Emulsification procedures

The presence of oil from certain texturing, knitting, or other operation can lead to oil-bound deposits caking the air washer systems or to heavy foaming. Demulsification and subsequent oil removal by skimming is preferred to emulsification procedures. 

There is some evidence to suggest that, depending upon the phase volume ratios employed, the emulsification technique used can be of greater importance in determining the final emulsion type than the H LB values of the surfactants themselves [434], As an empirical scale the HLB values are determined by a standardized test procedure. However, the HLB classification for oil phases in terms of the required HLB values is apparently greatly dependent on the emulsification conditions and process for some phase-volume ratios. When an emulsification procedure involves high shear, or when a 50/50 phase volume ratio is used, interpretations based on the classical HLB system appear to remain valid. However, at other phase-volume ratios and especially under low shear emulsification conditions, inverted, concentrated emulsions may form at unexpected HLB values [434]. This is illustrated in Figures 7.4 and 7.5. 

The various membrane emulsification procedure can be practised by using appropriate membranes and devices configuration. 

Figure 6 Oil droplet size distribution of on olive oil emulsion, stabilized with hydroxy-propyl mcthylceUkiloae, after different emulsification procedures blender (triangles), ultrasonic probe (squares), and ultrasonic homogenize (stars). Theoretical distributions were calculated from Coulter Counter measurements using a software program, assuming spherical particles.

The above argument suggests that the initial droplet size distribution may play an important role in super-swelling or colloidal instability. This indicates that one should monitor the emulsification procedure for controlled free radical emulsion polymerization closely. 

Finally, under well-defined conditions, it is possible to polymerize performed emulsion droplets. This is especially true for emulsions prepared by condensation methods where the conditions can be controlled in such a way that both secondary nucleation can be avoided and droplet or particle stability can be maintained during the entire polymerization. In the case of emulsions prepared by comminution techniques, suspension polymerization is a good example of a system where the (conditions) properties of emulsions can be converted into the corresponding properties of sols/suspensions. For smaller drop sizes, the solubility of the monomer in water is crucial, but unfortunately, very hydrophobic monomers are technically unimportant, at least nowadays. The addition of hydrophobic molecules needs tailored emulsification procedures regarding and DSD, and a certain maturation time to result in stable emulsions. Miniemulsion polymerization is a promising way, although the question as to what extent a 1 1 copy of an emulsion is possible is still waiting for an answer. 

C. Wischke, H.-H. Borchert, Influence of tile primary emulsification procedure on tile characteristics of small protein-loaded PLGA microparticles for antigen delivery, J. Microencaps. 2006, 23, 435 48. 

We developed a lipiodol W/O/W emulsion that encapsulates a water-soluble anticancer agent by using a two-step pumping emulsification procedure (Hino et al., 1995). We were able to investigate the acute toxicity and deposition of the agent and lipiodol in liver after i.v. and hepatic arterial administration of the emulsion to rats (Hino et al., 1997,1999). 

An optical microphotograph of our prepared W/O/W emulsion is shown in Figure 11.5. The same W/O/W emulsion could be prepared by a two-step pumping emulsification procedure under sterilized conditions to avoid contamination. 

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