Electrical Forces Affecting Soil and Substrate in the Detergency Process—Zeta Potential

Electrokinetic forces are of considerable importance in the mechanism of soil removal and redeposition. One electrokinetic measurement is that of the difference in potential between the immovable layer attached to the surface of a solid phase (soil or substrate) and the movable part of the diffuse layer in the body of the detergent liquid, and is termed zeta potential. Correlations have been obtained which indicate that, in a de tergent system, it is desirable that the zeta potentials of soil particles and substrate become nearly equal to reduce attractive forces tending to cause them to adhere.

The effect of surfactants and electrolytes upon the zeta potential of soils and sub strates has been collated, permitting an estimate of the areas in need of further elucida tion. Cited are available correlations between zeta potential and suspension values, critical micelle concentration, and detergency values.