中文摘要：

研究了以十六烷基三甲基溴化铵（CTMAB）单一修饰和CTMAB＋十二烷基磺酸钠（SDS）混合修饰的塿土耕层和黏化层土样对CrO4^2-的吸附热力学特征及机理、结果表明，Langmuir模型是描述两层次修饰土对CrO4^2-吸附等温线的最佳模型，供试土样吸附亲和力（b^L）和最大吸附量（qm^L）大小具有相同的变化趋势，同时与实验结果具有较好的一致性；热力学研究结果表明，修饰后塿土两土层各土样吸附CrO4^2-的表观吸附自由能变（△G）均为负值，属自发性反应，同一层次土壤中，各修饰土样。△G基本上呈现100CB〉120CS〉50CB的顺序，表明-△G、b^L与qm^L、平衡吸附量的同序性、机理研究证实，塿土两层次土样对CrO4^2-的吸附是一个物理吸附和化学吸附共存的吸附机制，土壤表面的有机修饰具有增强物理吸附而减弱化学吸附的作用。

英文摘要：

The thermodynamic characteristics and mechanism of CrO4^2- adsorption on soil samples gathered tom the tillage layer （TLLS） and clay layer （CLLS） of lou soil modified singlely with cetyltrimethylammonium bromide （CTMAB） and modified mixedly with cetyltrimethylammonium bromide ＋ sodium dodecylsulphonate （CTMAB＋SDS） were studied. Langmuir model was the best one in describing CrO4^2- adsorption isotherms on two layer modified soils; in the test samples, the size of adsorption affinity （b^L） possessed same variation tendency with maximum adsorption amount （qm^L）, and was same relatively with the test results. The results of study of thermodynamics showed that the apparent adsorption free energy change（△G） of each modified soil sample adsorpted CrO4^2- was all negative value, belonging to spontaneous reaction. In the same layer soil, each modified soil sample -△G appeared basically the size order of 100CB〉120CS〉50CB, which showed the same sequence among -△G, b^L ,qm^L and equilibrium adsorption amount. The studies on the mechanism confirmed that the CrO4^2- adsorption of two layer lou soil was a physical and chemical coexist adsorption mechanism; organic modification of soil surface possessed the action of strengthening the physical adsorption but weakening the chemical adsorption.