Mg/Al水滑石的焙烧产物吸附酸性红88的动力学和热力学机理研究  

Kinetics and Thermodynamics for Acid Red 88 Adsorption on Calcined Layered Double Hydroxides

作　　者：倪哲明[1] 王巧巧[1] 姚萍[1] 刘晓明[1] 李远[1] 

机构地区：[1]浙江工业大学化学工程与材料学院先进催化材料实验室,杭州310032

出　　处：《化学学报》2011年第5期529-535,共7页Acta Chimica Sinica

基　　金：浙江省自然科学基金(No.Y406069)资助项目

摘　　要：文章研究了Mg/Al水滑石焙烧产物(LDO)对酸性红88(AR88)的吸附性能及其机理.考察了温度对其吸附性能的影响,探讨了吸附过程的动力学和热力学规律.热力学研究表明:LDO对AR88的吸附过程稍符合Langmuir等温吸附.从Langmuir等温式计算的ΔH,ΔS为负值,表明吸附过程为放热、熵减小的过程,这是因为LDO在吸附酸性染料后恢复了层状结构;不同温度下ΔG均为负值,表明吸附过程是自发进行的.动力学研究表明:吸附动力学符合准二级动力学模型,动力学计算吸附过程的活化能Ea=54.53 kJ·mol-1.利用Materials Studio 4.3软件中的CASTEP程序模块和Focite模块模拟了AR88染料分子在Mg/Al水滑石(LDHs)的尺寸大小和排列方式,推测吸附机理是以表面吸附占主要优势并伴有少部分插层.The adsorption thermodynamics and mechanism of acid red 88 （AR88） in aqueous solution ad sorbed by LDO were investigated. The adsorption isotherms were measured at different temperatures, and the thermodynamic functions were also calculated. The results indicate that the equilibrium isotherms of uptake of AR88 by LDO were well fitted to the Langmuir equation, and thermodynamic parameters such as AGФ, △HФ and △SФ were calculated from Langmuir constants. The negative values confirm the spontaneous and exothermic nature of the adsorption process. Three kinetics models were used to fit the kinetics experimental data, and it was found that the pseudo-second order kinetics model could be used to describe the uptake process appropriately. The value of Ea was calculated to be 54.53 kJ.mol^-1. The size and arrangement of AR88 molecular on LDHs were simulated using the CASTEP and Focite program, and speculation on mechanisms was that adsorption of AR88 on LDHs surface accompanied with a little AR88 intercalated into the layer.

关 键 词：Mg/Al水滑石 酸性红88 动力学 热力学 

分 类 号：O643.1[理学—物理化学]