CrO_4^(2-)对两种可变电荷土壤表面电荷的影响

EFFECT OF CrO_4^(2-) ON SURFACE CHARGE OF VARIABLE CHARGE SOILS

对两种可变电荷土壤的研究结果表明,加入铬酸根(CrO42-)能增加土壤的表面负电荷,减小土壤的表面正电荷的量。CrO42-对表面正电荷的影响程度随体系pH的增加而减小,对负电荷的影响呈相反的趋势。CrO42-对表面电荷的影响程度也随其加入量的增加而增加。CrO42-主要通过自身的吸附来影响土壤的表面电荷,因为伴随着土壤表面电荷的变化,CrO42-在土壤中发生明显的吸附。而且土壤对CrO42-的吸附量随其加入量的增加而增加,随pH的升高而减小,与土壤电荷的变化趋势基本一致。

The presence of CrO42- induced increase in negative surface charge and decrease in positive surface charge of two variable charge soils. The effect on positive surface charge increased with the decrease in pH, while an opposite trend was observed for negative surface charge. The effect also increased with the level of CrO42- added. The mechanism of the effect may involve adsorption of CrO42- in the soils, because with the change in soil surface charge, CrO42- adsorption occurred in the soils. The quantity of CrO42- adsorbed by the soils also increased with the decrease in pH and the increase in level of CrO42- added, which was generally consistent with the change of soil surface charge.