阴离子β-环糊精/Fe3O4磁性微球对Cu2＋的吸附  

Adsorption of Cu^(2+) by anionic β-cyclodextrin/Fe_3O_4 magnetic microspheres

作　　者：李凯斌[1] 沈一丁[1] 费贵强 李仲谨[1] 

机构地区：[1]陕西科技大学化学与化工学院 教育部轻化工助剂化学与技术重点实验室,陕西西安710021

出　　处：《化工学报》2014年第6期2148-2155,共8页CIESC Journal

基　　金：国家自然科学基金项目(50573046);陕西省科技计划自然基金项目(2012JM2016);陕西科技大学研究生创新工程种子项目(2013014);陕西科技大学研究生创新基金项目~~

摘　　要：通过对β-环糊精(β-CD)改性制备了阴离子β-环糊精/Fe3O4磁性微球(β-CDM),并研究了β-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,β-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β-CDM对Cu2+的吸附研究,β-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、0.1674g·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,β-CDM对Cu2+的吸附驱动力由焓变转变为熵变。β-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%。Anionic β-CD/Fe304 magnetic microspheres （β -CDM） were prepared by modified β -cyclodextrin. The adsorption thermodynamics, kinetics and recycle about the adsorption of Cu2＋ by β-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 β-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 β-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 β-CDM was reused for 8 times, the removal rate declined from 95.20% to 88.21%.

关 键 词：Β-环糊精 磁性微球 吸附 动力学 热力学 

分 类 号：X703[环境科学与工程—环境工程] O647.3[理学—物理化学]