阴离子β-环糊精/Fe3O4磁性微球对Cu2+的吸附

通过对b-环糊精（b-CD）改性制备了阴离子b-环糊精/Fe₃O₄磁性微球（b-CDM），并研究了b-CDM对Cu²⁺吸附的热力学、动力学及循环使用性能，借助数学拟合的方法得到了吸附热力学和动力学参数，探讨其吸附机理。研究表明，b-CDM对Cu²⁺的吸附是一个自发的放热过程，Langmuir与Freundlich等温吸附模型均适用于b-CDM对Cu²⁺的吸附研究，b-CDM对Cu²⁺的吸附经历颗粒外部扩散-孔隙扩散-吸附反应3个阶段，该吸附过程既存在物理吸附，又有化学吸附，在吸附温度298、308、318 K下得到的吸附速率常数分别为0.0906、0.1161、0.1674 g·mmol^-1·min^-1，吸附表观活化能为24.12 kJ·mol^-1，且随着介质中Cu²⁺平衡吸附量的增大，b-CDM对Cu²⁺的吸附驱动力由焓变转变为熵变。b-CDM重复利用8次后，对Cu²⁺的除去率由首次使用时的95.20%下降至88.21%。

Adsorption of Cu2+ by anionic β-cyclodextrin/Fe3O4 magnetic microspheres

Anionic b-CD/Fe₃O₄ magnetic microspheres (b-CDM) were prepared by modified b-cyclodextrin. The adsorption thermodynamics, kinetics and recycle about the adsorption of Cu²⁺ by b-CDM were studied. With a mathematical fitting method, adsorption thermodynamic and kinetic parameters were obtained, and adsorption mechanism was discussed. Thermodynamic studies show that the adsorption of Cu²⁺ by b-CDM is spontaneous and it is an exothermic process. Further study indicates that it is appropriate to use Langmuir and Freundlich isothermal adsorption models to study the adsorption process. Kinetic study shows that the adsorption of Cu²⁺ by b-CDM is a process consisting of three stages, which are external diffusion, pore diffusion and adsorption reaction. Both physical adsorption and chemical adsorption take place. The value of apparent adsorption activation energy is 24.12 kJ·mol^-1. At adsorption temperature of 298 K, 308 K, and 318 K, the adsorption rate constants are 0.0906, 0.1161, 0.1674 g·mmol^-1·min^-1, respectively. As the equilibrium absorption capacity of Cu²⁺ increases, the driving force of adsorption varies from enthalpy change to entropy change. After b-CDM was reused for 8 times, the removal rate declined from 95.20% to 88.21%.