Department of Food Engineering, University of Bio-Bio, Chillán, Chile.
J Colloid Interface Sci. 2011 Sep 1;361(1):397-9. doi: 10.1016/j.jcis.2011.05.063. Epub 2011 May 26.
Nanoscale repulsive forces between mineral surfaces in aqueous solutions were measured for the asymmetric mica-silica system. The force measured with an atomic force microscope (AFM) has universal character in the short range, less than ∼1 nm or about 3-4 water molecules, independent of solution conditions, that is, electrolyte ion (Na, Ca, Al), concentration (10(-6)-10(-2)M), and pH (3.9-8.2). Notably, the force is essentially the same as for the glass-silica system. Single force curves for a mica-silica system in a 10(-4)M aqueous NaCl solution at pH ∼ 5.1 show oscillations with a period of about 0.25 nm, roughly the diameter of a water molecule, a consequence of a layer-by-layer dehydration of the surfaces when pushed together. This result provides additional support to the idea that nanoscale repulsive forces between mineral surfaces in aqueous solutions arise from a surface-induced water effect; the water between two mineral plates that are pushed together becomes structured and increasingly anchored to the surface of the plates by the creation of a hydrogen-bonding network that prevents dehydration of the surfaces.
在水溶液中，对非对称云母-硅石系统进行了纳米级表面斥力的测量。原子力显微镜（AFM）测量的力在短程范围内具有普遍特征，小于约 1nm 或约 3-4 个水分子，与溶液条件无关，即电解质离子（Na、Ca、Al）、浓度（10(-6)-10(-2)M）和 pH（3.9-8.2）。值得注意的是，该力与玻璃-硅石系统基本相同。在 pH 值约为 5.1 的 10(-4)M 水溶液中 NaCl 溶液中，云母-硅石系统的单个力曲线显示出约 0.25nm 的周期性振荡，大致是一个水分子的直径，这是由于表面在相互挤压时逐层脱水所致。这一结果为纳米级水溶液中矿物表面之间的排斥力源于表面诱导水效应的观点提供了额外的支持；当两个被挤压在一起的矿物板之间的水变得结构化，并通过氢键网络的形成越来越多地固定在板的表面上，从而阻止了表面的脱水。
