用等温吸附法确定粘土表面吸附结合水界限

DETERMINATION OF BOUND WATER BOUNDARY ON CLAY SURFACE BY ISOTHERMAL ADSORPTION

采用等温吸附法对粘土表面吸附结合水量及其界限进行了定量测定,结果表明,随着相对水气平衡压p/ps的增加,在p/Ps=0～0.98时,纯蒙脱土吸附趋势均呈'S'形,表现为从单分子层吸附过渡为双层吸附、多层吸附,直到连续吸附.等温吸附曲线出现两个明显的转折点p/ps=0.9、0.98,它们为粘土-水体系的两个特征湿度,前者为粘土表面强结合水与松散结合水(渗透结合水)之间的交界点(界限),后者为松散结合水与自由水之间的交界点(界限).实验研究测得了粘土表面吸附结合水量(质量、体积、密度、厚度、平均积分比容等).配合X-射线衍射法,获得了水合粘土基面间距d001与p/ps的关系,验证了等温吸附法确定的两个特征湿度及对粘土表面结合水界限划分的正确性.

Isothermal adsorption is quantitatively utilized to determine types and boundary line of bound water on clays.Results show that pure montmorillonite adsorption tendency assume the type 'S' which is from single molecule layer adsorption to double layers adsorption,many layers adsorption and continuous adsorption along with relative vapor pressure p/p_s increasing(p/p_s=0～0.98).Isothermal adsorption curve have two clear turning points which are p/p_s =0.9 and p/p_s =0.98,standing for the special humidity of claywater system.The relative vapor pressure 0.9 is the boundary line between the strong bound water and the loose bound water(osmotic bound water) on clays,the relative vapor pressure 0.98 is the boundary line between the loose bound water and free water on clays.The experiment determines the bound water quantities on clays(mass,volume,density,thickness,average integral specific volume).The relationship between hydroclay datum face interval distance d_(001)and p/p_s has been obtained,and the two special humidity by isothermal adsorption and the boundary line of bound water on clays have been verified.