Ehrl Lyonel, Jia Zichen, Wu Hua, Lattuada Marco, Soos Miroslav, Morbidelli Massimo
Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland.
Langmuir. 2009 Mar 3;25(5):2696-702. doi: 10.1021/la803445y.
A generalized model for colloidal stability has been validated against experimentally measured values of Fuchs stability ratio and critical coagulation concentration (ccc) for electrolytes with mono- or divalent cation, i.e., potassium chloride and magnesium chloride, respectively. Besides the classical DLVO theory, the generalized model accounts for the interplay between colloidal interactions and the association of cations with the particles surface charge groups. The model parameters are either obtained or estimated purely on the basis of independent information available in the literature. For the monovalent salt, the predictions agree well with literature experimental data, forecasting both the ccc values and stability ratios quantitatively. For the divalent salt the predictions for large values of the stability ratio tend to deviate from the experimental data produced in this work, but it is noted that the onset of stability, i.e., the ccc, and small stability ratios are correctly predicted. Moreover, a comparison of the above results with those neglecting the effect of counterion association with the particles surface charge groups indicates that the latter substantially overestimates stability ratios in the presence of high salt concentration in the case of the monovalent salt, and leads to unrealistic large values of the ccc for the divalent salt. Including the association of cations with the particles surface charge groups can explain the relatively low values of experimental ccc for divalent salts compared to the theoretical predictions by the classical DLVO theory neglecting ion association, which is apoint of interest in industrial coagulation processes.
针对分别含有一价或二价阳离子（即氯化钾和氯化镁）的电解质，已根据富克斯稳定性比和临界凝聚浓度（ccc）的实验测量值验证了一种胶体稳定性的通用模型。除了经典的DLVO理论外，该通用模型还考虑了胶体相互作用与阳离子与颗粒表面电荷基团缔合之间的相互作用。模型参数完全基于文献中可用的独立信息获得或估计。对于单价盐，预测结果与文献实验数据吻合良好，能定量预测ccc值和稳定性比。对于二价盐，稳定性比大值的预测结果往往偏离本工作中产生的实验数据，但需要注意的是，稳定性的起始点（即ccc）和小稳定性比得到了正确预测。此外，将上述结果与忽略反离子与颗粒表面电荷基团缔合效应的结果进行比较表明，在单价盐存在高盐浓度的情况下，后者会大幅高估稳定性比，而对于二价盐则会导致ccc出现不切实际的大值。考虑阳离子与颗粒表面电荷基团的缔合可以解释与忽略离子缔合的经典DLVO理论的理论预测相比，二价盐实验ccc值相对较低的情况，这在工业凝聚过程中是一个值得关注的点。
