Mapping and Quantifying Surface Charges on Clay Nanoparticles

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• 作者：Jun Liu ; Ravi Gaikwad ; Aharnish Hande ; Siddhartha Das ; Thomas Thundat
• 刊名：Langmuir
• 出版年：2015
• 出版时间：September 29, 2015
• 年：2015
• 卷：31
• 期：38
• 页码：10469-10476
• 全文大小：599K
• ISSN：1520-5827

文摘

Understanding the electrical properties of clay nanoparticles is very important since they play a crucial role in every aspect of oil sands processing, from bitumen extraction to sedimentation in mature fine tailings (MFT). Here, we report the direct mapping and quantification of surface charges on clay nanoparticles using Kelvin probe force microscopy (KPFM) and electrostatic force microscopy (EFM). The morphology of clean kaolinite clay nanoparticles shows a layered structure, while the corresponding surface potential map shows a layer-dependent charge distribution. More importantly, a surface charge density of 25 nC/cm² was estimated for clean kaolinite layers by using EFM measurements. On the other hand, the EFM measurements show that the clay particles obtained from the tailings demonstrate a reduced surface charge density of 7 nC/cm², which may be possibly attributed to the presence of various bituminous compounds residing on the clay surfaces.