摘要
对用电位滴定法 (PT法 )测定的胶体颗粒零电荷点 (ZPC)的物理意义进行了理论分析 ,认为是零净电荷点(pHZPNC) ,推导出了pHZPNC、零可变电荷点 (pHZPVC)、永久电荷密度 (σp)、可变电荷密度 (σv)、净电荷密度 (σT)、pH和电解质浓度 (c)之间的理论关系式 .用PT法测得高岭土的pHZPNC 和σp 分别为 3.12和 - 0 .0 5 1mmol·g- 1 ;pHZPVC 比pHZPNC 高 ,pHZPVC随c增大而减小 ;σT 和σv 的负值随pH和c的增大而增大 .
The theoretical analysis on the zero point of charge (ZPC) and charge density of colloidal particle possessing permanent charges indicates that ZPC determined directly by means of potentiometric titration (PT) should be zero point of net charge (ZPNC) and the permanent charge density ( σ P) can be obtained from the adsorption amounts of H + and OH -( Γ OH - Γ H ) at ZPNC. ZPNC does not change with the electrolyte concentration ( c ), whereas the zero point of variable charge (ZPVC) changes with c . When σ P is at zero, ZPNC equals to ZPVC, and only under this condition is ZPC measured directly by PT equal to ZPVC. The relationship among ZPNC, ZNVC, σ P, the variable charge density ( σ V), the total net surface charge density ( σ T), pH, and c is derived. ZPNC and σ P of kaolinite are determined by PT method. It is found that the ZPNC is at pH=3.12 and the σ P is -0.051mmol·g -1 , the ZPNC is lower than ZPVC, and the ZPVC decreases with the increase of the c , while negtive σ T and σ V increase with the increase of pH and the c .
出处
《山东大学学报（理学版）》
CAS
CSCD
北大核心
2003年第1期86-88,92,共4页
Journal of Shandong University(Natural Science)
基金
国家自然科学基金 (2 0 2 73 0 41)
山东省自然科学基金 (Y97B0 10 2 4)
教育部资助课题
关键词
零电荷点
电荷密度
高岭土
电位滴定法
zero point of charge
charge density
kaolinite
potentiometric titration
