Determination of the Polymeric Membranes Pore Size Distribution by the Method of Capillary Flow Porometry

摘要

An accurate determination of membrane pore size and pore size distribution is important for media used in filtration and separation processes. Ultrafiltration membranes were produced from the solutions of various concentrations of polysulfone and polyoxadiazole (solvent N-methylpyrrolidone). Membrane films were produced from the polymer homogeneous solutions by the phase inversion method with the use of Automatic Coating Machine (Memcast™, Porometer NV). We varied the parameters, namely: cast thickness, casting speed, time of waiting. As a result, we produced the polymeric membranes of various thickness and porosity. Membrane pore sizes were determined with the use of the POROLUX™ 500 (Porometer NV), an instrument based on capillary flow porometry measuring pore size distribution and gas permeability. By means of the Porometer we measured the following properties of the membrane synthesized by us: the smallest, mean and bubble point pore sizes, air permeability, hydraulic flow, classification of pores according to sizes. For the samples where the POROLUX™ showed very small flow at the end pressure of 35 bar we used also the alternative method of Liquid Liquid Porometry (LLP). We researched the properties of the synthesized membrane such as trapping of the dispersed colloids and microorganisms containing in water and matching the optimal dimensions of the membrane pores. The obtained data is important for matching of the appropriate membrane for filtration process and for further research and modification of membranes.