Department of Metallurgical Engineering, College of Mines and Earth Sciences, University of Utah, 135 South 1460 East, Room 412, Salt Lake City, UT 84112, USA.
Electron Microscopy Core Laboratory, University of Utah, 36 South Wasatch Drive, Ste:2500, USTAR Building, Salt Lake City, UT 84112, USA.
J Colloid Interface Sci. 2014 Apr 15;420:35-40. doi: 10.1016/j.jcis.2013.12.053. Epub 2014 Jan 3.
Fundamental results obtained from research on the properties of the edge surfaces of kaolinite particles (~500 nm) are reported. Of particular significance was the development of the experimental protocol. Well-ordered kaolinite edge surfaces were prepared as an epoxy resin sandwich structure having layered kaolinite particles in the center of the epoxy resin sandwich. Images of the sectioned kaolinite edge surfaces were examined by atomic force microscopy (AFM), and the average thickness of kaolinite particles in this study was determined to be 38.3 nm±11.7 nm. Furthermore, the surface charge of the kaolinite edge surfaces was evaluated with a super sharp Si tip. The point of zero charge (PZC) of the kaolinite edge surface was determined to be below pH 4, in contrast to the traditional view that the edge surfaces of kaolinite particles may carry a positive charge at pH 4. This lower PZC of the kaolinite edge surface was attributed to the lack of isomorphous substitution in the silica tetrahedral layer when compared to the PZC for the muscovite edge surface. Our results are consistent with the particle aggregation and flotation behavior of kaolinite, and should provide the basis for improved flotation strategies leading to the efficient recovery and utilization of mineral and energy resources.
本文报道了对高岭石颗粒 (~500nm) 边缘表面特性进行研究得到的基本结果。特别重要的是实验方案的制定。有序的高岭石边缘表面被制备为具有层状高岭石颗粒的环氧树脂夹层结构。通过原子力显微镜 (AFM) 对切片的高岭石边缘表面图像进行了检查，本研究中高岭石颗粒的平均厚度确定为 38.3nm±11.7nm。此外，还使用超锋利的 Si 尖端评估了高岭石边缘表面的表面电荷。高岭石边缘表面的零电荷点 (PZC) 被确定为 pH 值低于 4，与传统观点相反，即高岭石颗粒的边缘表面在 pH 值为 4 时可能带正电荷。与云母边缘表面的 PZC 相比，高岭石边缘表面的 PZC 较低，这归因于硅四面体层中没有同晶取代。我们的结果与高岭石的颗粒聚集和浮选行为一致，应为改进浮选策略提供基础，从而实现矿物和能源资源的有效回收和利用。
