Microchannel devices for the coalescence of dispersed droplets produced for use in rapid extraction processes

A new microchannel device has been proposed for the assisted coalescence of dispersed droplets produced by a micromixer for use in rapid extraction. The microchannel was of rectangular cross-section and easily fabricated by placing a thin aluminum foil frame from which the shape of the microchannel was cut out between two flat plates made of glass and/or PTFE. The depth of the microchannel was adjusted by the thickness of the foil. The proposed device has several advantages such as a flexible and easily adaptable design, easy maintenance, and cheap setup without the requirement of microfabrication. The coalescence of the dispersed droplets occurred by passing through the microchannel, to attain liquid-liquid separation. Various liquid-liquid dispersion systems were examined and the coalescence mechanism of the dispersed droplets was also considered. Within the microchannel, the dispersion droplets are distorted, the liquid-liquid interface destabilizes, and a velocity differential between the continuous and dispersed phases brought about. This proposed device will aid development of an efficient system for rapid liquid-liquid separation, which will allow extraction using a micromixing process to become a viable option in the near future. (C) 2004 Elsevier B.V. All rights reserved.