Effect of anionic surfactants on the stability ratio and electrophoretic mobility of colloidal hematite particles
Effect of anionic surfactants on the stability ratio and electrophoretic mobility of colloidal hematite particles
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DOI：
10.1016/j.colsurfa.2016.07.063
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发表时间：
2016-12-05
影响因子：
5.2
通讯作者：
Adachi, Yasuhisa
中科院分区：
文献类型：
--
作者：
Kobayashi, Motoyoshi;Yuki, Shunzo;Adachi, Yasuhisa
研究了阴离子表面活性剂对赤铁矿颗粒带电和聚集的影响。通过对电泳迁移率的测量和分析，研究了充电行为。从浑浊度的时间变化得到了赤铁矿悬浮液的稳定比，并用DLVO理论对稳定比进行了分析。以表面活性剂的种类、用量和链长为函数进行实验。赤铁矿在pH值低于7时，其电泳迁移率为正。随着表面活性剂用量的增加，迁移率逐渐变为负值。达到等电点所需的表面活性剂浓度随着表面活性剂链长的增加而降低。这些结果可以用一个简单的理论模型来合理地描述。稳定比在等电点附近最小。也就是说，由于表面活性剂吸附在赤铁矿上，电荷中和使悬浮液不稳定。无论链长如何，最小稳定比的值几乎一致；表面活性剂的最快聚集速率等于盐诱导的速率。因此，在离子表面活性剂的情况下，电荷贴片吸引和空间位阻在零迁移率浓度附近不明显起作用。DLVO理论定性地描述了聚合行为。脂肪酸悬浮液的最小稳定比范围较窄。结果表明，含脂肪酸的悬浮液稳定性较好。(C) 2016 Elsevier B.V.版权所有
The effect of anionic surfactants on the charging and aggregation of hematite particles was investigated. Charging behavior was studied by the measurement and analysis of the electrophoretic mobility. The stability ratio of hematite suspension was obtained from the temporal change of turbidity, and the stability ratio was analyzed by the DLVO theory. These experiments were performed as functions of types of surfactant, surfactant dosage, and surfactant chain length. Electrophoretic mobility of bare hematite was positive at pH below 7. The mobility went through zero and became negative with increasing surfactant dosage. Required surfactant concentrations reaching the isoelectric point decreased with increasing the chain length of surfactant. These results are reasonably described by a simple theoretical model. The stability ratio showed the minimum around the isoelectric point. That is, the suspension is destabilized by charge neutralization due to the adsorption of surfactants onto the hematite. Values of the minimum stability ratio in this work were almost unity irrespective of the chain length; the fastest aggregation rate with surfactants equaled the salt-induced rate. Therefore, in the case of ionic-surfactant, charge-patch attraction and steric hindrance do not significantly work around zero mobility concentration. The DLVO theory qualitatively describes the aggregation behavior. The range of the minimum stability ratio was narrower for the suspension with fatty acids. This result indicates that the suspension with fatty acids is more stable. (C) 2016 Elsevier B.V. All rights reserved.