亚甲基蓝法测试黏性土阳离子交换量的适用性  

Suitability of Methylene Blue Method for Measuring Cation Exchange Capacity of Clayey Soils

作　　者：王文[1] 梁维云 韦昌富[1,2] 颜荣涛[1] 冯晓乔 WANG Wen;LIANG Weiyun;WEI Changfu;YAN Rongtao;FENG Xiaoqiao(Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering,Guilin University of Technology,Guilin 541004,Guangxi,China;State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China)

机构地区：[1]桂林理工大学广西岩土力学与工程重点实验室,广西桂林541004 [2]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,武汉430071

出　　处：《硅酸盐学报》2021年第10期2106-2114,共9页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(11962004);广西自然科学基金项目(No.2019GXNSFAA245025);广西科技基地和人才专项项目(桂科AD20325010)。

摘　　要：阳离子交换量(CEC)是黏性土重要的物理化学指标,可以用来表征黏性土的物理力学性质,而亚甲基蓝吸附法能够快速测定黏性土的CEC。因此,采用亚甲基蓝吸附法(MB法)、氯化铵–氨水交换法(氨法)、氯化钡缓冲液法(钡法)3种方法对几种典型黏性土的阳离子交换量进行了测试与对比,探究MB法的适用性。结果表明:氨法和钡法测试的结果较为一致,而MB法较氨法和钡法而言,在低CEC时测试结果偏低,高CEC时测试结果偏高。通过X射线衍射试验分析亚甲基蓝分子对黏性土的吸附行为,发现当CEC值较低时(小于40mmol/100g),亚甲基蓝分子在表面吸附;当CEC值较高时(大于40 mmol/100 g),亚甲基蓝分子大量被层间吸附。结合X射线衍射结果,利用晶层间距(d_(001))的变化对MB法的测试结果进行了修正。在低CEC时,采用经验关系修正了MB法的测试结果;在高CEC时,采用d_(001)进行了修正,取得了较好的结果。Cation exchange capacity(CEC)is an essential physicochemical index of clayey soil,which can characterize the physicomechanical properties of clayey soil,and methylene blue method can quickly determine the CEC of clayey soil.Therefore,methylene blue method(MB method),ammonium chloride ammonia water exchange method(ammonia method),and barium chloride buffer method(barium method)were used to measure the CEC of several typical clayey soils,to explore the applicability of MB method.The results show that the ammonia method and barium method are consistent,but MB method is different from ammonia method and barium method;The test result is low when the CEC is low,and the test result is high when the CEC is high.The adsorption behavior of methylene blue to clayey soil was analyzed by X ray diffraction test,which was found that methylene blue molecules were adsorbed on the surface when the CEC was lower(less than 40 mmol/100 g);When the CEC was higher(greater than 40 mmol/100 g),a large number of methylene blue molecules were absorbed between layers.Combined with the results of X ray diffraction,the results of the MB method are modified by the change of basal spacing(d_(001)).The results of the MB method are modified by empirical relation at low CEC and modified by d_(001) at high CEC,and good results are obtained.

关 键 词：阳离子交换量 亚甲基蓝法 黏性土 X射线衍射 晶层间距 

分 类 号：P574.1[天文地球—矿物学] TQ424[天文地球—地质学]