Cut-off of dilute O/W emulsions through a microfiltration membrane

In order to obtain a monodispersed emulsion, we have used a cut-off process through a microfiltration membrane. Generally in the microfiltration process, a self-rejecting cake-layer formed at the initial stage of filtration would retain droplets, regardless of their size. It was therefore believed that separation based on relative size of pores and droplets through a microfiltration membrane was an impossible process. In the present study, it is assumed that removal of the self-rejecting cake-layer might enable cut-off to be realized through a microfiltration membrane. Based on this idea, both dead-end and cross-flow filtrations with stirred cell under conditions that avoid cake-layer formation were carried out. It is clear from the present experimental results that the cut-off process through microfiltration can be used to control droplet size under the special condition of no cake-layer formation, and the yield of this process can be predicted by values of the cut-off curve. A sieving mechanism should be the process responsible for the cut-off in the present experimental system.