Determination of the solvation film thickness of dispersed particles with the method of Einstein viscosity equation

Changsheng Peng, Shaoxian Song, and Shouci Lu College of Environmental Science and Engineering, Ocean University of China, Qingdao 266003, China Instituto de Metalurgia, Universidad Aut(o，¨)noma de San Luis Potosí, Av. Sierra Leona 550, San Luis Potosí, C.P. 78210, Mexico Civil and Environmental Engineering School, University of Science and Technology Beijing, Beijing 100083, China

摘 要：<正>The dispersion of a solid particle in a liquid may lead to the formation of solvation film on the particle surface, which can strongly increase the repulsive force between particles and thus strongly affect the stability of dispersions. The solvation film thickness, which varies with the variation of the property of suspension particles and solutions, is one of the most important parameters of the solvation film, and is also one of the most difficult parameters that can be measured accurately. In this paper, a method, based on the Einstein viscosity equation of dispersions, for determining the solvation film thickness of particles is developed. This method was tested on two kinds of silica spherical powders （namely M1 and M2） dispersed in ethyl alcohol, in water, and in a water-ethyl alcohol mixture （1:1 by volume） through measuring the relative viscosity of dispersions of the particles as a function of the volume fraction of the dry particles in the dispersion, and of the specific surface area and the density of the particles. The calculated solvation film thicknesses on Ml are 7.48, 18.65 and 23.74 nm in alcohol, water and the water-ethyl alcohol mixture, 12.41, 12.71 and 13.13 nm on M2 in alcohol, water and the water-ethyl alcohol mixture, respectively.

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