Polymeric membrane is a proven technology for water purification and wastewater treatment. The membrane is also commercialized for gas separation, mainly for carbon dioxide removal and hydrogen recovery. Characterization techniques are excellent tools for exploring the membrane structure and the chemical properties. This information can be then optimized to improve the membrane for better performance. In this paper, characterization techniques for studying the physical structure such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) are discussed. Techniques for investigating the crystal structure such as X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), and wide-angle X-ray scattering (WAXS) are also considered. Other tools for determining the functional groups such Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and nuclear magnetic resonance (NMR) are reviewed. Methods for determining the elemental composition such as energy-dispersion X-ray spectroscopy (EDS), X-ray fluorescent (XRF), and X-ray photoelectron spectroscopy (XPS) are explored. The paper also gives general guidelines for sample preparation and data interpretation for each characterization technique.
Keywords: crystal structure; elemental composition; functional groups; gas-separation membrane; membrane characterization; surface analysis.