有机修饰塿土对苯酚的吸附及其热力学特征

研究了用十六烷基三甲基溴化铵（CTMAB）单一修饰和十六烷基三甲基溴化铵＋十二烷基磺酸钠（CTMAB＋SDS）混合修饰填土耕层、粘化层后土样对苯酚的吸附及其热力学特征，并对其吸附机理进行探讨．结果表明，填土两层次土样表面修饰后均能显著增强对苯酚的吸附能力，耕层土样对苯酚吸附呈现100GCB（100％CTMAB修饰耕层土样）〉120GCS（100％CTMAB＋20％SDS修饰耕层土样）〉50GCB（50％CTMAB修饰耕层土样）〉GCK（耕层原土）的趋势，粘化层土样相应地呈现100NCB（100％CTMAB修饰粘化层土样）〉50NCB（50％CTMAB修饰粘化层土样）〉120NCS（100％CTMAB＋20％SDS修饰粘化层土样）〉NCK（粘化层原土）的变化趋势；耕层原土吸附苯酚能力高于粘化层原土，但修饰后粘化层土样对苯酚的吸附能力超过耕层；两层次原土对苯酚的吸附呈现增温效应，但修饰后耕层土样转变为随温度上升吸附量下降的增温负效应特征，而粘化层修饰土样呈现增温效应特征，证实耕层修饰土样对苯酚以物理吸附为主，而粘化层修饰土样以化学吸附为主；Henry模型可用于描述苯酚在供试土样中的吸附；供试土样对苯酚的吸附属自发性反应，耕层修饰土样的吸附属焙减、熵减过程，自发性取决于焙减，而粘化层的吸附属焓增、熵增过程，自发性主要取决于熵增．

Effects of modification of manural loessial soil by adding organic compounds on phenol adsorption and its thermodynamic characteristics

Two soil layers, cultivated layer (CL) and claying horizon (CH), sampled from a manural loessial soil or lou soil, were modified by addition of cetyltrimethylammonium bromide alone (CTMAB) at different rates and the mixture of cetyltrimethylammonium bromide and sodium dodecylsulphonate (CTMAB+SDS), the effects of the modified layers on the adsorption and thermodynamic characteristics of phenol were studied, and the adsorption mechanisms were investigated at the same time. Results showed that the adsorption ability of both layers was increased significantly after such modifications in terms of amount of phenol adsorbed. The adsorption amount for the cultivated layer showed such a trend as 100GCB (100%CTMAB modified CL) > 120GCS (100%CTMAB+20%SDS modified CL) > 50GCB (50%CTMAB modified CL) > GCK (unmodified CL), while that of the claying horizon as the followings: 100NCB (100%CTMAB modified CH) > 50NCB (50%CTMAB modified CH) > 120NCS (100%CTMAB+20%SDS modified CH) > NCK (unmodified CH). For the unmodified soil, the adsorption ability of the claying horizon was lower than that of the cultivated layer. However, by modification, the adsorption ability of the claying horizon was higher than that of the cultivated layer. The adsorption ability of the two original layers was increased with the rise of temperature, having a positive temperature effect, while that of the modified cultivated layer was decreased with the rise of temperature, having a negative temperature effect. In contrast, the modified claying horizon showed a positive temperature effect. All this reveals that the adsorption of the modified cultivated layer was determined by physical adsorption whereas the modified claying horizon by chemical adsorption. Henry equation was used to describe the phenol adsorption isotherm, and the thermodynamic parameters showed that the phenol adsorption for the modified soil was spontaneous. The adsorption of the cultivated layer was a process of both enthalpy decrease and entropy decrease process, its spontaneity being controlled by enthalpy decrease while that of the claying horizon is a process of both enthalpy increase and entropy increase process, its spontaneity being controlled by entropy increment.