Effect of Surface Charge Density on the Affinity of Oxide Nanoparticles for the Vapor-Water Interface
Effect of Surface Charge Density on the Affinity of Oxide Nanoparticles for the Vapor-Water Interface
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DOI：
10.1021/la4005054
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发表时间：
2013-04-23
期刊：
影响因子：
3.9
通讯作者：
Abbas, Zareen
中科院分区：
文献类型：
--
作者：
Brown, Matthew A.;Duyckaerts, Nicolas;Abbas, Zareen
在蒸气-水界面使用原位 X 射线光电子能谱，显示纳米尺寸二氧化硅胶体在界面处的吸附亲和力取决于胶体表面电荷密度。在 pH 10 的水悬浮液中，校正表面络合计算的 Debye-Huckel 理论预测，较小的二氧化硅胶体会增加负表面电荷密度，这是由于凝聚离子层中的反离子对去质子化的硅烷醇基团（相当于 Si-O-）的增强筛选所致。负表面电荷密度的增加导致蒸汽-水界面的静电排斥，对于在 XPS 测量中电荷密度降低的较大颗粒而言，这种排斥程度较小。我们将原位 XPS 和修正的 Debye-Huckel 理论用于表面络合计算的结果和解释与传统的表面张力测量进行了比较。我们的结果表明，控制胶体颗粒的表面电荷密度可以调节它们对两种电介质之间界面的吸附。
Using in-situ X-ray photoelectron spectroscopy at the vapor-water interface, the affinity of nanometer-sized silica colloids to adsorb at the interface is shown to depend on colloid surface charge density. In aqueous suspensions at pH 10 corrected Debye-Huckel theory for surface complexation calculations predict that smaller silica colloids have increased negative surface charge density that originates from enhanced screening of deprotonated silanol groups (equivalent to Si-O-) by counterions in the condensed ion layer. The increased negative surface charge density results in an electrostatic repulsion from the vapor-water interface that is seen to a lesser extent for larger particles that have a reduced charge density in the XPS measurements. We compare the results and interpretation of the in-situ XPS and corrected Debye-Huckel theory for surface complexation calculations with traditional surface tension measurements. Our results show that controlling the surface charge density of colloid particles can regulate their adsorption to the interface between two dielectrics.