Liquid-liquid membrane dispersion in a stirred cell with and without controlled shear

Oil was passed through membranes into a continuous water phase containing a surfactant (Tween 20) to form oil dispersions with drop diameters between 40 and 400 mu m. Two types of stirred equipment were used: a Weissenberg rheometer (cone and plate geometry) providing constant shear stress at all radial positions which was modified to include a membrane instead of the plate and a simple stirred cell, with a paddle rotating above the membrane, providing variable shear with radial position. Experiments show that the simple paddle-stirred cell provided an oil drop dispersion that was as monosized as that produced by the controlled shear device, if not better. An analysis indicated that only the section of the membrane close to the radius of the highest shear under the paddle stirred membrane produced oil drops. The membranes used in the experiments contained a regular array of nontortuous pores uniformly spaced and provided oil injection rates up to 1000 L m(-2) h(-1), which is much higher than reported fluxes for the alternative tortuous pore channel membranes made by sintering.