Surface Force Measurement between Oxide Surfaces in CnTACl Solutions Using an Atomic Force Microscope
An atomic force microscope has been used to measure the forces acting between two silica and two rutile surfaces in the presence and absence of cationic surfactants, CnTACl (n=12～18). The forces measured in the absence of surfactant can be fitted to the DLVO theory. At short separations,however, the silica surfaces exhibited repulsive hydration forces, while the rutile surfaces did not.On the other hand, the forces measured in the presence of the cationic surfactants show long-range attractions that are larger than the van der Waals forces. The long range attractions are the strongest at of the point of charge neutralization (p.c.n.), which decreases with increasing surfactant chain length. The possible origin of the long-range attraction has been tested in view of the charged-patch model of Miklavic et al. (1994). However, the sizes of the patches back-calculated from the model were much larger than those the patches (or hemi-micelles) determined experimentally and reported in the literature. It is, therefore, suggested that the long-range attractions observed in the present work are due to the structural response of the water molecules in the vicinity of hydrophobic surfaces.
Surface force AFM Long-range Attraction Hydrophobic force Point of charge neutralization Charged patch
J. H. Zhang R. H. Yoon
Department of Mining and Geological Engineering, The University of Arizona, Tucson, America Center for Advanced Separation Technologies, Virginia Tech, Blacksburg, America
国际会议
XXIV International Mineral Processing Congress(第24届国际矿物加工大会)
北京
英文
1019-1027
2008-09-24（万方平台首次上网日期，不代表论文的发表时间）