Influence of Semibatch Emulsification Process Conditions on The Physical Characteristics of Highly Concentrated Water-in-Oil Emulsions

Abstract

We studied the energy consumption per unit volume during preparation of highly concentrated water-in-oil emulsions in a two-step semibatch process. In particular, we studied the effect of two process variables, the water addition flow rate (Q w ) and the agitation speed (N). The oil used for emulsion preparation was n-dodecane, the surfactant was sorbitan monooleate (Span 80) and deionized water was used for the dispersed phase. The results obtained showed that two steps were required to get complete incorporation of the dispersed phase and a homogeneous and stable gel-emulsion. With the help of independent physical characteristics measurement performed at the end of the preparation process, we established two functional relationships, relating storage modulus (G′) with energy consumption (E v ), (G′ ∝ E v 0.6 ), and average liquid cell size (R m ) of the dispersed phase with energy consumption (E v ), (R m ∝ E V -0.3 ). A structural scaling law can be deduced that relates the elastic modulus to the reciprocal of the square of the average liquid's cell size of the gel-emulsion, corroborated by independent measurements and predicted by recent published models.

The application of a multi-scale approach to the manufacture of concentrated and highly concentrated emulsions

“…It is important to highlight the fact that the energy incorporated through the emulsification process corresponds to the energy that is required to homogenize the product after the dispersed phase has been added. In the preparation of concentrated and highly concentrated emulsions, this stage requires more energy than the incorporation step (Alvarez et al, 2010). Different publications have reported that when the volume fraction of the dispersed phase increases, the elasticity of the concentrated and highly concentrated emulsions also increases (Salager, 1996;Langevin, 2000;Dimitrova and LealCalderon, 2004;Pal, 2006).…”

“…The tip velocity was also kept constant to assure that the same shear was given by impellers with different diameters. Second, the stage of the emulsification process that demands the most energy is the homogenization step (Alvarez et al, 2010).…”

“…Different authors (Salager, 1996;Tadros, 2004;Alvarez et al, 2010;Capdevila et al, 2010) have implicated the tip velocity as a key factor in the emulsification process, mainly because this factor can control the amount of shear available for droplet formation. If we now take into consideration the results presented in Figs.…”

“…If we now look more closely at the relationships between the incorporated energy and the rheological behavior (that is, the microscopic structure and the molecular response), we can follow an approach similar to the one proposed by Alvarez (Alvarez et al, 2010) and establish equations similar to Eqs.…”

“…Using a similar approach, Alvarez et al (2010) established a relationship between the energy incorporated through the emulsification process and the macroscopic properties (the rheology) of water-in-oil (W/O) emulsions. They also established a second relationship that relates the energy incorporated to the microscopic structure of the system (the average droplet size).…”