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74.29mg·g-1.动力学研究表明其吸附速率快,在1h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.
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^（-l）, 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 pseudo- second-order kinetic model. The thermodynamic parameters △G^0, △H^0, and △S^0 were also calculated. The negative AGO 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.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2012年第7期1615-1622,共8页
Acta Physico-Chimica Sinica
基金
国家自然科学基金(21073126)
四川省自贡市科学技术局重点基金(10X01)资助项目~~
关键词
壳聚糖
Β-环糊精
吸附
氯酚
热力学
动力学
Chitosan
β-Cyclodextrin
Adsorption
Chlorophenols
Thermodynamics
Kinetics
