Anion-specific effects on the interaction forces between Al₂O₃ surfaces and dispersibility of Al₂O₃ colloids in electrolyte solutions

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• 作者：Toshihiro Isobe ; ^{isobe.t.ad@m.titech.ac.jp} ; Yosuke Nakagawa ; Mikiro Hayashi ; Sachiko Matsushita ; Akira Nakajima
• 关键词：Atomic force microscopy ; Force curve ; DLVO theory
• 刊名：Colloids and Surfaces A ; Physicochemical and Engineering Aspects
• 出版年：2012
• 期刊代码：22_09277757
• 类别：ch
• 出版时间：20 February, 2012
• 卷：396
• 期：Complete
• 页码：233-237
• 文件大小：593 K

摘要

The interaction between an Al₂O₃ colloid and c-sapphire surface (0 0 0 1) was investigated in an aqueous solution containing citrate ion, Cl^{鈭?/sup>, NO₃鈭?/sup> or Br鈭?/sup> using the colloidal probe method. The force curve measured in electrolyte solutions at pH = 4 showed a good agreement with the force curve predicted by the Derjaguin-Landau-Vervey-Overbeek theory at a long separation distance. The repulsive forces were observed at a shorter separation distance. The order of the strength of the repulsive force was citrate ion > Cl鈭?/sup> > NO₃鈭?/sup> > Br鈭?/sup>, corresponding to the Hofmeister series. All the force curves measured in aqueous solutions at pH = 10 were the same. This is caused by the cation (K+) selectively affecting surface interaction because the Al₂O₃ surface charged to negative at this pH. A particle size distribution measurement of the Al₂O₃ colloids in the 0.001-0.1 mol/L Cl鈭?/sup> and Br鈭?/sup> aqueous solution was carried out. The agglomerates of the Al₂O₃ colloids were observed in 0.1 mol/L Br鈭?/sup> solutions. However, Al₂O₃ colloids were well dispersed in the other aqueous solutions, which are reflected by the force curve results. Jump-in was observed only in the force curve measured in the 0.1 mol/L Br鈭?/sup> solutions and not in any other solutions.}