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近年来,电导在土壤研究中有着非常广泛的应用,它可能作为揭示土壤胶体颗粒表面与离子之间相互作用的一种有效工具.在该研究中,将不同浓度的KNO3分别加入土壤胶体悬液和水体系后测定体系电导率和pH值,研究了土壤表面电荷与离子间的相互作用对悬液电导的影响,结果发现:1)随体系电解质浓度增加,胶体表面可变负电荷的数量增加,胶粒电导增加;2)KNO3的水解使得加入的KNO3浓度越高,悬液体系的pH值越低;3)决定可变电荷体系表面负电荷多少的关键并不是H+的活度的高低,而是表面静电吸附中H+与盐基阳离子的相对竞争力的强弱,即低的pH值并不一定导致表面负电荷数量降低;4)在研究电解质对可变电荷胶体表面电荷的影响时,不能忽略离子水解对表面电荷性质影响的间接效应.
In recent years, conductivity has been widely used in soil research and it may be used as an effective tool to reveal the interaction between soil colloidal particle surface and ions.In this study, different concentrations of KNO3 were added to the soil colloidal suspension And water system, the influence of the interaction between soil surface charges and ions on the conductance of the suspension was studied. The results showed that: 1) With the increase of the electrolyte concentration of the system, the amount of negative charge on the surface of the colloid increased And the conductivity of colloidal particles increases; 2) The hydrolysis of KNO3 makes the concentration of KNO3 increased, the lower the pH value of the suspension system; 3) the key to determine the negative charge on the surface of the variable charge system is not H + activity, But rather the relative competitive power between H + and the salt-based cation in surface electrostatic adsorption. That is, the low pH does not necessarily lead to the decrease of the number of negative charges on the surface. 4) When studying the effect of electrolyte on the surface charge of variable charge colloids, Indirect effects of ionic hydrolysis on the surface charge properties can not be ignored.