摘要
本文研究了我国8种主要膨润土的表面性质。研究结果表明,8种膨润土的比表面值为465—676m^2/g,表面负电荷量为45.6—66.5meq/100g。膨润土的比表面和表面负电荷量与其蒙脱石含量呈显著正相关,相关系数分别为0.874^(**)和0.968^(**)两种钙钠质膨润土在焙烧温度400℃时,钙质仇山膨润土负电荷量降低约40%,而钠质平山膨润土无明显变化;后者只在500—600℃时才表现出明显的降低。这说明,膨润土比表面和表面负电荷量主要由其所含的矿物类型决定的。而它们的耐用性则主要取决于其表面吸附的离子类型,钠质膨润土的耐用性高于钙质膨润土。
The surface characteristics of 8 main kinds of bentonite in China are dealt with in this paper. The samples include 5 Ca-bentonites taken from Jiutai of Jilin,Longquan of Jiangsu,Choushan of Zhejiang,Xinyang of Henan and Heishan of Liaoning respectively and 3 Nabentonites collected from Pingshan of zhejiang and Toksun and Xiazijie of Xinjiang.And the bentonite sample from Wyoming,USA was used as a check.Results show that the specific surface area of the 8 bentonites ranged from 465 to 676m^2/g,among which the bentonites from Xinyang,Jiutai and Toksun were the highest while that from Pingshan the lowest.Their surface negative charge vatied between 45.6 and 66.5meq/1OOg,tbe samples from Longquan,Jiutai,Xinyang,Toksun and Xiazijie were all higher than 50meq/1OOg.Studies also show that the specific surface area and surface negative charge of the bentonites were highly posicively tortelated with its montmorillonite content,r=0.874^(**)and 0.968(**) respecti vely.All the 8 kinds of bentonites Studied,except those from Pingshan and Choushan,had a montmorillonite eontent higher than 60meq/1OOg.The bentonites from Toksun and Xinyang had higher specific surface area and surface negative charge than that from Wyoming,suggesting tbat these bentonites are valuable clay minerals for industrial use.The influence of the roasting temperature on the surface characteristics was also studied.It has been revealed that the surface negative charge of the Choushan bentonite was negatively correlated with the roasting temperature, which may be illustrated by the equation:NC=ae^(-be)(NC--surface negative charge,τ——the roasting ternperature,a,b—constant),with a correlation coefficient of —0.8708~*.The surface negative charge of Ca-bentonites decreased progressively as the temperature rose,showing no sudden change.For the Na-bentonites,in contrast,when the roasting ternperature was<500℃,increasing the temperature gave no maked reduction in its surface negative charge.When the temperature exceeded 500℃,however,the surface negative charge dropped abruptly. Even at 600℃ when the clay mineral was dehydrated and broken downt, the Pingshan bentonite was still higher in surface negative charge than the Choushan one.The general trend that the specific surface area of the Choushan and Pingshan bentonites varied with the increase of roasting temperature is rather similar to the case of their surface negative charge.It can thus be seen that the Na-bentonite has a higher durability than the Ca-bentonite.
出处
《土壤学报》
CAS
CSCD
北大核心
1991年第2期155-160,共6页
Acta Pedologica Sinica
