298K毛吸附溴化烷基三甲铵的性质及自由能

用液 /固吸附计量置换模型 ( SDM- A) ,研究了 2 98K羊毛纤维吸附溴化烷基三甲铵阳离子表面活性剂 CTAB和 DTAB的吸附等温线 ,结果表明它们均遵从 SDM- A的线性作图关系 .用 SDM-A的线性参数βα 和 q/z很好地描述了碳氢链长及加盐效应对于吸附性质的影响规律 ,特别是能定量地描述加盐效应对于吸附同时具有的促进和抵消两种相反作用的程度 ,并用 SDM- A的热力学 ,由线性参数计算得到了不同体系的吸附亲和能 ΔGA,解吸能 ΔGD 及总过程的自由能 ΔGP.一个吸附体系中 ,ΔGA 为常数且为较大的负值 ;ΔGD 为随溶液体相浓度 c增大而增大的正值 ;ΔGP为与 lgc呈线性关系的较小的负值 .计算所得结果能很好地解释实验事实 ,并可从更深层次上揭示吸附机理 .

Performance and Free Energy of Wool Adsorbing Alkyltrimethylammonium Bromide at 298K

Based on the Stoichiometric Displacement Model of Adsorption (SDM-A) in liquid/solid system, the adsorption isotherms of hexadecyl-trimethylammonium bromide (CTAB) and dodecyl-trimethylammonium bromide (DATB) adsorbed by wool fiber at 298K are studied. It is shown that all the adsorption systems follow the illustratively linear relationships of the SDM-A. The linear adsorption parameters,β α and q/z , of SDM-A can describe well the effecting rules of C-H chain length and salt addition on adsorption performance, particularly, they can quantitatively describe the extents of two opposite actions of strengthening and counteraction which salt addition affects simultaneously on the adsorption. And, with these parameters, the Gibbs free energies for adsorption affinity (△ G A), desorption(△ G D) and whole displacement adsorption process(△ G P) are calculated according to the thermodynamics of SDM-A. In a given adsorption system, △ G A is a constant and a greater value with negative sign, while △ G D are less positive values increasing with concentrations of bulk solution c , and △ G P are less values with negative sign, which is of linear relationship to lg c . The results calculated can explain well the experimental facts and can deeply explore the specific adsorption mechanism.