Membrane characterization using microscopic image analysis

Five organic ultrafiltration membranes, made of different materials (PES, PVDF and PAN), have been visualized by a field emission scanning electron microscope (FESEM). Obtained images have been treated by the processing and analysis program NIH image and parameters such as, porosity (Ak), pore density (N), mean pore radius (rp) and pore size distribution have been quantified for each membrane. The mean pore size obtained from image analysis agrees well with rejection data of fluorescein isothiocyanate dextrans, using the Ferry’s law approximation. The membrane thickness Δx has been also measured on images. Results allowed the comparison between the Ak/Δx values obtained from image analysis and the Ak/Δx values obtained by diffusion experiments. Results, combined with porosity and water permeability values, gave information on the material hydrophilicity.