Effect of Surface Charge on Colloidal Charge Reversal
Effect of Surface Charge on Colloidal Charge Reversal
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DOI：
10.1021/jp900959y
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发表时间：
2009-05-14
影响因子：
3.3
通讯作者：
Quesada-Perez, M.
中科院分区：
文献类型：
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作者：
Martin-Molina, A.;Rodriguez-Beas, C.;Quesada-Perez, M.
本研究的目的是了解表面电荷密度对电荷反转现象的影响。为此，我们使用实验结果和计算机模拟。特别是，我们测量的电泳迁移率的乳胶粒子（大离子）的存在下的多价电解质。我们已经集中在电解质浓度范围内，在该范围内，预期会发生电泳迁移率的逆转。特别是，电荷反转过程中的表面电荷的作用，从几个具有相同的功能团，但不同的表面电荷密度的胶乳看。虽然负责的胶体电荷反转的机制仍然是一个有争议的问题，它被证明是离子相关的背后出现这种现象（特别是在宏观离子表面附近）。这一结论可以从各种各样的理论模型中推断出来。根据他们的观点，决定电荷反转的因素之一是大离子的表面电荷密度。然而，这一特性很少在实验中得到分析。因此，我们的结果似乎是一个必要的调查，以测试理论预测的有效性。此外，我们还进行了Monte Carlo模拟，考虑到离子的大小。实验和模拟之间的相关性相当好。这些技术的结合提供了新的洞察胶体电荷反转现象显示的表面电荷的影响。
The objective of this research work is to understand the effect of the surface charge density on the charge reversal phenomenon. To this end, we use experimental results and computer simulations. In particular, we measure the electrophoretic mobility of latex particles (macroions) in the presence of a multivalent electrolyte. We have focused on the electrolyte concentration range at which a reversal in the electrophoretic mobility is expected to happen. In particular, the role of the surface charge on the charge reversal process is looked into from several latexes with the same functional group but different surface charge densities. Although the mechanism responsible for the colloidal charge reversal is still a controversial issue, it is proved that ionic correlations are behind the appearance of such phenomenon (especially near the macroion surface). This conclusion can be inferred from a great variety of theoretical models. According to them, one of the factors that determine the charge reversal is the surface charge density of the macroions. However, this feature has been rarely analyzed in experiments. Our results appear therefore as a demanded survey to test the validity of the theoretical predictions. Moreover, we have also performed Monte Carlo simulations that take the ion size into account. The correlation found between experiments and simulations is fairly good. The combination of these techniques provides new insight into the colloidal charge reversal phenomena showing the effect of surface charge.