阴离子型有机化合物在LDHs上的动力学和热力学研究

本文考察水滑石焙烧产物MgAl-LDO吸附3种阴离子染料AcidRed88（AR88）、AcidOrange 3（AO3）、AcidViolet90（AV90）过程中的热力学和动力学机理，并在不同温度下探究该吸附过程的热力学参数。实验结果表明：MgAl-LDO对染料阴离子的吸附过程复合Langmuir吸附等温模型，且为自发、放热的过程。3种染料在MgAl-LDO上的吸附过程均符合准二级反应动力学模型，且该吸附过程是由MgAl-LDO与阴离子染料之间的反应速率控制而不是两者之间的扩散作用。计算所得的吉布斯自由能绝对值在7~15kJ·mol^-1，这主要是由染料阴离子与MgAl-LDHs层板的氢键作用产生，结合MaterialsStudio 5.5软件模拟染料分子在MgAl-LDHs上的排列分布，推测MgAl-LDO对阴离子染料的吸附机理是表面吸附（占优势）与层间插层的协同作用。

Kinetics and Thermodynamics for Anionic Dye Adsorption on Calcined Layered Double Hydroxides

The adsorption thermodynamics and mechanism of acid red 88(AR88), acid orange 3(AO3) and acid violet 90(AV90) on MgAl Layered double hydroxides with 3:1 Mg/Al molar ratio were investigated. The adsorption isotherms were measured at different temperatures, and the functions of thermodynamics were also calculated. The results indicated that the adsorption process on MgAl-LDO were well consistent with the Langmuir equation and were also spontaneous and exothermic. Three kinetics models were used to describe the kinetics experimental data, and it was found that the pseudo-second order kinetics model was best fitted. The Gibbs free energy was calculated to be 7 to 15 kJ·mol^-1 because of Hydrogen bonds between the layers and dye molecular. According to the calculation of Materials Studio 5.5, the mechanism of adsorption process was that most dye anions were adsorbed on the surface of MgAl-LDO accompanied with intercalated into the layer.