Debye length, electrostatic colloidal forces

The concentration and nature of the electrolyte also has a significant impact on the stability of charged colloid dispersions. This was discussed in Section 3.3.2, where the concept of electric double layers was introduced. The electric double layer results from the atmosphere of counterions around a charged colloid particle. The decay of the potential in an electric double layer is governed by the Debye screening length, which is dependent on electrolyte concentration (Eq. 3.8). In the section that follows, the stability of charged colloids is analysed in terms of the balance between the electrostatic (repulsive) forces between double layers and the (predominantly attractive) van der Waals forces. 

There are various expressions for describing the electrostatic (typically) repulsive forces between colloidal particles but all of them indicate that the potential energy decreases exponentially with the distance and increases with increasing Debye length, relative permittivity and surface potential (see Table 10.5). Thus the key properties appearing in the various mathematical expressions are ... 

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