Swirl-flow membrane emulsification for high throughput of dispersed phase flux through shirasu porous glass (SPG) membrane

A novel technique using a swirl-flow was developed to obtain a high throughput of dispersed phase flux in membrane emulsification. Shirasu porous glass (SPG) was used as a microporous membrane, methyl laurate was used as dispersed oil phase, and sodium dodecyl sulfate (SDS) was used as an emulsifier.The SPG membrane was a tubular membrane with inner diameter, length, and pore size of 9x10^-3 m, 1.5x10^-1 m, and 5.2 μm, respectively. The continuous phase (water) was introduced into the inner space of the tubular membrane through an inlet tangential to the membrane axis to create swirl-flow. The swirl-flow velocity ranged from 0.85 to 5.4ms^-1, and the dispersed phase flux ranged from 0.3 to 3m³m^-2 h^-1. Size-controlled droplets devoid of satellite droplets were produced at specific swirling velocities, and the droplet size dispersal coefficient was between 0.45 and 0.64. The oil-phase-to-water-phase volume ratio reached a value of 0.4 after a single passage through the membrane module. The mean droplet diameter was about four times the membrane pore diameter, and was hardly influenced by the dispersed phase flux and the continuous phase swirling velocity. Swirl-flow membrane emulsification helped achieve extremely high throughput of the dispersed-phase flux and a stable emulsion was obtained.