlorohydrin as crosslinking agent, and its structure was characterized and analyzed by FTIR, SEM, XRD and TG. The adsorption properties of the functionalized rice straw for Nd3+, Sm3+and La3+ were researched. Physicochemical factors such as adsorption time, initial rare earth metal ions concentration, adsorption temperature, and pH affecting magnitude of rare earth metal ions adsorption were researched. At the same time, the kinetics behavior, adsorption isotherm, and thermodynamics parameters of the adsorption process were further investigated. The results showed that the adsorption equilibrium time was about 4 h for Nd3+, Sm3+ and La3+. And adsorption capacity of Nd3+, Sm3+and La3+ were 47.14, 40.11 and 50.12 mg/g, respectively. At the same time, the adsorption process fit the pseudo-second-order kinetic model and Freundlich isotherm, which indicate that the adsorption process is chemical adsorption process. In additional, thermodynamic data of the adsorption process shows that the adsorption process is spontaneous. And the randomness is increased at the solid-solution interface during adsorption process.