CTMAB对塿土表面的修饰机制  

Modification Mechanism of CTMAB on Surface of Lou Soil

作　　者：孟昭福[1] 杨亚提[1] 龚宁[1] 李荣华[1] 张增强[1] 张一平[2] 

机构地区：[1]西北农林科技大学a理学院,陕西杨凌712100 [2]西北农林科技大学a资源环境学院,陕西杨凌712100

出　　处：《土壤通报》2008年第5期1002-1006,共5页Chinese Journal of Soil Science

基　　金：国家自然科学基金(40301021);西北农林科技大学青年学术骨干支持计划资助

摘　　要：以平衡吸附法研究了十六烷基三甲基溴化铵(CTMAB)对塿土耕层·粘化层表面的修饰机制,结果表明,CTMAB在两层次土样上吸附等温线20℃时均呈直线型,40℃时均转变为H型等温线形式·在修饰比例0%～100%CEC区间,土壤表面对CTMAB的亲和力随温度的升高均增加,其吸附具有熵增控制自发性反应的热力学特征,两个温度下,土层吸附CTMAB亲和力之比与土层CEC之比相近;在修饰比例100%～200%CEC区间,土壤表面对CTMAB的亲和力随温度的升高均呈现下降的趋势,呈现放热熵减反应特征,20℃时土层吸附CTMAB亲和力之比与土层CEC之比相近,而40℃时则与土层性质无关。CTMAB在两层次土样上解吸等温线均呈直线型。CTMAB对塿土表面的修饰在100%CEC修饰比例前以离子交换为主,100%后以疏水键结合为主,CTMAB在塿土表面易于吸附但难于解吸,解吸的CTMAB主要是以疏水键形式结合在土壤表面上。A study on the modification mechanism of cetyltrimethylammonium bromide （CTMAB） on soil samples collected from tillage layer （TLLS） and clay layer of Lou soil （CLLS） was carried out. The results show that adsorption isotherms of CTMAB on both layers of soil are linear at 20℃, while H type at 40%. In the range of modification ratio 0-100% CEC, the affinity of soil to CTMAB increased with an increased of temperature. Adsorption of CTMAB was the spontaneous reaction with the characteristics of entropy increment and the ratio of affinity of CLLS to that of TLLS was close to the ratio of CEC. On the contrary, in the range of modification ratio 100-200% CEC, the affinity of soil to CTMAB decreased with an increase of temperature, the adsorption of CTMAB was exothermic and entropy decrement reaction and the ratio of affinity of CLLS to that of TLLS was close to the ratio of CEC also at 20%, but was irrelative between affinity and CEC of soil at 40%. The desorption isotherms are the linear type at both temperatures. The modification of CTMAB on surface of Lou soil is ionic exchange mechanism before modification ratio 100%CEC, while the hydrophobic bond appeared after modification ratio 100%CEC. The adsorption of CTMAB on surface of Lou soil was easier than its desorption and the desorbed CTMAB is adsorbed on the surface of soil by hydrophobic bond.

关 键 词：表面修饰 机理 塿土 CTMAB 平衡吸附法 

分 类 号：X53[环境科学与工程—环境工程]