Colloidal stability factors affecting

Bailey, A.L, Cardenas-Valera, A.E., Graft copolymers as stabilizers for oil-imwater emulsions. Part 2. Preparation of the emulsions and the factors affecting their stability. Colloids and Surfaces, v.97, pp.1-12, 1995. 

McClements, D.J. (2005). Theoretical analysis of factors affecting the formation and stability of multilayered colloidal dispersions. Langmuir, 21, 9777-9785. 

Factors Affecting Stability There are numerous factors which affect the stability of a colloidal system. 

Very often, the microstructure and the macroscopic states of dispersions are determined by kinetic and thermodynamic considerations. While thermodynamics dictates what the equilibrium state will be, kinetics determine how fast that equilibrium state will be determined. While in thermodynamics the initial and final states must be determined, in kinetics the path and any energy barriers are important. The electrostatic and the electrical double-layer (the two charged portions of an inter cial region) play important roles in food emulsion stability. The Derjaguin-Landau-Verwey-Oveibeek (DLVO) theory of colloidal stability has been used to examine the factors affecting colloidal stability. 

The observation of Weilenmann et al. (1989) (see Figure 14.6) on some Swiss hard water lakes shows that two important factors affecting the stability of particles in lakes are (1) [Ca 1 and (2) organic matter (like humic substances). Ca destabilizes and organic matter stabilizes colloidal particles in lakes. 

Table 6.3. Factors affecting the stability of soil colloidal suspensions...

The colloidal stability issue associated with the extremely large oil-water interfacial area of latex particles has been covered in Chapter 2. Other important factors that affect the ultimate performance properties of water-based coating and printing systems are covered in this chapter, even though some of these critical issues might not be directly related to the emulsion polymers themselves. 

Boyd J, Parkinson C, Sherman P. 1972. Factors affecting emulsion stability and HLB concept. I Colloid Interface Sci 41(2) 359-370. 

Electrode kinetics, to be considered in the next chapter, are profoundly influenced by the structure of the double layer at an electrode-solution interface and it is with such systems that we shall be primarily concerned. However, double layer theory, as developed for electrode-electrolyte solution interfaces, leads on to the proper interpretation of electrokinetic phenomena, an understanding of the factors affecting colloid stability, and to the elucidation of cell membrane and ion-exchange processes. 

The factors that determine crystal size, a topic of particular relevance to this chapter, have been discussed to some extent in Section 3.4. There are two main factors that generally affect crystal size for any particular material the deposition mechanism and the deposition temperature. The hydroxide cluster mechanism is expected to give a crystal size similar to that of the original hydroxide cluster (with some growth possible as deposition proceeds). That size depends mainly on temperature, both because higher temperatures allow more grain growth and, possibly more important, lower temperatures kinetically stabilize very small nuclei in solution that are thermodynamically unstable. For example, in the hydroxide cluster mechanism, where crystal size is believed to be controlled mainly by the size of the Cd(OH)2 colloids, the relevant equilibria are... 

TABLE 5 Chemical Factors that Affect the Stability of Colloidal Suspensions... 

Other factors also affect the stability of eolloidal solutions, in particular the pH of the environment. The surface molecules of the nucleus of the micelles of different colloidal systems can have acid, basic, or amphoteric properties. Colloids characterized by this feature are called, respectively, acidosid, basoids, and ampholitoids (Marchenko, 1965). It has been established that the coagulation threshold of acidoids (sols of weak acids) increases and that of basoids decreases when the pH is increased. 

The clay component is the main factor controlling the rheological properties and the slip stability. Some part in this respect, hovewer, can also be played by the other very fine components. From the frit particles, water extracts alkalis which affect the colloidal and rheological properties of the slip. Since the extraction is gradual, the suspension is allowed to stand for a certain time before application to stabilize its properties. 

The effect of soil properties on the adsorption of substances. Physical and chemical characteristics of adsorbing components in the soil also affect the binding capacity and stability of chemical substances in the soil. The particle size is a further important factor. Colloidal particles exhibit the largest sorption capacity, with a diameter of 10 to 10 mm. The sorption capacity decreases with increasing size, and particles larger than 2 mm in diameter essentially do not affect the soil sorption capacity. From the chemical standpoint the soil sorbents may be divided into two groups ... 

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