物理化学学报 >> 2012, Vol. 28 >> Issue (07): 1615-1622.doi: 10.3866/PKU.WHXB201204282

热力学,动力学和结构化学 上一篇    下一篇

β-环糊精修饰的壳聚糖对氯酚吸附的动力学和热力学

周良春1, 孟祥光1, 李建梅1, 胡伟2, 刘波1, 杜娟1   

  1. 1. 四川大学化学学院, 成都 610064;
    2. 四川理工学院化学与制药工程学院, 四川自贡 643000
  • 收稿日期:2012-03-05 修回日期:2012-04-27 发布日期:2012-06-07
  • 通讯作者: 孟祥光 E-mail:mengxgchem@163.com
  • 基金资助:

    国家自然科学基金(21073126)和四川省自贡市科学技术局重点基金(10X01)资助项目

Kinetics and Thermodynamics of Adsorption of Chlorophenols onto β-Cyclodextrin Modified Chitosan

ZHOU Liang-Chun1, MENG Xiang-Guang1, LI Jian-Mei1, HU Wei2, LIU Bo1, DU Juan1   

  1. 1College of Chemistry, Sichuan University, Chengdu 610064, P. R. China;
    2. School of Chemistry and Pharmaceutical Engineering, Sichuan University of Science & Engineering, Zigong 643000, Sichuan Province, P. R. China
  • Received:2012-03-05 Revised:2012-04-27 Published:2012-06-07
  • Contact: MENG Xiang-Guang E-mail:mengxgchem@163.com
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21073126) and Key Project of the Science and Technology Department of Zigong, Sichuan Province, China (10X01).

摘要:

制备了β-环糊精(β-CD)修饰的壳聚糖(CS)—β-环糊精-6-壳聚糖(CS-CD), 并用傅里叶变换红外(FT-IR)光谱仪, 扫描电镜(SEM), X 射线衍射(XRD)仪和比表面分析仪(BET)进行了表征. 详细研究了其对2-氯酚(2-CP)、2,4-二氯酚(DCP)和2,4,6-三氯酚(TCP)的吸附行为和机理. 研究表明其吸附较好地满足Langmuir 和Freundlich 吸附模型, β-环糊精的引入能够较大地提高吸附效率, 2-CP、DCP和TCP在CS-CD上吸附的最大吸附量分别为14.51、50.68和74.29 mg·g-1. 动力学研究表明其吸附速率快, 在1 h内能达到吸附平衡, 并符合假二级动力学模型. 计算出了热力学参数ΔG0、ΔH0和ΔS0的值, ΔG0为负值表明吸附剂对氯酚的吸附是一个自发的过程. 电解质和溶液pH值对吸附的影响说明在吸附过程中主要是氯酚与吸附剂之间形成了氢键, 并进一步讨论了可能的吸附机理. 改性吸附剂易重复利用, 重复使用六次后的质量和吸附效率与初次相比分别保持在90%和82%以上, 然而CS的质量有较大的损失, 吸附效率也明显降低.

关键词: 壳聚糖, β-环糊精, 吸附, 氯酚, 热力学, 动力学

Abstract:

β-Cyclodextrin (β-CD) modified chitosan (CS), β-cyclodextrin-6-chitosan (CS-CD), was prepared and subsequently characterized by Fourier transform-infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis. The CS-CD was used as an adsorbent for the adsorption of 2-chlorophenol (2-CP), 2,4-dichlorophenol (DCP), and 2,4,6-tuichlorophenol (TCP) from aqueous solutions. The Langmuir and Freundlich models were applied to describe the adsorption isotherms of the chlorophenols. The adsorption parameters have also been evaluated. The calculated maximum adsorption capacities for 2-CP, DCP, and TCP on CS-CD were 14.51, 50.68, and 74.29 mg·g-1, respectively, indicating that the introduction of the β-CD moiety greatly increased the adsorption efficiency. Kinetic studies showed that the adsorptions were fast, in that all of the adsorption equilibria were reached within one hour, and that the adsorption processes followed a pseudosecond- order kinetic model. The thermodynamic parameters ΔG0, ΔH0, and ΔS0 were also calculated. The negative ΔG0 values indicated that all of the adsorption processes were spontaneous. A possible adsorption mechanism has been provided and discussed. The effects of electrolytes and pH values on adsorption revealed that hydrogen bonding between the chlorophenols and CS-CD dominated the adsorption process, which was further confirmed by FT-IR analysis. The adsorbent could be regenerated by washing with ethanol. Following six cycles of usage and regeneration, the mass and adsorption efficiency of the CS-CD remained at 90% and 82%, respectively. CS, however, showed greater mass loss and efficiency reduction following regeneration.

Key words: Chitosan, β-Cyclodextrin, Adsorption, Chlorophenols, Thermodynamics, Kinetics

MSC2000: 

  • O647