Membrane characterization using microscopic image analysis

Five organic ultrafiltration membranes, made of different materials (PES, P VDF and PAN), have been visualized by a field emission scanning electron mi croscope (FESEM). Obtained images have been treated by the processing and a nalysis program NIH image and parameters such as, porosity (A(k)), pore den sity (N), mean pore radius (r(p)) and pore size distribution have been quan tified for each membrane. The mean pore size obtained from image analysis a grees well with rejection data of fluorescein isothiocyanate dextrans, usin g the Ferry's law approximation. The membrane thickness Deltax has been als o measured on images. Results allowed the comparison between the A(k)/Delta x values obtained from image analysis and the A(k)/Deltax values obtained b y diffusion experiments. Results, combined with porosity and water permeabi lity values, gave information on the material hydrophilicity. (C) 2001 Else vier Science B.V. All rights reserved.