Compounds emulsion stability effect

Many dithiocarbamate complexes of zinc, silver, cadmium or mercury improve emulsion stability, including bis(dibenzyldithiocarbamato)-zinc(II) or -cadmium(II) and silver(I) diethyldi-thiocarbamate. Cadmium salts, mixed with citric acid or tartaric acid and added to the emulsion, are reported to be effective. Mercury(II) complexes of ethylenediaminetetraacetic acid (EDTA) and related ligands and of solubilized thiols such as (4) can be used. Other coordination compounds reported include EDTA and related ligand complexes of Co and Mn, mixtures of Co salts with penicillamine (5) and macrocyclic complexes of Ag such as (6). The latter compounds may be used in diffusion transfer systems in which transferred maximum densities are stabilized. 

Ronningsen et al. studied the aging of crude oils and its effect on the stability of emulsions (44). The oil was exposed to air and light and it was found that the interfacial tension of the oil towards formation of water decreased as a result of the aging. This was caused by the formation of various oxidation products, mainly carbonyl compounds. In general, the emulsions became more stable. In some cases, however, the opposite was observed, namely, that although the interfacial tension was high, the emulsion stability was lower, presumably because new compounds with less beneficial film properties are formed. Presumably, the compounds that were formed could be loosely classified as resins. 

A third approach is emulsification. Most emulsified commercial products are the oil-in-water type, in which the oil is suspended in the form of small spheres in the water. The oil is the discontinuous or internal phase, and the water is the continuous or external phase. Stabilization of these systems is effected by surface-active compounds that prevent the oil drops from coalescing and by proportioning the two phases so that the lighter phase cannot separate to the top. In applying the emulsion ap-... 

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