Agglomeration, droplet, first step

Agglomeration, droplet, first step in demulsification, 44 Aggregation definition, 6-7, 386 droplet, kinetics and methods of preventing, 36... 

Some emulsions are undesirable when they occur. In process industries chemical demulsification is commonly used to separate water from oil in order to produce a fluid suitable for further processing. The specific kind of emulsion treatment required can be highly variable, even within the same industry. The first step in systematic emulsion breaking is to characterize the emulsion in terms of its nature (O/W, W/O, or multiple emulsion), the number and nature of immiscible phases, the presence of a protective interfacial film around the droplets, and the sensitivity of the emulsifiers [295,408,451], Demulsification then involves two steps. First, there must be agglomeration or coagulation of droplets. Then, the agglomerated droplets must coalesce. Only after these two steps can complete phase separation occur. It should be realized that either step can be rate determining for the demulsification process. 

The Microemulsion method is a novel route for the formation of NPs. A microemulsion is a cloudy colloidal system of micron size droplets of one immiscible hquid dispersed in another, such as oil in water, in the presence of a suitable surfactant and a co-surfactant. A microemulsion is formed by vigorous stirring or sonication and is thermod)mamically stable. Nanosize particles can spontaneously form within the micron size water droplets as a thermodynamically stable microemulsion. Briefly, in this method the first step is the formation of NP through a water-in-oil microemulsion reaction, followed by a reduction step. The surfactant molecules can function as protective agents to prevent the NP from agglomeration [15,21]. The surfactant molecule can be easily removed by heat treatment. The main advantage of the microemulsion method is its controlling metallic composition and particle size with a narrow distribution [29]. FC catalysts, particularly Pt-Ru, have been prepared by this novel route [30,31]. 

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