Derjaguin—Landau—Verwey—Overbeek theory

The DLVO (Derjaguin-Landau-Verwey-Overbeek) theory describes the stability of a colloidal suspension as mainly dependent on the distance between the particles... 

THE DERJAGUIN-LANDAU-VERWEY-OVERBEEK THEORY OF COLLOID STABILITY... 

What is the Derjaguin-Landau-Verwey-Overbeek theory ... 

DLVO theory (Derjaguin-Landau-Verwey-Overbeek theory) — The DLVO theory is named after Derjaguin and Landau [i], and Verwey and Overbeek [ii]. It describes the forces acting between colloidal particles in... 

The d vs. c mapping enables us to make a comparison between the coulombic attraction theory and DLVO (Derjaguin-Landau-Verwey-Overbeek) theory over the whole two-phase region. As we saw in Chapter 2, the leading predictions of the two theories are as follows. 

The classical intuition on molecular forces is embodied in the famous Derjaguin-Landau-Verwey-Overbeek theory of colloid stability. It blends themes (i) and (ii) above in a contradictory way that has taken imtil the last few years to sort out. 

Earlier experimental and theoretical studies of systems in which particles interact through Van der Waal s attraction and electrostatic repulsion led to the development of Derjaguin-Landau-Verwey-Overbeek theory (DLVO). This theory has been successful in providing a quan-... 

The role of electrostatic repulsion in the stability of suspensions of particles in non-aqueous media is not yet clear. In order to attempt to apply theories such as the DLVO (Derjaguin-Landau-Verwey-Overbeek) theory (to be introduced in Section 5.2), one must know the electrical potential at the surface, the Hamaker constant and the ionic strength to be used for the non-aqueous medium these are difficult to estimate. The ionic strength will be low so the EDL will be thick, the electric potential will vary slowly with separation distance and so will the net electric potential as the double layers overlap. For this reason, the repulsion between particles can be expected to be weak. A summary of work on the applicability or lack of applicability of DLVO theory to non-aqueous media has been given by Morrison [33]. 

The principles of colloid stability, including DLVO (Derjaguin—Landau—Verwey— Overbeek) theory, disjoining pressure, the Marangoni effect, surface viscosity and steric stabilization, can be usefully applied to many food systems [23, 33]. Walstra [33] provides some examples of DLVO calculations, steric stabilization and bridging flocculation for food colloid systems. 

Abstract. The stability of suspensions/emulsions is under consideration. Traditionally consideration of colloidal systems is based on inclusion only Van-der-Waals (or dispersion) and electrostatic components, which is refereed to as DLVO (Derjaguin-Landau-Verwey-Overbeek) theory. It is shown that not only DLVO components but also other types of the inter-particle forces may play an important role in the stability and colloidal systems. Those contributions are due to hydrodynamic interactions, hydration and hydrophobic forces, steric and depletion forced, oscillatory structural forces. The hydrodynamic and colloidal interactions between drops and bubbles emulsions and foams are even more complex (as compared to that of suspensions of solid particles) due to the fluidity and deformability of those colloidal objects. The latter two features and thin film formation between the colliding particles have a great impact on the hydrodynamic interactions, the magnitude of the disjoining pressure and on the dynamic and thermodynamic stability of such colloidal systems. 

The valence of the counterion is the predominant influence in preventing coagulation of a colloidal dispersion. The nature of the counterion, the valence of the co-ion and the concentration of the sol are much less important, and the nature of the sol only has a moderate effect on stability. These empirical observations, made in the late nineteenth century, are known as the Schulze-Hardy rule. We are now able to interpret these effects using a quantitative model known as the Derjaguin-Landau-Verwey-Overbeek theory, discussed in the next section. 

For many decades, DLVO (Derjaguin-Landau-Verwey-Overbeek) theory has been used to describe interactions between colloidal systems. Indeed it is a very successful theory which can reproduce many phenomena. However, specific ion effects are not taken into account in this theory. This has different reasons DLVO consists of a sum of electrostatic and van der Waals interactions. As Ninham pointed out, this combination is not made in a rigorous way. We will discuss this in Sec. 2. 

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