Measurement of membrane pore interconnectivity

Several studies have suggested that the rate and extent of membrane fouling can be strongly affected by the interconnectivity of the membrane port: st ructure. For example, membranes with highly interconnected pores should all ow fluid to flow around and under any pore blockage on the membrane surface , significantly reducing the effect of this blockage on the filtrate flux. It has not, however, been possible to quantify these effects due to the abs ence of any experimental technique for measuring the pore connectivity. We have developed a new technique for evaluating the pore connectivity from da ta for the hydraulic permeability and/or solute diffusion coefficient in th e directions normal to and parallel to the membrane surface. Experiments we re performed by blocking different regions of the upper and lower surfaces of the membrane to change the relative contributions of the normal and tran sverse flows. Data were analyzed using a theoretical model for two-dimensio nal flow or transport in the porous membrane. Studies performed with polyvi nylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) membranes showe d distinct differences in the extent of pore connectivity, consistent with the different formation methods and underlying pore morphologies for these membranes. (C) 2000 Elsevier Science B.V. All rights reserved.