Interfacial aspects of water drop formation at micro-engineered orifices

Controlled production of oil-in-water emulsions containing unrefined pumpkin seed oil using stirred cell membrane emulsification

“…As can be seen, the smaller drops are formed in the presence of Tween 20, which is a consequence of the lower equilibrium interfacial tension ( = 1.5 and 6 mN m -1 for 2 wt.% Tween 20 and Pluronic F-68, respectively, see [40]. On the other hand, the dynamic interfacial tension linearly increases with (Dt) 0.5 [35,37]. Figure 11 clearly shows that the size of pumpkin oil drops can effectively be reduced by increasing the concentration of Pluronic F-68 from 2 to 10 wt.%, which is slightly above a CMC value of 9.2 wt.…”

“…Hence, the increase of dispersed phase flux results in an increase in the amount of oil flowed into a drop during the detachment process, and the formation of larger droplets [33]. In addition, when the dispersed phase flux is increased, the drop grows faster and the interface cannot be stabilized fast enough by adsorbed emulsifier molecules, as pointed out by some authors [34,35]. A higher interfacial tension force keeps the drop attached to the pore for a longer time, leading to a greater drop size at snap-off.…”

Microencapsulation of oil droplets using cold water fish gelatine/gum arabic complex coacervation by membrane emulsification

“…The droplet size increase with dispersed phase flux can be explained considering that the increase of dispersed phase flux results in an increase in the volume of oil flowing through the membrane pores during the detachment process, and the formation of larger droplets (Xu et al, 2005). In addition, when the dispersed phase flux is increased, the drop grows faster and larger droplets are generated as a consequence of the lower concentration of the polymers at the interface in the growth phase (Schröder et al, 1998;Geerken et al, 2007). Figure 11 shows that uniformly sized drops with a span value less than 0.5 were obtained at oil flow rate of 5.6 mL min ) and oil concentration (32% v/v) where low amount of biopolymer was available in the aqueous solution to completely cover all of the oil droplets surface that were quickly generated at the membrane pore interface.…”

Droplet formation in microfluidic T-junction generators operating in the transitional regime. III. Dynamic surfactant effects

“…A considerable amount of work has documented the effects of surfactant dynamics on the production of droplets from membranes including the relationship between dynamic interfacial tension and the size of droplets [14][15][16][17], the lag time between consecutive droplets [18], and the number of active pores. In addition to the influence of the surfactant properties, these studies revealed that the dispersed phase flux also has an important influence as it determines the degree of surfactant depletion at the interface from surface expansion.…”